EBME Forums
Posted By: leonius IEC leads control - 06/10/03 12:05 PM
How do all of you deal with the IEC 320 rolleyes leads being changed from machine to machine without knowlege of the EBME Dept.
The problem as i see it, as the leads are moved around the correct rated fuse in the lead is swapped. Also some leads are only two pin and therfore could get moved to a class 1 device. being a newbie this issue may aready have been discused in that case a link would be nice.
Posted By: Paul Balaam Re: IEC leads control - 06/10/03 12:42 PM
Big problem!!!!

Class II leads can't be stuck into class I sockets 'cos the earth pins in the way.

But as far as swapping the leads, thatís a different matter. I can't see any way around the problem, but what we do here is to put a laminated label around the lead indicating the lead was test on that particular machine on that date, if the staff swap the lead, then thatís up to them.

I have sent Memoís, spoken to the General Managers, emailed around the Trust not to swap leads, but still it happens. Iíve ended up sticking 3 amp fuses in all the leads apart from those that need a higher rating and if they are swapped and the fuse is popped, you can ask the question why was the lead changed?

Posted By: Allan H Re: IEC leads control - 06/10/03 1:10 PM
Big problem, no easy solution. I would indicate though that the fuse should not be a problem since the fuse is there to protect the cable and not the appliance, so rate the fuse to suit the cable.
Posted By: Anonymous Re: IEC leads control - 06/10/03 1:36 PM
0.75mm^2 up to 6A fused; 1.0mm^2 up to 10A fused; 1.5mm^2 up to 13A fused (for detachable IEC) isn't it? Depending upon the rating of the plug-top and IEC connector, of course. Any comments welcomed.
Posted By: grahamedriver Re: IEC leads control - 06/10/03 6:17 PM
Fuse is there to protect cable and provided it's right, it does.

Aren't detachable mains made detachable so they can be? Safely? What's the issue?
Posted By: Anonymous Re: IEC leads control - 06/10/03 7:17 PM
Don't think there is an issue as long as the fuse is rated correctly, the lead's inspected and safety-tested and identified as such.

Does anyone know of a reliable and effective method of managing the safety of IEC leads, including labelling as "inspected and tested"?

Any companies out there that produce a novel way of marking/labelling/identifying leads?

What inspection intervals should there be on IEC leads intended for use with medical equipment?
Posted By: Todd Mallow Re: IEC leads control - 06/10/03 7:31 PM

I have got to agree, the fuse is there to protect the cable. IEC leads are designed to be detachable so they can be used on different equipment. I have removed ALL 3 amp fuses from our cables as most are rated at 10A or more.
Why fit a 3A fuse to an IEC lead that is rated at 10A then plug it into a piece of equipment that draws 7A ?
3A fuses should not be fitted to IEC cables. I say 7A minimum.

Posted By: Roy Re: IEC leads control - 07/10/03 9:25 AM
We never use less than a 7 amp fuse. The heavier duty cables we fuse at 10 amps. Equipment which is rated lower than that is protected by its own fuses. In theory there should be no problem with swapping leads (except on high current equipment where it takes out the 7 amp fuse - but better that than melt the cable) but the detatchable leads are a real pain because they generate so many "false" failures - just because they're not plugged into the equipment properly.

There was a notice put out by the MDA a few years ago which suggested that all detatchable mains leads should be tested every six months because they were prone to damage. Ours get tested every 12 months along with all the toasters and kettles. The company who do the work stick a laminated label round the cable with the tested date on - but not a re-test date - just in case they're late getting round to it next year !

They find quite a few with the insulation pulled back or a connection broken - sometimes the earth - so it's definitely worth doing.
Posted By: BSM Re: IEC leads control - 07/10/03 10:01 AM
We check the IEC lead of the equipment with every PPM and apply a label indicating the ID no. of the equipment to which the lead is attached (at the time of testing), the date, fuse rating and engineers initials.

If any leads are found to be faulty or damaged, they are replaced.

This doesn't stop the users moving the leads between different pieces of equipment once we've gone, but without fitting retainers to fix the lead to the equipment, what can you do? confused
Posted By: Marcel Eve Re: IEC leads control - 07/10/03 4:26 PM
Some years ago I got fed up with the spare mains leads hidden in drawers problem. Staff would regularly "find" leads in drawers that hadn't been tested for years and stick them onto equipment.
I decided to serial number & log every IEC lead, following which I planned to forbid staff to use unlabelled "found" leads.

I chose a really robust cable labelling system and started testing & labelling. After about 500 leads (1/4 of the stock)I dropped the project.

It took 2 minutes to test a lead, 6 minutes to label it up!

6 years later I still find my labelled cables around, the numbering beatifully clear but quite impractical.

I used to fuse all syringe pumps at 1A until I started finding the leads swapped onto defibs. I standard fuse leads at 7A these days.
Posted By: grahamedriver Re: IEC leads control - 07/10/03 7:47 PM
It seems that several people have had the same idea. Fuse at 7A at least, sling any leads rated at less than 7A. That's what we do.

Al our leads are marked! A bit anal I know, but how else to know what's out there. Just recently w have seen quite a few dodgy leads - after years of them being OK - mainly fuses missing!

