EBME Forums Forums Maintenance Technical Assistance Micro-Shock data

Geoff, you may be interested to note that as part of the two day version of my course at PTT in Tring, on 4/5 April we have built a board which represents a Medical Location. The idea being is to teach the radial equipotential bonding system and how Medical IT and TN-S socket outlets are earthed.

https://www.proactivetechnicaltraining.co.uk/specialist-training/medical-electrical-installations.

I found your comments about the wall between Estates and Medical Engineers interesting. It is a defined regulatory boundary but my course "lowers" the wall and moves it slightly with a new step-over dwarf wall into the Medical IT socket-outlets section and the Medical Location equipotential bonding system. This is so medical engineers UNDERSTAND it - not work on it. In fact HTM 06-01 does actually suggest clinical staff are trained on alarms - nigh on impossible with agency nurses so teaching medical engineers about these aspects will certainly help when they participate in the Electrical Safety Group for example.

Yes; it's nice to have training bay "mock-ups"; many training establishments use them.

About "demarcation":- my view (and one I have held for many years) is that all engineering services in the hospital should come under a Technical Services Director - who should, of course, be a Clinical Engineer.

And technicians should be "multi-skilled" (especially from the "electrical" point of view). Surely I am not the only one who has ventured into hospital plant rooms when the need arose?

From personal experience, I have been in situations (overseas) where I myself - as the Chief Biomed - was very much at the Top Table of the hospital management; as well as standing-in as Project Manager when the regular guy was away. I was by no means exceptional; but this was just the way that the biomed was respected* in those places.

Sadly, I have found things to be much different in the UK, with many folk intent on protecting their turf (and building their empires) at all costs (including failing to support the medical staff, and, on some occasions, the patients).

Let's move that wall!

* And "respect" - or rather, lack of it - is something that has been moaned about a fair bit on this forum over the years.

LIMs? ... Fire alarms? Nurse calls? ...

Who else are they supposed to be for?

Sorry - Medical IT alarms. They give a lamp indication with the first transient fault instead of disconnecting the supply like an RCD.

What was wrong with the LIM? It gave an audible alarm above a defined amount of (predictive) leakage current, but better than that (in my opinion) you could watch the meter as equipment was plugged in (and unplugged).

Too much "dumbing down", again in my opinion.

What’s a LIM Geoff?

Line Isolation Monitor ... a term used in many parts of the world (especially those that follow NFPA-99). LIMs were (are) only found in IPS (Medical IT) locations, such as Operating Theatres.

Although modern ones display "Total Hazard Current" digitally, the earlier ones used an analogue meter ... where (as I say) you - the biomed tech - could watch the meter and pretty quickly establish which piece of kit was causing the problem (as well as its magnitude); it's difficult to do that if all that is displayed are a couple of indicator lamps.

See the "before" and "after" in this link.

The documents discussed in this thread (HTM 06-01, GN7) mention an Insulation Monitoring Device (IMD) but I understand that this is something else. As in insulation -versus- isolation; and that they display kilohms (when visible) -versus- mA. Personally, I prefer the LIM (biomeds tend to think in leakage currents, rather than line impedances, or whatever).

You might find this old thread of interest, Ian. Also this one (both of which you may wish to add to).

Thank you. I remember them now. I see Mike eventually came in and corrected the thread to say that Medical IT is only to maintain the supply with the first transient fault because Residual Current Devices would disconnect even with a transient fault. Period.

Manufacturers certainly got on the bandwagon - I even saw an MRI suite recently with Medical IT. They couldn't answer my simple question as to why - I found out that the designers had made this decision off their own back.

Was this before or after Electrical Safety Groups appeared on the scene?

Actually, I would be interested in learning more about that one:- Where? Who were the Consulting Engineers/Designers? Not to mention, how much extra did it cost? Answer by PM only, though, Ian.

After HTM but still no ESG. I think I'm going to start offering myself as an ESG promo consultant.