Hi all
I'm wondering what precautions people take when working on 'live' equipment. I've been presented with a draft document that says anyone working on equipment where it is possible to touch live (> 50V ac)must use an isolation transformer and cannot work alone.

There seems to be no mention of personel having been trained (BTEC's/degrees/manufacturers)or having our workshop ccts on RCD's etc.

Any thoughts appreciated.

My dearest Gareth, there is an awful deal of foundationless self installed paranoia dealt upon our fellow functionals up and down this great nation of ours. The basic fact, and I beg anyone who knows otherwise, is we our governed by The Electricity at Work Regulations 1989, this is a plain and simple truth, so I invite all you parnoid masters out their to get thy facts together before you bark. The regulations clearly contain the following:-\

Work on or near live conductors

14. No person shall be engaged in any work activity on or so near any live conductor (other than one suitably covered with insulating material so as to prevent danger) that danger may arise unless-
(a) it is unreasonable in all the circumstances for it to be dead; and
(b) it is reasonable in all the circumstances for him to be at work on or near it while it is live; and
(c) suitable precautions (including where necessary the provision of suitable protective equipment) are taken to prevent injury. (i.e. RCD's etc)

Persons to be competent to prevent danger and injury

16. No person shall be engaged in any work activity where technical knowledge or experience is necessary to prevent danger or, where appropriate, injury, unless he possesses such knowledge or experience, or is under such degree of supervision as may be appropriate having regard to the nature of the work. (our qualifications)

There are many other items of interest, you may find this grand offering on the following link:-

web page

Kind regards all

We have recently looked at safety for working on live equipment. The problem is to find 'suitable precautions' as required by the regulations.
RCD's do not mix well with the filter circuits in IT equipment, so a separate circuit may be necessary for the workshop pc's. A full ring circuit RDC will probably trip at 30mA, which is rather high for personal safety.

My inclination is to use an isolation transformer when working on live portable equipment.

Warning notices, locked doors, permit-to-work, second person - all should be considered but may not be suitable or required in view of the risks.

Mark

RCD's will save your life if your careless or unlucky, but they won't prevent injury - the shock will still make you jump !
Some guidance I read recently suggested that rather than use the equipment power supply with un-protected mains terminals etc it is safer to use external low voltage supplies to power the equipment. This could be very time consuming to set up, may require quite a few supplies and could cause major damage if the supplies are switched on in the "wrong" sequence !

It's back to the old risk assessment routine ! If people are trained and qualified and know the danger in working with live equipment - and have been given the correct tools and adequate test equipment - then they can reasonably be expected to be responsible for their own safety. If we all have to spend our working day holding one anothers hand and watching to see that nobody gets electrocuted, we won't get a lot done.

When was the last time anyone heard of a Tech getting electrocuted ? The last one I know of (he was burnt, not killed) was over 20 years ago !

The main danger with working on live equipment is that someone else who doesn't understand what your doing and is being nosey comes sniffing round and pokes at something they shouldn't, so warning notices are the best protection - and being careful about the location if you have to work out of the department.

You may wish to consult BS EN50191:2001 "Erection and operation of electrical test equipment". It may be relevant.

On this one, which like most of us, has tended to dominate my life.

Has anyone looked at HTM 2020 or recommendations from RETRA?

No matter what any of us say, if one of us is electrocuted, we would not have a leg to stand on in terms of the HSE. They take the guidance as it is.

Get electrocuted and we clearly did not follow the guidance, eg 'dead', ' insulated', see you in court afterwards.

RCD down to 10mA, isolation transformer(s), EARTH FREE ZONE, cordoned off, isolation trips around the department, etc, etc.

We haven't done the above, told to do so or accept the consequences when someone suffers.

Watch this space, in time that is.

In light of the recent Safety Action Notice released by Scottish Healthcare Supplies on "Live Working". What measures do you have in place at present? Are they adequate? Are they to the specification indicated in the bulletin or do they exceed it? If not are we all doing something different? I have looked at the MHRA website but this bulletin does not appear to have been released in England. Are the Scots the only ones being hit with this one?

Looks to me like Louis got it right back in September 2002 !! In my humble, but probably reasonably typical experience, by far the greatest “real world” danger has been idiot “colleagues” twiddling away somewhere out of view whilst I was poking about elsewhere in the (x-ray) system! It may be against somebody’s “rules” (seems that most things I do are, these days), but personally I would much rather work alone (…only got myself to blame then). Clear the room of all distractions (eg, “staff”), (locking the door if necessary to keep the blighters out) and proceed slowly and cautiously, preferable with brain engaged. And of course, when working on live HV, keep one hand firmly planted in pocket!

For the record, a very long time ago now I was thrown across a radar van after encountering EHT at the back of a radar display, but that was my own dumb fault (that sort of thing teaches “respect” – if you survive, that is!). HV means High Voltage (believe it or not), and x-ray systems can’t help but generate lots of it. It can easily kill you if you’re not very careful – “pump boys” beware!

I was once also rather frightened by HV flashing down a ceiling-hung HT cable under which I happened to be standing (but we had to put out the room lights to discover that one). A bit shaky afterwards, I’ll admit, but sometimes you just have to hope that the Gods of Biomed are smiling down on you!

Come on guys, any more tales like this? Be honest, now …

Don,t forget to test for Live Chassis as well as hand in pocket Geoff. I remember that cable in the Royal Hashemite Kingdom of Jordan !!!the old Medina Hospital was,nt it ?? and also the look of horror on Dave Martin,s face
( Siemens Engineer ) I think we concluded, we,d better change the cable then !! Oh Happy Days.

Well, Tony, seeing that you’ve “named names”, I’d better not deny or confirm! Let’s just say that your memory must be sharper than mine!

But would I be right in assuming that the test for live chassis is a hang-over from your TV days?

Touché?