The things I hate most are leads with welded 13A ends - the plug top is welded or glued on to a hard plastic body and ones with hard plastic IEC ends which seem to want to drop out all the time
Posted By: Anonymous Re: IEC leads control - 07/10/03 7:58 PM
I find 13A fused IEC leads, usually moulded plugs marked with 13A on them with 6A or 10A rated cable and IEC connectors, occasionally. It appears that some people (not the EBME staff I work with) see 13A on a plug and assume that's the rating of the fuse that has to be fitted - some manufacturers as well. 10A fused and rated cables are suitable for the majority of equipment that I see.

Because IEC leads are removable and can end up anywhere the concern is really whether they're being checked, so I guess we're obliged to mark them up as inspected and tested. They probably present the highest risk of electric-shock to staff and patients if left unchecked for too long as Roy mentions - I suppose that's what all the fuss is about. Plus responsibility for checking leads can be established and maintained between EBME and Estates Electricians, using the appropriate labels, I suppose.

What's the consensus on which rewireable mains plug tops to use and the best moulded plugs/leads available? I did have a preference for MK hospital rewireables until they fitted those plastic rivets that break away, leaving the plug-top screw to support the mains pins when the plug's pushed into the wall socket. Still easier and quicker to wire than the MARBO plug tops we use where I work - I don't like the cable clamps that are screwed down or the standard slotted screw-connectors. I prefer the slotted strain-relief that the cable is pushed into and the threaded terminal-post connections.
Posted By: Alex Re: IEC leads control - 08/10/03 3:56 PM
We label the leads with the smae number as the equiment for example: 75234, all staff have been trained not to swop leads.

we refuse to accept or PPM equipment without the correct mains lead. They get reported to nurses forum, matrons forum, director of nursing, medical devices group. we ahve occasional missing of the leads. but the system does work.

Our Chief Executive has a personal interest in manangement of medical quipment and supports the department. I am accountable to him.

I also do regular ward round with the matrons and discuss issues with staff and point out non-conformities.

all seems to work very well.
get your chief executive involved and don't woffle to him, just give him the facts.
Posted By: VinceM Re: IEC leads control - 09/10/03 1:08 PM
Besides a visual check of the IEC leads and checking fuse and wiring connections. Is there any other test that I should be carrying out ?
Posted By: RoJo Re: IEC leads control - 09/10/03 1:21 PM
Earth continuity?
Posted By: Garrith Re: IEC leads control - 10/10/03 1:30 PM
Ok..I take the point that IEC leads are designed to be detachable, however, if the equipment no longer works because the fuse has blown in the mains lead - surely that indicates a problem with the equipment .... does it not?
Something has caused the fuse to blow ..it needs investigating not randomly swapping by a non-technical person.
As for fitting a 7 amp fuse in everything! - most manufacturers actually specify a fuse rating for the plugtop.
Posted By: Rog Rocks Re: IEC leads control - 10/10/03 1:39 PM
Does anyone know if there are any standards which dictate the maximum lenth of either a hard wired mains lead or one which is connected via an IEC socket for medical devices. If such standards do exist do you know what these standards are, and what maximum lengths they should be. I am aware that the Earth bonding test should yeild a result of less than 0.2 Ohms.
Posted By: Rog Rocks Re: IEC leads control - 10/10/03 1:41 PM
By the way, the maximum length for a tie should be 0M.
Posted By: John Sandham Re: IEC leads control - 10/10/03 3:49 PM
We have standardised on the 2M and 3M black IEC leads from RS for most equipment:
straight 2m 426-373 £4.77
straight 3m 262-1126 £5.64
Any problems with damage, loss or failing a safety inspection - bin it and put a new one on.
It means there is no need to open plugs to inspect the wiring and frees up valuable time for carrying out other maintenance.
All medical equipment is protected by in line fuses (Live and neutral) so it is acceptable to use a standard fuse rating on the leads. We normally use 3amp and 13amp fuses. Anything under 750Watts = 3A ; Over 750W = 13A. This means the majority is fused at 3A using a standard mains lead. As far as having longer leads, anything over 3Metres must be made up using orange (high visibility) cable to reduce hazards from trpping, or running over the cable with a trolley.

We have been known to tie wrap leads to equipment, especially from the equipment library to ensure they stay with the equipment. This works to a certain degree but the tie wrap self adhesive bases eventually come off, so not an ideal solution.
Posted By: Anonymous Re: IEC leads control - 10/10/03 5:53 PM
John, I know I'm being a bit picky and will be seen as argumentative but the RS IEC leads you listed are actually rated 10A (1.0mm^2). The attached plug may be 13A fuse rated but if you fuse to 13A then the fuse isn't rated correctly to protect the cable is it? Or is there actually a 13A moulded IEC cable available?
Posted By: John Sandham Re: IEC leads control - 10/10/03 6:59 PM
Well spotted. The leads from RS come with 13A fuses fitted as standard. In the majority of our leads we remove it and fit a 3A fuse. I believe that the IEC sockets are designed to operate at a max of 10A continuous (15A intermittent max), so if the medical equipment draws more than 10Amps continuous, it can't use an IEC socket.

The in line fuses protect the equipment, but the fuse in the 3 pin 13A plug protects the integrity of the supply in the event of a short circuit.
Posted By: Joe Emmerson Re: IEC leads control - 11/10/03 9:51 AM
John, I think you hit the nail on the head there.

In a detachable lead, the fuse is there to Protect the lead and it is up to the equipment manufacturer to provide suitable protection for the equipment by means of the equipment fitted fuse and appropiate rating.

