New GFCI Tripping Problem

Status
Not open for further replies.
480sparky

480sparky

Senior Member
Location
Iowegia
For the past two years, I've been doing work for a large church that has slowly been installing new furnaces and ACs as they can afford to. Nothing special, just pulling out the old inefficient units and installing new energy-saving ones. It's a simple process from my end.... just disconnect the old units, let the tin-knockers do their thing, then re-energize the new units.

Each furnace (there's 14 in this room) is on it's own circuit, and there's 6 'general' circuits I've used to power up a GFCI next to each furnace for service as well as a condensate pump.

Yesterday, I got word that the GFCIs installed to date are now tripping en-masse. Each one (11 have been changed to date) has a condensate pump plugged in, and it's hard to image them all having a ground fault at the same time. When the GFCIs trip, the pumps don't work, and the furnaces shut down because there's a sensor in them that detects the back-up of condensate.

There's three furnaces that supply the sanctuary that are 'twinned' to one t'stat, and the other day all three GFCI's (2 circuits) tripped together. There's another two that are 'twinned' the same way. No, the furnaces ARE NOT on the GFCI circuits, nor are they GFCI protected. They are all on their own, dedicated 20a circuits.

But the facilities manager is saying that suddenly, several GFCIs are tripping, and they're noticing because it's winter and suddenly an area is 56° or so. Sometimes just one or two, but sometimes 6 or 8. They reset the GFCIs, the pumps kick in, the furnaces turn on, and everything's fine..... until they start tripping again. No apparent rhyme or reason. If it's defective GFCIs, that's would be difficult as the GFCIs have been purchased as needed over the past two years.

Any ideas on what could be causing this? I
 
So the common denominator is the same model of condensate pump?


Can you hardwire them through a disco and eliminate the GFCI protection for them? Not recommending that yet, but throwing it out there.
 
I would ask the facilities manager the following question: "Can you rule out malicious mischief"?
 
LarryFine said:
I would think there would be no condensation during heating.
Click to expand...

The new high-efficiency furnaces do indeed have condensation in the flue. SO MUCH heat is extracted it drops its moisture* in the flue, which can now be made out of PVC instead of double-walled steel.

I get lots of issues from condensate leaks in these systems, in attics... :rant:

*And remember there is far more moisture in the flue than ambient because water vapor is a combustion product.

OP says the condensate receptacles are also serving as the service receptacles for the equipment, so those probably need GFCI protection. But, in the same vein, can additional simplex (or duplexes serving two pumps) be added that are not protected, just from the line side of the existing GFCI receptacles?
 
charlie b said:
I would ask the facilities manager the following question: "Can you rule out malicious mischief"?
Click to expand...

I doubt that's the case. Especially when the 2 / 3 units that are twinned trip at the same time. I don't think your average Bart Simpson is going to trip 'just those three'.....
 
480sparky said:
I doubt that's the case. Especially when the 2 / 3 units that are twinned trip at the same time. I don't think your average Bart Simpson is going to trip 'just those three'.....
Click to expand...
We are still at the "when you eliminate the impossible" stage that you have to get through before you reach the "whatever remains, however unlikely, must be the truth" stage.

 
charlie b said:
We are still at the "when you eliminate the impossible" stage that you have to get through before you reach the "whatever remains, however unlikely, must be the truth" stage.

Click to expand...

Well, I can't eliminate the possibility that Elvis is living in the ducts and comes out at night to make a fried peanut-butter and banana sandwich either.
 
480sparky said:
Yesterday, I got word that the GFCIs installed to date are now tripping en-masse. Each one (11 have been changed to date) has a condensate pump plugged in, and it's hard to image them all having a ground fault at the same time.

Any ideas on what could be causing this? I
Click to expand...

MAC702 said:
So the common denominator is the same model of condensate pump?
Click to expand...

I kind of like the common denominator idea ( now if I only knew what it ment ).

I really don't have much of a problem with the idea that all those condensation pumps could be ground faulting.

They probably need to run for a certain amount of time and heat up before faulting. There has been a lot of moisture in the air lately. You could experiment by adding your own water to keep the motors running and see what happens. Or just check with the manufacturer to see if they have complaints about them tripping GFCIs.
 
Measure the leakage / differential current

Measure the leakage / differential current

When a person has an issue with GFCIs I always recommend that the leakage current be measured.
That way you can gain an understanding of whether it is a completely transient condition - or if you are always leaking enough current to be on the edge of tripping all the time.
You can also then monitor when the machines are in different stages of their operation to better understand what the largest contributor to the leakage current might be.

I thought I recalled a requirement on some high efficiency units to have a good ground due to the fact that some current returned on the ground?
 
ELA said:
When a person has an issue with GFCIs I always recommend that the leakage current be measured.
That way you can gain an understanding of whether it is a completely transient condition - or if you are always leaking enough current to be on the edge of tripping all the time.
You can also then monitor when the machines are in different stages of their operation to better understand what the largest contributor to the leakage current might be.

I thought I recalled a requirement on some high efficiency units to have a good ground due to the fact that some current returned on the ground?
Click to expand...

The furnaces are not GFCI'd.
 
Thought: might these new furnaces have electronic ignitions that are causing the GFCI's to trip?
 
Must be a large church!
I had a similar issue with 1/4 hp submersible pumps, by little giant, used for water sampling. Pump would trip GFCI, it was an "electrical issue", operators changed the pumps, perhaps 3 in a row over some months. I would dunk the pump in a bucket of water and it would meg low enough that the GFCI would trip. Call to the mfg, and issues with your pumps? "no". Operators didn't quite get ohms law...and of course the GFCIs were replaced
Been ok for about a year now.
Can you try a different model condensate pump?
I am very confident its not a GFCI issue, it its tripping its doing its job.
Once I saw a sample pump trip the GFCI, bad GFCI the operators said! Well one of them had spliced the pump cable, water leaked into the motor, dead short to ground, and the GFCI was doing its job
What about a 30 mA trip GFCI?
 
Status
Not open for further replies.
Top