Group 1 Medical location - maximum resistance between EBB, socket outlet and exposed conductive part - part 2 of 2

There is an excellent article available on the internet written by Ian Chell MSc FSRP a Birmingham City University visiting lecturer, who is working with Viji on the Medical Device module at the university.

medical-locations.co.uk

This article was published on the 30th September 2019, after the requirements for Medical Locations were revised and updated in the current edition of BS7671 The Wiring Regulations.

medical-locations.co.uk/.../Pocket-Guide-for-Medical-Electrical-Installations-30-Sept-2019.pdf

There is an excellent article available on the internet written by Ian Chell MSc FSRP a Birmingham City University visiting lecturer, who is working with Viji on the Medical Device module at the university.

medical-locations.co.uk

This article was published on the 30th September 2019, after the requirements for Medical Locations were revised and updated in the current edition of BS7671 The Wiring Regulations.

medical-locations.co.uk/.../Pocket-Guide-for-Medical-Electrical-Installations-30-Sept-2019.pdf

That is an interesting document, but I am a little surprised to see  the insistence of all sockets being on the same phase.
I'm also surprised by the recommendation to use 4mm to 'banana plug' adaptors and  wander lead to verify this - testing an in service installation this means the wander lead is connected to the reference phase. Now  the short lead in the testers hand is current limited via the meter - which is probably a high impedance unit, reducing any potential for shock with contact with the exposed banana.  I appreciate the test leads are shrouded bananas, but in a working ward or similar I'd have thought a long live single inuslated  wander lead is some way from ideal.
Any what is the risk to patient of having 2 phases present anyway ? One phase to earth is the far more common failure mode.

Mike.

An interesting read. I spotted the "Medical IT socket-outlets" (not something I was aware of) and did a search to better understand what there were.

One point that came out was the recommendation(?) that they should be unswitched and then a discussion about medical-it-socket-outlets and who's choice it was, plus that the switched sockets er easily available on line e.g. selectric-smooth-13-amp-blue-medical-socket-outlets (google's 1st listed)

Definitely some interesting considerations.

mapj1 said:

recommendation to use 4mm to 'banana plug' adaptors

I'm guessing they don't want the medical sockets opened as part of testing with possible disturbance to the connections.

mapj1 said:

One phase to earth is the far more common failure mode.

But it's always the 'Neutral' phase in an insulated IT system, because it's not a faulty fault until the second fault.   The first fault makes it 'PME' in some senses, and then that other phase becomes a hassle.

I could be completely wrong though...