IMHO, its a time consuming affair to mark the leads or to try and police the use of leads on differen equipment.

By reducing the fuse rating in the lead you are provided an extra safe zone for your users to reduce further the risks of the age old problem of lead swapping.

Admittedly the policies are all decided at local level by means of trial and error, what works for one person may not work for another. Provided we can stand our ground on the choice we make then that should suffice.

John, we pretty much adopted the same policy at Haslar, by changing the fuse to a reduced level and marking the lead and equipment with seperate tested / due stickers so that if the lead was to become detached it would still have some identification of its suitability for use.

Rog Rocks - provided the cable and plug is manufactured to 1363/a then I cant see any problem of using long leads. The longest i have come across in general use has been the 3m type provided by RS, however there may be some 5m versions available. I wouldent choose to make up a long lead, but would choose a pre-fabricated off the shelf one as you will be guarenteed that it will pass earth continuity tests at the required levels.
Posted By: Anonymous Re: IEC leads control - 11/10/03 10:16 AM
One of the very first things I was taught when I started in this game is that the mains fuse protects the mains cable, not the equipment. The medical standards state the requirements for equipment fusing. Hence the requirement to fuse at, or below, the continuous current rating of the cable. Well worth making clear to all of those techs never having done EST, possibly having to pick it up as they go along.

Yes John, I don't see 13A rated, moulded, IEC leads around. The cables and moulded IEC connector are rated IEC at 10A maximum, as far as I can tell. The 13A rewireable IEC connectors that you see on kettles are not recommended for Medical Equipment - wasn't there a purge to remove these, on MDA advice, a good few years ago? I don't think it good practice to manufacture 13A rated IEC leads for general use. Moulded leads seem to be a better idea, as you say yourself.

However there are general concerns about the quality of the strain relief on the IEC connector from all manufacturers (usually sheath pulls away from strain relief, exposing the seperate, insulated, conductors) or the connector disintergrates around the holes where the male IEC connector pins enter the moulded IEC. Some individuals also worry about the quality of the connections inside the moulded plugs, from experience of problems, so they remove the moulded plugs and replace with rewireable plug tops.

Rog: The length of IECs is limited by the earth-bond resistance limit in practice - of course this is dictated by the cross-sectional area of the earth-conductor isn't it? I think the earth-bond limit for the detachable IEC itself is effectively 0.1 Ohm if the earth-bond from the appliance IEC connector earth terminal to accessible earthed parts of the instrument approaches the 0.1 Ohm limit speciified in the general standards for medical equipement i.e. 0.2 Ohm overall, when connected to the instrument, checking it as part of the system. Since leads can move around then I guess if you allow 0.2 Ohm earth-bond for the IEC lead then there is a possibility of particular instrument/IEC lead combinations equipment failing the earth bond test. Does anybody have any views on this? I suppose, in this case, if it fails then replace it.

Perhaps Alex has the right idea when he says that the policy at the hospital where he works is to retain the IEC lead to the equipment. Incidentally; what are people doing about inspection, testing, rating and on-going maintenance of multi-socket extension blocks? Does anybody actually suggest the users purchase or use them? Is the use of them actually acceptable in these days or just a necessity? Do we turn a blind-eye to this practice or what?

A longer lead necessitates the use of 13A rated cable (to increase earth-conductor cross-sectional area, to reduce electrical resistance) and appropriately rated (mechanically and electrically) rewireable IEC connector. I think the use of excessively long leads should be frowned upon. Rewirable 13A IEC connectors are not particularly good connectors, electrically or mechanically, in my opinion. I say bring the power-source i.e. sockets, to the equipment. Long leads can give problems due to damage from being run-over, twisting leading to conductors being exposed through the outer sheath and the possibility of self-heating of the cable (at higher loads) when coiled incorrectly. Again; there have been warnings from the MDA, I think, about the inappropriate use of coiled extensions, long cables and suchlike.
Posted By: VinceM Re: IEC leads control - 13/10/03 9:27 AM
Is the writers from the tv series Casuality reading this ?
On saturdays show they couldn't use the defibulater because the lead was missing.

Spooky or what
Posted By: WOM Davis Re: IEC leads control - 13/10/03 9:51 AM
RL's Question:- what are people doing about inspection, testing, rating and on-going maintenance of multi-socket extension blocks? Does anybody actually suggest the users purchase or use them? Is the use of them actually acceptable in these days or just a necessity? Do we turn a blind-eye to this practice or what?

This is our Trust Bio-engineering group's view:-


1. Advice on use of MPSOs

The advice we give to Trust staff on the use of mains extension leads with medical equipment is based on BS EN 60601-1-1:2001. The main requirements of this standard are:
∑ The use of MPSOs should be avoided as far as possible – priority should be given to the installation of additional fixed socket outlets
∑ MPSOs shall not be placed on the floor and shall be mounted to prevent ingress of fluids and mechanical damage
∑ Connection to a MPSO shall only be possible by use of a tool, or the multiple portable socket outlet shall be supplied by an isolation transformer.

