Sorry if this has been answered before but after search I can't find an answer.
What constitutes a medical system?
We have a new colposcope which is a class 1 from which the light and low voltage go to the microscope. Between the power supply box that produces the light, and the microscope is a stand with arm attached and the box is attached to the vertical shaft of the stand and the microscope to the other end.
My issue is that there is no bonding between the box and the stand and the touching parts are powder coated metal. Should there be bonding between the 2 according to regulations????
Just because you see some conductive part does not mean it is required to be protectively earthed. Conductive parts not intended to be protectively earthed only have to meet the touch leakage current requirements of IEC 60601-1.
Regardless of "chapter and verse" of various regulations, if I had come across a situation like that I would have provided an earth connector to the stand (frame); thus simplifying matters for future generations of tests (at least).
No doubt someone will now come on here shouting ... "but that would be a modification"; to which my reply would be ... "I only care about patient and user safety".
By the way, does the unit pass EST checks at it stands? Where do you (your electrical safety tester probe) find its "earth"?
Geoff, please explain why you feel the need to get out a drill to add earth wires and modify a medical device? If those conductive parts meet the touch leakage current requirements where is the hazard? Mains can't pass through the earthed enclosure of the power supply box. After all the only earth you can use is the PSU box anyway. Unauthorised modifications can and do often compromise patient safety.
OK Mike, maybe my reply had been a bit "tongue in cheek"; and (to be honest) I had missed where Seadog had already mentioned that the kit was new (I had imagined something a bit older, and probably rougher, like ones I have come across in the past).
In my experience, the real electrical hazards were often to be found lurking in the "forgotten areas" (such as satellite clinics, hospital Outpatients Departments, secret cupboards on the wards and what-have-you) ... that is, rather than on modern equipment in the "high-tech" areas. I have in mind "traditional" items of electromedical equipment such as (for example) Bullnose Examination Lamps, ancient cautery sets ... and even colposcopes.
To return to the case in point, I would need to examine the item, and maybe get my multimeter out to run a few tests. As this is new equipment, if (during acceptance testing) I wasn't happy about the state of it, I would take it up with the supplier in the first instance; otherwise I would indeed be ready get the tools out again!
PS: we haven't yet learned the results of Seadog's EST checks.
Thank you for your reply. As a stand alone item it does indeed pass the class 1 EST test. I have attached a photo of the equipment. The screws attaching the device to the shaft are earthed. This is now a 'system' as I understand it.
I know very unlikely but if a bare wire should touch the arm there is no path to earth.
First of all, that's a far nicer looking piece of kit than the one I had imagined.
No doubt the manufacturer's label (partly obscured in the first image) says all the right things. Any chance of posting a picture clearly showing the label? Also, what (if anything) does the manual have to say? Any declarations about electrical safety?
The second picture shows what appears to be a white mains cable coming into the box. Is that a Y-split? If so, what is that all about? Is the cable detachable at the box end? I'm guessing the the red and black leads are part of your test kit!
So, the screws you mention are earthed. So that must be where you poke the tester probe, then. I assume that the black foot control is for the 'scope (and camera?). That connecting cable doesn't look very robust. Best get a spare in stock straight away!
Meanwhile, what else is in that medical room? Is the chair earthed? What's that other kit? ESU's? Suction? Any equipotential studs on the wall(s)? Any anti-static wheels, tubing etc. in evidence?
Lastly, consider how things will be there in a few year's time. Think fluids, rust, scratched paintwork etc., etc. As I have hinted at before, personally I would like to have "everything" in there to be at the same potential. That is, earthed.
Single mains cable, white and fixed, and black cable to recorder. Foot control for the chair. Screws are earthed and equipotential post is underneath where the mains enters.
I just want to know if it is classed as a system and if it needs to be bonded to the stand according to 60601.
OK, various documents offer an interpretation of the meaning of "system" according to IEC 60601-1. I quite like the one found here.
Quote
Combination of equipment in which at least one is classified as medical electrical equipment and is connected by functional connection or use of multiple portable socket outlets.
If we agree that is a sound definition, with the key word being "combination", then I would say that your colposcope is not a system as such, but rather a single item of equipment.
An example of a medical equipment system that I usually like to suggest is that of the "theatre stack" - insufflator, camera unit, printer, suction etc. all sitting (in "combination", or "functional connection") on the same trolley, and typically fed from a multiple socket outlet powered from a single cable (plug).
Regarding the need to be bonded to the stand, I can't see that 60601 specifically requires this; although my personal opinion has already been offered.
It is not a system. it is a single piece of medical electrical equipment. All parts form a single piece of ME equipment. If you were to add something to the equipment, such as fixing a UPS to the stand, then you would be creating a system.
