Hospital Grade GFCI Receptacles Tripping

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Desert Sparky

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Long time lurker here, first time poster.

The project is a medical facility that has been operational for less than two years, but has ramped up its use within the last six months. With this ramp up, the user has reported an increase in random tripping of GFCI receptacles in a couple of specific rooms. Some background on what we've discovered so far:

- The tripping has been completely random, and we've not been able to identify a specific piece of equipment as the culprit.
- Tripping seems to occur at start-up; for example, the user will plug something in, hit the "on" button, and seconds later, a trip.
- The electrician has tested receptacles and confirmed no issues with branch circuitry/installation. They've even replaced all of the receptacles in the rooms, but some of these receptacles have tripped as well.
- GFCI receptacles in other rooms have not experienced issues; the rooms with the issues are fed from a panel that is dedicated to the rooms (the panel feeds no loads outside of these rooms).

This one has been a real head scratcher, so any feedback/input would be appreciated. Has anyone seen line side power issues causing a GFCI to trip, or can the issue only be on the load side? Thanks in advance!
 
ptonsparky said:
Inductive loads cycling on the line side of the same circuit can cause grief.

Sometimes a different brand will work.
Click to expand...
In some instances, the equipment is plugged into a dedicated circuit, so no other loads share the circuit. Can inductive loads on a different circuit in the same panel, or perhaps even a different circuit connected to another panel in the facility, cause this issue?
 
High frequency switching from electronics, drives, power conversion equipment, etc. can be a problem for GFCI as well.

Usually has to be on load side of the GFCI but occasionally something on line side causes problems.
 
Can you use a GFCI breaker instead? Sometimes GFCIs trip due to RFI and not due to a ground fault. Using a breaker will move the sensitive electronics further away.
 
CoolWill said:
Can you use a GFCI breaker instead? Sometimes GFCIs trip due to RFI and not due to a ground fault. Using a breaker will move the sensitive electronics further away.
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I like this idea, but it would be good to know this is what's causing the issue before we start buying a bunch of new breakers. Is there a way to test for this?
 
Random tripping of hospital equipment means there is an issue with the equipment (lead Supervising electrician for 3 hospitals).
I have regular tripping of equipment in dialysis, as mentioned above gfci’s don’t play well with motor loads, I have several areas where thermal units with fans trip GFCI’s, the more heavily loaded that circuit is the more likely to trip.
We regularly test all GFCI’s in the hospital,
1 time a year we even verify the 6 ma trip
Whatever you do don’t waste your $ or time on the RT390 by Klein tools it is a piece of junk. I purchased 1 to evaluate for plant engineering to do the real checks, every GFCI I tested would have had to be replaced by code as this “tester” said the trip value was 8ma /code is 6ma.
I provided the info to Klein I did not think they were going to post my review, they finally did I sent them many pictures I never had a GFCI pass. Using a little 3 light tester with a test button is better a Hubble GFT-2G works ok but you have to measure the values on each of the 6 resistors (range from 60.5k-17.41k)
There are much higher end testers but the minimum is the simple test button on the GFCI
You then need to verify the hot opened.
Remember since 2004? GFCI’s have been mandated to have self test functions, if this works the GFCI is good, I have been monitoring the power with a fluke 1777 on the dialysis main and had trips with no issues of transients sag or bumps and measurements of harmonics to the 50th? Those values were 1/2 of acceptable limits. So I know it is the equipment being motors, and switching supplies as the leading issues.
 
Desert Sparky said:
I like this idea, but it would be good to know this is what's causing the issue before we start buying a bunch of new breakers. Is there a way to test for this?
Click to expand...
I would not suggest GFCI breakers especially in a hospital, in a hospital the device is needed to be reset quickly and panels in public areas are required to be locked, most are in locked electrical closets. some areas, Like PACU / recovery can have a receptacle right next to a sink and since it is used for life safety equipment no GFCI is required, when I came to the hospital I was ready to swap them all over to GFCI until doing more foot work, it is possible of MWBC are in use this could be another possible cause (my main hospital is 208/120 3 phase but I have not seen a bump in the ground or neutral currents or voltages when monitoring
If the caregiver or provider insist there is a problem require the system to be full cycle tested and monitoring of the unit by Bio medical techs. They regularly find very minor issues that combined may be the root cause.
 
I am serious about P&S. I have done quite a few cafeterias and food courts. We had a project at a University where some of the counter top equipment would trip GFCI's on start up and when shutting down. One of the kitchen equipment installers said P&S would fix the problem. He had a few with him so we installed them and sure enough no more trips.
 
Desert Sparky said:
I like this idea, but it would be good to know this is what's causing the issue before we start buying a bunch of new breakers. Is there a way to test for this?
Click to expand...
You have to be careful with breakers also. Any time you have a circuit length longer than 100 ft one way, you can get capacitive imbalance that causes neutral tripping.
 
Thank you again everyone, really, all great feedback. I am definitely considering recommending P&S receptacles; maybe we'll start with a couple of locations at first to see if there is any difference.

Circling back on the inductive loads on the line side of these receptacles, does anyone know if Inductive loads cycling on the line side of the same circuit is the only thing to consider? Or can inductive loads on other circuits in the same panel, or in other circuits in a different panel, work its way down to the receptacles in question?
 
It isn't really inductive loads that affect GFCIs anymore. That seemed to be the case 40 years ago when a home refrigerator or something might cause a GFCI to trip. Today, it seems to be electrically noisy loads that incorporate variable frequency motor drives or other equipment with chopper type power supplies.
 
roger said:
One of the kitchen equipment installers said P&S would fix the problem. He had a few with him so we installed them and sure enough no more trips.
Click to expand...
Hmmm. You don't suppose P&S puts surge suppression (and noise filtering) of their own on the LINE side of their GFCI receptacles? That way surges and spikes are caught before they go through the GFCI to any SPDs plugged into it which would trip the GFCI.

-Hal
 
I don't know but it seems that would put them in a different price range but who knows.
 
Almost all modern electronics now use Switch Mode Power Supplies, and many of those are designed with very poor filtration for the high frequency "common mode current" that happens as a natural consequence of of how they function. It happens on ALL of them, but if the INDIVIDUAL device emits less than 1mA of CM current leakage, they think that's fine. But put 6 devices like that on a GFCI circuit and you have 6mA, which will trip the GFCI. Part of the problem is that the GFCI algorithms are not required to discriminate between leakage current at the fundamental frequency (60Hz) and that of the SMPS, which can be at 15kHz or more. SOME of the GFCIs do a better job of that, some do not, but it is NOT a requirement so it is not considered a "design deficiency". There isn't a lot that can be done about it, at least until there are standards enforced on either the GFCI manufacturers to incorporate HF discrimination on the leakage current sensing, or the power supply manufacturers to include better filtering (or both).

In the mean time, about the only thing we can do is to swap out BRANDS of GFCI devices until we find one that is compatible with the specific load involved. Changing an outlet for a new one of the same brand is not going to help, they will have the same algorithm and sensing elements. A couple of people here and elsewhere have also mentioned that some high-end "Surge Protection Devices", those that incorporate inductors and ferrite cores as part of their design (not just some MOVs), are able to help mitigate this, likely by dampening the HF CM noise components of the waveforms. I have no proof of that, just anecdotes. But it might be worth trying.
 
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