2. Testing of MPSOs

Clinical Physics/EBME has responsibility for testing all MPSOs fixed to medical equipment systems. It was agreed that testing procedures would be written into local work instructions. These should include the following:
1. MPSOs should be tested annually in addition to the electrical safety tests of each individual connected equipment.
2. Visual inspection of mains plug, flexible cable and MPSO. Identify signs of damage, overheating, fluid ingress etc. Internal inspection of mains plug and MPSO cord security, polarity, connections and contacts, unauthorised modifications or daisy-chaining, switches, plug fuse size appropriate to cable etc.
3. Polarity and continuity test of live and neutral on each socket outlet. This is easily performed on the Rigel 266 with the use of a standard IEC lead. Otherwise a standard ohmmeter will have to be used.
4. Earth continuity (bonding) test between earth pin on mains plug and each socket outlet earth terminal and other accessible metal parts. This should be tested at 10A and the resistance should be less than 0.1 ohm .
5. Insulation resistance between earth and both live and neutral pins of the mains plug. The test should be performed with all switches on. The resistance should normally be greater than 20 Mohm .
6. Total medical equipment system earth leakage. The current should be less than 0.5 mA with normal and reversed mains connection with all units live. Test not applicable if isolation transformer is fitted.
7. If an isolation transformer is fitted to the MPSO, the following additional tests should be performed.
a) Transformer earth leakage (less than 0.5 mA) and enclosure leakage (less than 0.1 mA).
b) Insulation resistance on the secondary side of transformer should be greater than 20 Mohm with all switches on (primary side insulation resistance only is tested by 5 above). This will require construction of a special lead with a mains socket at each end to connect the MPSO to the safety tester. This should be clearly marked “Test Purposes Only”, each plug should be fitted with a 3A fuse and have the live and neutral leads connected together as a safety precaution against misuse.

Posted By: Geoff Hannis Re: IEC leads control - 17/02/08 9:45 AM
This is an interesting topic, and discusses a problem that has not yet been finally (or, at least, universally) addressed and solved (as far as I'm aware). What's the present state of play, I wonder? Has anything changed? smile

OK, so we're agreed (?) that we "fuse to suit the cable". That's good, but which fuse do we use? 10 Amp?

Bill's post about multiple socket outlets on medical systems ("stacks" and the like, I presume) is also a good one. But what about trailing multiple socket outlets (Richard's point, I think)? In these days of "risk management", have we now all got rid of these? Especially from operating theatres and similar locations?

Note to Huw:- I feel another "EBME Best Biomed Practice" statement coming on - what news on the Wiki idea?
Posted By: Barney Re: IEC leads control - 17/02/08 1:30 PM
Well done Mr Geoff.

This is indeed an important yet unresolved issue in my department. Some time ago I wrote some findinds/observations on this topic and copied the information to the hospital's estates and EBME depatments. The estates department have taken action with their portable mains lead testing while my department languishes in doing nothing. Alas ignorance is bliss, but it will be interesting to see which department gets sued if a faulty lead electrocutes a patient.

As for the fuse rating of mains leads, when I did my electrical safety testing course, the then IEE recomendation was with either 3 or 13 ampere.

Posted By: Anonymous Re: IEC leads control - 17/02/08 2:04 PM
I think the latest medical electrical safety standard (BS EN 60601-1:2006) regarding medical systems states that 5mA earth leakage (NC) and 10mA earth leakage (SFC) are acceptable limits. The rationale states that the higher leakages do not present a significant risk above and beyond previous limits for earth leakage.

This encourages an increase in the number of connected devices, via MPSO, in my view but there is a lot more guidance and more explicit requirements when considering the use of an MPSO in the 3rd edition standard. Also the stuff published by NHS Estates and MHRA on appropriate use of trailing MPSOs, etc.

Acceptable limits for earth bond appear to have been pitched a bit higher for systems at a maximum of 0.4Ohm if MPSOs are used to interconnect devices producing medical systems. 62353 allows earth-bond up to 0.5Ohm as far as I'm aware - seems like acceptable earth bond limits are creeping-up slowly, generally speaking.

No doubt this current thinking on the use of MPSOs and relaxation of some EST limits is in line with the tendency for more devices to be interconnected as systems producing longer earth paths; plus acceptance of the fact that as long as additional earth bonding, non-conductive shielding, and mains separation, is used to limit patient leakages, under NC and SFC, then the other limits can be relaxed somewhat.

But we have to be careful - a few months ago I tested an endoscopy stack system where nearly every (well used) demo-stock IEC 606320 mains connector attached to each of the medical devices in the system exceeded 0.3Ohm (some >0.5-0.6Ohms).

It was the functional video connections (that can be removed/reconfigured anytime), in parallel with permanent, protective ones, that hid this fact until individual EST was performed on each device in the system (as it should). So beware.

Also, looking at MEIGN and references to group 2 locations, i.e. theatres using LIMS systems and suchlike, the recommendations from MHRA/IEE to install systems in the UK with 60601-1 compliant isolation/separating transformers - is apparently a means of imprvoving on safety aspects not necessarily covered the IEC standards for mains distribution in medical areas, perhaps.

The implication is that the connections of non-medical devices and MPSOs to medical devices are recognised in the latest manufacturing standards as is the requirement to improve the safety built into hospital distribution systems intended to connect to high risk areas.

This leads me to conclude that risks must be considered more acceptable as long as distribution & the medical systems that use MPSOs meet the requirements of the new 60601-1 standard, I suppose.

However this still means that selection and testing of appropriate MPSOs for use in medical systems becomes more important for those of us that must recommend their use in systems, re-configure existing systems or carry out acceptance tests and evaluations of medcial systems with MPSOs in them.

