EBME Forums Forums Management Medical Equipment Management Equipotential connections usage - Poll

Currently BS 7671 specifies the quantity of equipotential connection points required for medical locations. There are proposals to change this in the next version to allow the designer, in conjunction with the medical staff, to decide on the quantity and even if to supply them at all in some areas.

Are the connection points actually used to connect medical equipment, via the equipotential bonding connector sometimes found on medical equipment, to the supplied connection point of the electrical installation?

Do you use equipotential connection leads with medical equipment single choice
	Yes, we use them all the time.
	Yes, we use them but only occasionally.
	No, we never use them
	What the heck are these connections!
Votes accepted starting: 30/08/17 8:56 AM
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If someone votes they use them occasionally could they post why they have used them and for what type of equipment.

"They" (the cardiographer) thought that using* them might reduce the "interference" on the electrocardiogram. It didn't.

But what did improve the trace was my explanation that, nine times out of ten, such problems were (are) due to "poor" contact at the patient electrodes.

Bottom line? IMHO Equipotential Points are (yet another) Red Herring (at best); and waste of time and money (at worst).

As an aside, I have also seen them put to good use in providing a de-facto "earth" for equipment such as CTG, ECG, EEG and similar where, for whatever reason (the "wrong" mains cable and [or] plug being the usual one), no integral protective conductor was in place. But, I hasten to add, such instances have been "outside of the UK"!

* Stringing a green/yellow coloured cable between the stud on the ECG Recorder to the stud on the wall.

Although nothing to do with providing them within a medical location (aka room) - they* often come in handy when trying to find an "earth" point for carrying out electrical safety tests. Allegedly.

* The Equipotential Stud on the back of some machines.

Geoff totally agree with you

Also very handy in Italy for removing the ever present static charge.

On what equipment?

Class I medical electrical equipment should have a functioning earth connection anyway. Class II devices are rarely fitted with a connection point. Patient beds and other such equipment will have anti-static wheels (or other similar measures), as they are intended to be moved.

As most static is generated by people with incorrect (not anti-static) clothing, floors that are not anti-static or the humidity is too low. I have seen it in many rooms where the cleaner uses the wrong polish and creates a high resistance barrier leading to build up of static. This build up can play havoc with ECG traces never mind static shocks. No amount of equipotential bonding connections will help here!

I should also point out that these connections they were never intended to reduce static!

Malcolm, get rid of that Bticino stuff ... and get some proper plugs and sockets in there (eg, BS-1363).

Meanwhile, here are a couple of nice (but oldish) .pdf's that may help in understanding the issues involved:-

1) electrical.theiet.org/wiring-matters/38/medical-locations.cfm?type=pdf
2) electrical.theiet.org/wiring-regulations/updates/gn7-2015-errata.cfm?type=pdf

To "cut to the chase", Equipotential Bonding is really about earthing the water taps, gas pipes and so forth!

In other words, it is really to do with the building, rather than the portable medical equipment per se.

Good evening. If it helps, supplementary bonding conductors are meant to act as a back up to the medical device's earth conductor in the mains flex. It serves no other purpose. The connection points you refer to I guess are the supplementary bonding connectors referred to in 9.12 in GN7? The wall connectors should not be used to measure the earth resistance in a medical location. The reference point to be used is the Equipotential Bonding Busbar in the medical location. However, the SBC can at least be used for quick checks.


Regards

Ian

Welcome to the forum, Ian.

This brochure makes interesting reading.

Note the stated requirements of (the present edition of) BS-7671.

My own "doubts" about the value of Supplementary Equipotential Bonding plugs and sockets in medical locations is that they are just something else for medical staff to worry about (misunderstand, whatever). And they have, by the way, been about in some hospitals for many years ... so I can attest to the "confusion" clause!

I also believe there may also sometimes be a level of confusion regarding the usefulness (or otherwise) of SEB (SBC, whatever) in medical rooms, and the related Equipotential "studs" often found on the back of portable and (or) mobile medical equipment.

This last category (the studs) may have some value in certain situations (cath lab, major surgery etc.) where "daisy chaining" together the studs of many items of equipment to ensure that all equipment chassis sit at the same zero volts may be beneficial for various reasons (the main one being, of course, the electrical safety of the patient).

Meanwhile, I continue to uphold the view that the primary "safety feature" of Class I medical equipment is the protective ("earth") conductor in its mains power cable - and that safety (and a whole load of other Good Things) is ensured by a continuous programme of properly conducted preventive maintenance - by the biomeds. In fact it has always be thus! That's where the money needs to be spent; not on ever increasing layers of "smart" technology.