Supplementary equipotential earth bonding points for Group 1 medical locations

Simon Bourke said:

there are no invasive procedures.

 - the equipment being used is a blood pressure monitor, (type BF as defined in BS EN 6061)

Clarification is required here. I cannot find BS EN 6061, but BS EN IEC 60601-2-34 refers to, "invasive blood pressure monitoring equipment" (my emphasis). Part 2-30 refers to, "non-invasive sphygmomanometers", but I can see no mention of, "type BF".

ETA: I have now found a reference to, "applied parts" and, "type BF" in BS EN 80601-1 and of course, there is the definition of, "applied part" on page 37 of BS 7671:2018+A2:2022.

So what sort of blood pressure monitor are you referring to?

The regulation is this one

The reference is here

The equipment is as below

Simon Bourke said:

BS7671 clause 710.415.2.1 requires that in each medical location of Group 1  activity, supplementary equipotential bonding connection points shall be installed.

It states: Supplementary equipotential bonding connection points for the connection of ME equipment shall be provided in each medical location, as follows: Group 1: a minimum of one per patient location.

Who classified this as a Group 1 location? For example, 'examination or treatment room' is listed in Table A710, but that is a "list of examples' and the text of A710 says 'Regulation 710.3 cannot be satisfied by using this table alone'.

Specifically, Regulation 710.3 says that medical staff should provide an input, so to assist in classifying the locations ... there are further details in the HTMs as to how the classification is assigned.

Simon Bourke said:

Is a deviation from the regulation permitted as long as the reason is stated on the test certificate?

BS 7671 permits 'intended departures' (Regulation 120.3) but :

(a) given Regulation 710.3, is this a decision for the electrical installation designer alone? and

(b) Regulation 120.3 requires that 'The resulting degree of safety of the installation shall be not less than that obtained by compliance with the Regulations.'

Simon, I fear that AI has been unhelpful again, but the various standards could be clearer.

Your description in the OP seems to be a perfectly ordinary consulting room (what the Americans call an "office") as opposed to a treatment room. I remain to be convinced that an ordinary sphygmomanometer is an applied part, in which case the location is Group 0. However, it's use could change and it is probably as well to treat as Group 1.

I think that care needs to be taken with the term, "blood pressure monitor". Part 2:34 of BS EN IEC 60601 applies to equipment which uses a transducer which has been inserted into an artery and is connected by wires. Clearly, that poses a risk in the event of malfunction.

The definition of a sphygmomanometer is very brief in OED: An instrument for measuring the force of the pulse. Strictly speaking, it measures the blood pressure only indirectly. So the pressure which blocks the flow of blood in a cuff around the arm is just above the peak blood pressure (systolic). How such a cuff, which is attached to the medical equipment by rubber tubes, could present a risk of shock is completely beyond me.

I assume that in the consulting room, the consultant will take the blood pressure once (or take the average of two or three readings) rather than monitoring it during the whole consultation. That said, modern sphygmomanometers can take intermittent readings where monitoring is essential (e.g. during surgery).

I venture to suggest that the definition of, "applied part" needs to be reviewed. Clearly, there is a difference between an applied part, which makes electrical contact with a patient, and one which cannot. A good example of one which does is an e.c.g. machine.

The definition of, "medical equipment" can get absurd. For example, your ears feel blocked, so off you go. Doc has a look in your ears with an electrically powered otoscope. Mains-powered ones are available, but most would have a 3 V battery in them. As I read it, the otoscope is an example of an internally powered medical equipment. Doc finds some wax, so removes it with a sucker (nobody syringes ears nowadays) which is connected to a mains-powered pump. Technically, this is an applied part, but there can be no shock risk down a yard or so of plastic tubing. Then you have a hearing test: once again, the headphones appear to be an applied part. It's mad!

I thought that this article is very clear and sensible. So, unless I have misunderstood the situation, your blood pressure monitor is not BF.

Incidentally, I have seen those SEEB sockets many times, but I have never seen one connected to anything; and as you point out, if there is no pin on the ME, it cannot be connected.

My apologies for rambling on, but I hope that this helps.

gkenyon said:

Who classified this as a Group 1 location? For example, 'examination or treatment room' is listed in Table A710, but that is a "list of examples' and the text of A710 says 'Regulation 710.3 cannot be satisfied by using this table alone'.

Specifically, Regulation 710.3 says that medical staff should provide an input, so to assist in classifying the locations ... there are further details in the HTMs as to how the classification is assigned.

Graham, I do not disagree with anything which you have written, but to my mind, examination and treatment are very different.

Classically, a diagnosis requires: history, examination, and (sometimes) investigations. Rather like an EICR: any problems?; visual examination, tug-test, etc.; and application of MFT. It could be done in an igloo.

Treatment is likely to involve something electrical, e.g. application of heat.

As for medical input, I assume that you are referring to an Electrical Safety Group. However, the medics' contribution seems to be limited to saying what will be done using what equipment. If the engineers say that is the use of an applied part, it becomes difficult to assign Group 0.

BTW, I think that the forum is being a bit flaky this evening. GK's contribution was not visible when I made my last one.

Chris Pearson said:

Graham, I do not disagree with anything which you have written, but to my mind, examination and treatment are very different.

That, then, is a comment on BS 7671 (Table A710), and IEC 60364-7-710 (Table A.710.1) ... but they are, after all, only lists of examples (well, prety much the same list of examples).

Chris Pearson said:

As for medical input, I assume that you are referring to an Electrical Safety Group. However, the medics' contribution seems to be limited to saying what will be done using what equipment.

Generally, yes ... and I agree this is not always straightforward ... but I still don't think it's down to the 'designer' on their own, with zero input from the Client.

Chris Pearson said:

BTW, I think that the forum is being a bit flaky this evening. GK's contribution was not visible when I made my last one.

Agreed