The fuse in the plug top protects the mains cable, the cross-sectional area of the mains cable determines the continuous current capacity of the conductors, the resistance of the earth conductor, which must be of the same or greater cross-sectional area, so this determines its maximum length.

It is possible to get 13A MPSOs with moulded plugs and appropriately rated cable but the concern is that if operators can access the sockets then it is possible to interconnect devices via the mains connections then this can compromise the safety of the medical electrical system.

For example under NC, if a combination of medical and non medical devices contributes to an earth leakage exceeding limits of 5mA, i.e. significant enclosure leakage currents over 10 times the acceptable enclosure leakage limit, and then the earth connection to the MPSO fails (SFC - Earth O/C) then patient and operator safety would be compromised.

This is why in addition to considerations relating to the MPSO inself consideration RE: non-conductive shielding, additional earthing or additional mains separation must be taken into account.

There are also more practical issues such as fluid ingress, higher risks relating to total loss of supply under fault conditions, robustness, fitness for purpose, etc, etc.

Fusing protects the mains lead fullstop. The mains BS 1362 fuse can continuously carry its rated value - hence the fuse rating should never exceed the mains cable, plug or IEC 60320 connector rating. 1A, 2A, 3A, 5A, 6A, 10A, 13A fuses are standard. Mains cables tend to be 10A rated, i.e. 1mm^2, on 10A rated IEC60320 connector terminated cables with 13A rated (and usually incorrectly fused at 13A, I might add) moulded plugs, up to a length of 3M.

Cable cross-sectional area of 0.75mm^2 - 6A rated, 1mm^2 - 10A rated, 1.25mm^2 - up to 13A rated. 2-pole fusing fitted to the Medical device looks after the device itself. So I say that 10A fuses probably give the most flexible use of detachable IEC leads rated at 10A (if you can ignore the fact that the time for a fuse to blow increases significantly when it passes a current in excess of its rating; as the value of the fuse increases).

The fuse in the mains plug should be rated at the lowest continuous rating of any component in the mains lead that is, obviously, also greater than the load current (usually a fuse of 1.5x non-inductive load current), i.e. maximum rating the same as Cable, Mains Plug, IEC Connector, or a lower maximum rating of fuse used, if a standard 1362 fuse does not exist at that limiting value (it should). The ratings are marked on all of the components if you look for them.
Posted By: Geoff Hannis Re: IEC leads control - 17/02/08 3:21 PM
Can we standardise on a 10 Amp fuse, then, do you reckon?

Meanwhile, did anyone miss Rojo's interesting suggestion about having different colour mains cables each year? smile
Posted By: Geoff Hannis Re: IEC leads control - 21/02/08 7:39 PM
During my daily wander around the wards this afternoon, I encountered no less than five bits of kit "plugged in" to a mains outlet, but not being charged, due to the dreaded IEC mains cable not being fully home in the socket at the back of the equipment (NIBP/SpO2 "monitors", as you've probably already guessed).

Back in the good old days of HTM-8 we had fixed mains cables, which had to be longer than a specified minimum length. When did the IEC cables come in, I wonder, and why? Is it because of the "pull away" capability? If this is (was) indeed the reason for their adoption, how come I see so many secured to equipment by cable ties, P-clips etc.? (not that either is much use in preventing the problem mentioned above, of course ... they simply keep the tested cable with its designated piece of kit.)

I suspect that we have been lumbered with these detachable mains cables simply because their use makes it easy for manufacturers to sell equipment worldwide, and just supply a cable with the appropriate (hopefully) mains plug at the other end.

Meanwhile, I've noticed some new powered beds with non-detachable mains cables. So what's going on here?

The trouble with the old non-detachable mains cables was that they were not always easy to replace (... that is putting it rather mildly in some cases emerging from the mists of my memory)!

... but back to IEC cables:-

Originally Posted By: KM
I wonder if anyone else hates these leads as much as me?

Seems that youíre not alone, Karl. Maybe we should start a campaign for a new standard. I suggest keeping the (now) ubiquitous IEC lead, but urging manufacturers to secure them by means of a retaining device needing tools to release (to change) the cable. The Graseby 500 volumetric infusion pump may be a good example. The WarmTouch bed warmer is another that comes to mind.

But, better yet, letís hope that the next round of equipment re-designs will see the IEC cable secured within the equipment, accessible by removal of a cover plate or some other such (neat) arrangement. smile
Posted By: Barney Re: IEC leads control - 21/02/08 8:47 PM
Well at least my old trusty Flymo lawn mover has a retaining clip over the IEC socket held by a spring that one has to open before fitting the IEC plug, it then acts as a clamp over the plug to prevent detachment. You could say a lot less bover with a hover.

Posted By: Geoff Hannis Re: IEC leads control - 21/02/08 8:57 PM
Yes, and some medical equipment manufacturers have tried these over the years, too. Unfortunately, they don't stop nursing staff (etc.) from yanking the cable free when they "need" it for something else. And, there have been cases where such clips have caused injury to "caring hands" during (for example) said yanking! smile
Posted By: Mike_d Re: IEC leads control - 22/02/08 8:19 AM
Are there specific clips available to prevent the pull away option on the mains leads? We have been asked in may areas to prevent this from happening as leads go missing and then there are not enough to charge equipment when required.
Posted By: Lee S Re: IEC leads control - 22/02/08 12:41 PM
I have seen P clips fitted to some equipment, it does not stop disconnection, but prevents the lead walking. Perhaps you could mount them using existing screw holes in the equipment (or would this constitute modification?) And would you need to carry out ďa risk assessmentĒ on whether the P clips hold on the cable could cause extra fatigue or would it increase the hazard risk when the equipment was wheeled away before being disconnected.

Maybe you should forget it.

Posted By: KM Re: IEC leads control - 22/02/08 3:04 PM
Blease / Spacelabs seem to have a good system on the back of there 8200s vents. Draeger use a similar one on the Anaesthetic machines.
Its a metal bracket that screws into the case and holds the IEC lead on.
Posted By: Geoff Hannis Re: IEC leads control - 22/02/08 8:08 PM
Some of you guys need to get real, I reckon. Only today, whilst carrying out a couple of "perfect PM's", I enhanced the equipment, and secured the mains cables (thereby preserving validity of the electrical safety tests carried out) by well-positioned P-clips. One used an existing screw position, whilst the other needed a hole to be drilled in an ECG recorder trolley. Hardly a modification, but just doing what the manufacturer should have done in the first place.

Meanwhile, if we must have "risk assessments", what about doing one on:-

Originally Posted By: Geoff Hannis
... I encountered no less than five bits of kit "plugged in" to a mains outlet, but not being charged, due to the dreaded IEC mains cable not being fully home in the socket at the back of the equipment ...

... and equipment failing when called into use in an emergency when the plug fuse blows due to the wrong IEC cable being grabbed from the stash of "spare mains leads", etc., etc.? smile

Originally Posted By: Lee S
... whether the P clips hold on the cable could cause extra fatigue or would it increase the hazard risk when the equipment was wheeled away before being disconnected.

What does cause unacceptable strain on mains cables is binding them onto rolling stands with cable ties!
Posted By: Lee S Re: IEC leads control - 24/02/08 5:35 PM
After you drilled the trolley did you put your new CE sticker on? after all having changed the original design of the trolley, as I understand it, you have taken on the manufacturers risk.

I have recently seen some quite good self adhesive P clips, however when one looks at the list of chemicals that can't be used to clean modern medical equipment I do wonder what the manufacturers would say.

An interesting alternate to the P clips and the cable ties I have seen is the tying of the mains cable around the equipment trolley.

Posted By: RoJo Re: IEC leads control - 25/02/08 9:18 AM
If someone trips over a mains lead and pulls out the IEC connector they can plug it in again. The machine will be out of action for a few seconds.
If this connector is restrained the mains lead may be broken. The machine may be out of action for minutes while a replacement is found and used, or hours/days if it needs a service person to repair it.
Easily removable plugs do have an advantage - they are easy to replace.
Or if it equipment is mounted on a pole stand it might be pulled over and broken. The detatchable IEC connector acts as a safety mechanism.
Do the benefits of a restrained mains lead - ease of safety testing - out weight the benefits of a easily fixable safety break?
Posted By: Lee S Re: IEC leads control - 25/02/08 10:16 AM
I don't believe that the manufacturers of medical equipment test their IEC sockets for insertion/detachment forces, having worked in destructive and non destructive testing before the NHS I could recommend some test equipment.

If the IEC connector is pulled straight out then it could prevent equipment being pulled over, however I am sure that many of you have repaired items that have been damaged when the IEC connector did not pull out. If my experience is anything to go by, you have also had to repair units where the IEC socket has pulled out of the equipment.

Retaining the mains lead would be more to do with the problems of having the correct size and type of mains lead with the equipment (and preferably the one that the equipment was tested with); as well as the incessant demand for replacement mains leads because staff have lost or removed leads (and the problems of do you retest as the mains lead is changed, who pays? Do you replace the batteries? Has the configuration been lost etc).

Posted By: John Sandham Re: IEC leads control - 25/02/08 2:58 PM
I think that a simple locking clamp could solve the problem of loose IEC leads. A very annoying (and common) occurrence. Why don't more manufacturers use this simple solution? smile I go with your 10A fuse solution Geoff. All medical equipment is already double fused at the IEC input.
Posted By: Geoff Hannis Re: IEC leads control - 25/02/08 9:41 PM
Originally Posted By: John Sandham
Why don't more manufacturers use this simple solution?

Simple, John ... because no-one forces them to! If manufacturers are the only ones "allowed" to "modify" equipment, then somehow this issue has to be raised with them.

I've often wondered if any of the manufacturers ever take a look at what goes on at this forum (any one reading this?). But somehow I doubt it. But if they do, let's hope we hear from them soon. smile
Posted By: John Sandham Re: IEC leads control - 25/02/08 9:55 PM
Geoff, I can assure you that they do take notice of this forum. They understand the importance of having the EBME community on their side.

I speak to our website sponsors on a regular basis, and although they do not often post, they do keep a close eye on our comments. smile I think that some messages get through and changes are made, but maybe not as fast as we would like.
Posted By: Geoff Hannis Re: IEC leads control - 26/02/08 6:22 AM
Well thatís good news, then, John. Seeing that we all seem agreed (more or less) that the issues revolving around IEC mains cables need to be addressed, Iím sure weíll all be looking forward to some elegant resolutions from the manufacturers soon! smile
Posted By: Paul Horn Re: IEC leads control - 22/07/08 10:48 AM
This is the best solution that I have come across from the perspective of simplicity and reliability;


It is even quite effective against the 'determined' nurse!
Posted By: Geoff Hannis Re: IEC leads control - 22/07/08 11:01 AM
Interesting, Paul. Defeats the much-trumpeted break-away "feature" of the standard IEC connection though, doesn't it (not that I'm a great fan of that)! Notice that they fit a 5 A fuse (we would prefer 10 A, would we not). But could these indeed be "the answer"? And the price looks OK. Has anyone tried them yet? smile
Posted By: Paul Horn Re: IEC leads control - 28/07/08 9:59 AM
We only have a couple in use (and these are on devices with the IEC inlet on the underside of equipment, and therefore vulnerable to gravity when moved about). Not really an objective assessment of suitability in the areas that cause us the most problems - though it is nonetheless a very neat solution.
What is really needed is a 'field trial' on some mobile equipment library equipment, but we hav'nt got this justified yet
Posted By: Geoff Hannis Re: IEC leads control - 28/07/08 10:04 AM
Sounds like a useful topic for discussion at the infamous "Blackpool Forum" to me, then, Paul! smile
Posted By: bcarlisle Re: IEC leads control - 28/07/08 11:05 AM
How about just making all the cables the same with the same fuse and everything. You can then label them all up and dump them in a box just inside their equipment cupboards.

Because thats what they have always done and always will unless they are locked on to the equipment like the Graseby 500's and even they were sometimes removed by the sprint fom the bed with it still plugged in.

Posted By: Geoff Hannis Re: IEC leads control - 28/07/08 11:27 AM
Hey, Billy ... you've really "got one on ye" this morning, Mate!

Anyway, we've had the discussion about fuse ratings before, and the Elders decided that 10 A for all standard IEC leads was the way to go (haven't you been paying attention, either?).

Also, if you don't like the idea of nurses squirreling away "spare" cables, why not simply take them away when you find them? Of (if you prefer), just cut the plugs off? smile
Posted By: Geoff Hannis Re: IEC leads control - 20/05/14 4:51 PM

Has anyone tried this one? think
Posted By: Geoff Hannis Re: IEC leads control - 19/09/14 7:08 AM

I'll take that as a "No", then. frown
Posted By: Geoff Hannis Re: IEC leads control - 02/01/17 9:14 PM

Originally Posted By: Geoff Hannis

Has anyone tried this one? think

I see that MCC are doing them now.

Has anyone tried them? Are they any good? Do they solve the "problem"? think

See also - retaining clips!
Posted By: Malcolm Re: IEC leads control - 03/01/17 7:58 AM
At least one positive side to living on the continent......

NO f*į+ing fuses in plug tops!!!!!!

Posted By: Geoff Hannis Re: IEC leads control - 03/01/17 12:40 PM

Not good, Malcolm ... unprotected mains cables! tut
Posted By: DaveC in Oz Re: IEC leads control - 04/01/17 1:06 AM
Same here in Oz. Took me quite a while to get used to the idea of not having a fuse in the plug but I don't even think about it now.
Plenty of other protection about.
Posted By: Geoff Hannis Re: IEC leads control - 04/01/17 12:13 PM

Also a 50/50 chance every time of reversed "live" and "neutral". frown

Probably OK with "new" kit, and distribution systems which have circuit breakers in every line (and every outlet individually protected) ... but otherwise, there must be [are] places out in the Bush (and corresponding locations in other parts of the world) where the Good Old British approach would be a safer bet! smile

As an aside, I can remember many years ago (when the majority of kit still had a fixed mains cable) we used to fit plug fuses according to the equipment themselves - many of which would have been otherwise unfused. The idea being that every SAM suction pump (etc.) had a 7-Amp fuse (or whatever). That was probably about the time I started making lists!

And yes, I still fit the "correct" plug fuse on my own kit (soldering irons, chargers, computers, and so forth). I also like RCD's in the workshop (kitchen these days), as well! Some habits are worth preserving if you hope to survive.
Posted By: Geoff Hannis Re: IEC leads control - 04/01/17 7:24 PM

I have since remembered that the typical (and distinctive) Australian power plug is in fact polarized ... so the "mains reversal" situation (which I believe is actually a Single Fault Condition - SFC) should not occur.

That may not be true in Malcolm's situation, however ... depending upon which variety of Ticino plug he is used to seeing; although I know that plug and sockets arrangements can (and do) vary across "harmonized" Europe.

That's the nice thing about Standards; there are so many to choose from. whistle

See here for reference.

I may as well mention (yet again) the infamous "Hospital Grade" ("Green Dot") plug as found in the USA. Also non-fused, of course, despite mains cables carrying heavier current (at only 110 volts).

Although following the same configuration as normal (lesser, cheaper) plugs, these (expensive) plugs are intended to mate in similar sockets, with special requirements regarding "tension" (as in, resistance to being yanked out). All well and good, except that (unless it has changed in recent times) the basic design has the (heavy) cable sticking out from the wall (rather that hanging down gracefully as our BS-1363 does), leading to the usual "sagging" so often seen (with the heavy "washing line" doing the best it can to tip the plug out of secure attachment in the socket).

All that's needed there (I would suggest) is a re-design to have the cable hanging down at 90 degrees. Indeed, I seem to recall having seen a couple of US-style plugs that did exactly that (although I can't remember if they were in fact Hospital Grade).

The other "problem" I have with Hospital Grade is that they are (I believe) only mandated in "Critical Care" areas. So what about all the medical kit used outside those areas? And what about plugging Hospital Grade into "normal" outlets, and vice-versa ... I'll leave it there (for now, at least). smile

For more, see here.
Posted By: Geoff Hannis Re: IEC leads control - 05/01/17 5:07 PM

OK ... back to the topic; especially with regard to the original discussion about what has become the entrenched practice of users swapping (grabbing) detachable mains cables as as when needed, leaving them dangling (and engerized) from bedhead units ... and all the rest - and what our response should be. Perhaps the time has come to summarize the thread, and (who knows) seek out the latest opinions!

Specifically, I'm refering here to the ubiquitous detachable "IEC cables" that are found in hospitals these days in great number. In the UK these will be BS-1363 (most likely the sturdier BS-1363/A variety) fused plus with a three core cable rated at 10-Amps coupled to an IEC-60320 connector in C13 configuration. In other parts of the world the plug will be whichever one is used (and probably not fused); but the cable and IEC connector are likely to be the same as those mentioned.

A smaller number of other possibilities are bound to exist as well; BS-1363 to IEC C5, for example (as found connected to laptop chargers, and what-have-you), but for sake of argument let's stick with IEC C13 here.

In short, I believe we need to accept the situation as it is, then try to manage "our side of things" (electrical safety, mainly) as best we can. We need to accept that although we may have tested out a system only yesterday, its integrity may very well have already been brought into doubt (after a nurse has snatched up the mains cable for some other urgent task).

My suggestion is basically that all mains cables are equal!

What I mean is, as long as they they are not damaged, or proven to be faulty, then any one cable should be as good as the rest, or any other.

How do we get to this happy state of affairs? How about:-

1) Deciding upon (sourcing) a cable of sufficient quality that we biomeds will be happy with it! Then endeavouring to standarize on that one throughout.

2) Specify (and/or fit) a 10-Amp BS-1362 fuse (that is, a black one) in every plug top.

3) Don't be too fussy if equipment comes into the workshop without a cable. Similarly, don't worry about them being missing when kit is returned to the Equipment Library. But always issue a new cable to accompany the kit as it leaves the workshop or Library.

4) By all means check the complete equipment (that is, complete with cable - how else could you do it?) during PM and after repairs ... but more than that, be obsessive about checking every cable you come across as you stride around your domain.

5) ... and (whilst striding) carry a bag of new cables when out on your rounds so as to be able to swap any dodgy looking cable(s) encountered - then bring those back, cut off both ends, and discard them (the cables themselves may have some scrap value - and the fuses can be removed and used again). If you are feeling really macho you could always carry your side-cutters with you and so be able to impress anyone looking on by neutering those junk cables right there at the Nurses' Station!

6) Be assertive also when digging into the famous cupboards and "spare cables" drawers out on the wards. Drag out all the cables (as well as the rats' nests of old ECG lead wires, "mains adaptors" and all the rest) and bin them all! But be sure to leave a couple of your nice new cables with the Head Nurse before making good your escape.

By following such an approach as outlined above - and continuing to carry it through - you should ultimately end up with a hospital full of decent mains cables that you may be proud of (and confident in)!

In many ways good in-house tech support is a bit like husbandry. Anyone who has had anything to do with farming must have noticed the farmer wandering around, prodding here and there with his stick, and generally "making good" (mending fences, or whatever) as he went along; and not holding back when the time comes to cull (and thereby, improve) the herd! smile
Posted By: Geoff Hannis Re: IEC leads control - 05/01/17 5:24 PM

In theory, it would be Good Practice to have a system in place that sees mains cables regularly (define "regularly"!) examined for condition, and tested for electrical safety and integrity (insulation, continuity).

However (and as we have seen), this only makes sense if such tests can be documented, which also means that the cables need to be readily indentifiable. That way results can be recorded on our favourite database, spreadsheet, log-book etc.

But how to do this? And how to do it without spending (wasting) endless man-hours that most likely would have been more gainfully expended elsewhere?

We have seen mention of:-

1) Colour-coded cables
2) Individual labelling

I have given this aspect (labelling, recording) a fair amount of thought, and have yet to come up with anything definitive; other than, if you have the resources to tag and record, then by all means do it - but (on the other hand) if you don't, then concentrate instead on the "quality assurance" measures
outlined in the above post.

And, if pressed by Senior Management or Quality Audit Inspectors (or whomever), simply issue a blanket statement along the lines of "a rolling programme of examination and testing of all detachable mains cables is in place"! smile
Posted By: Geoff Hannis Re: IEC leads control - 08/04/21 2:30 PM
Originally Posted by DaveC in Oz
Don't know what the rules are in the UK and elsewhere but down this way (Aus/NZ) detachable mains cables need their own label which specifies not only test/next test date but the asset number of the device with which the cable was tested, that way you know where the test results are for earth resistance etc should the cable be moved to a different device, as often happens, and that device were to be involved in an incident.

Fixed mains cables do not require a separate label but we often do anyway out of habit as much as anything.
Sounds sensible to me (apart from the un-fused plugs, of course).

Does AS/NZ 3551 call for this?

Is this (labeling of mains cables) common practice anywhere else in the world, I wonder?

On the other hand (see post #21330):-

Originally Posted by Marcel Eve
It took 2 minutes to test a lead, 6 minutes to label it up!
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