Surge Suppressors and GFCI Outlets

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Peanut

Peanut

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APC makes quality UPS and Surge Suppressors for home use. I ran into a problem connecting an APC surge suppressor to a quality Generac 8KW generator. With almost no load the surge suppressor kept causing GFCI outlets on the generator to trip. Given the circumstances, all pertinent facts, led me to believe there was an issue with the surge suppressors in general and GFCI outlets.

Searching the APC website revealed the following information. It seems I was right, surge suppressors can cause GFCI outlets to trip. The problem happens instantaneously. On power up something in a surge suppressors design causes the current sensing of the GFCI to see a short where none exists.

BUT... not all GFCI outlets are susceptible to this problem. This statement by the company APC (on their website) that mentions this issue.

https://www.apc.com/us/en/faqs/FA158850/
GFCI circuit breaker trips after UPS or SurgeArrest
Issue:
GFI outlet, circuit breaker trips after UPS or SurgeArrest is connected.

Product Line:
Back-UPS Models ES,CS,NS,XS and RS. Surge Surpressors; All Product Families

Environment:
Surge or Back-UPS plugged in to GFCI outlet.

Cause:
A ground fault interrupter (GFI) is a safety device required by the National Electrical Code. Its purpose is to avert personal injury. Some GFI devices are poorly calibrated and trip prematurely.

Resolution:
You can try to replace the GFCI device and see if this solves the problem. Try a different brand if possible. If the outlet is not in a bathroom or kitchen, you can consider changing the circuit to a non-GFCI receptacle or breaker. The circuit breaker type GFCI devices are generally of higher quality and are recommended as being more immune to this type of problem.

@Neb @dademoss
 
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I found the following on the net. It's a decent description of how a surge suppressor works. Basically, a suppressor diverts a spike of electricity to ground.

When any electrical connection is made, say turning on a light switch there is ALWAYS a power spike into the uncharged circuit. It may be a very small spike, almost minuscule but it does exist. I have seen these spikes measured on oscilloscopes many, many times. I actually worked on a test using a dozen types of switches looking for the type that produced the smallest power spike to solve an issue in an experimental patient table (part of a catscan).

Anyway...

1) By design, a suppressor will divert a voltage spike over a designed threshold to ground.

2) A GFCI outlet is designed to sense a short in the current flowing through it. It also has a design threshold, what it "see's" as a short and will trip cutting off the flow of electricity.

In a world of comedies... The GFCI outlets on my Generac generator are working as they are designed to work. The APC surge suppressor I plugged into the generator is working as it is designed to work. In my case the design threshold of these units are overlapping.

Also, when I was tripping the GFCI outlets the other night the surge suppressor was the only load on the generator (but devices were plugged into it). I think that if the generator were heavily loaded the voltage spike seen by the suppressor would be smaller and would not cause the suppressor to divert the spike to ground. This would explain why I've turned on the suppressor in the past while connected to the generator without issue, the generator was loaded.

That would be one experiment to run... another would be plugging in the suppressor while nothing is plugged into it, no load but the suppressor itself. Again, the spike should be minuscule. Then plugging devices into the suppressor one at a time to see if one of them pulls enough power to cause a spike.

How Surge Protectors Work
“When a sudden increase in voltage occurs, such as from a lightning strike or damage to a power line, a surge protector detects the excess current and safely diverts it through the house’s grounding path.” A simple statement and it sounds great, but what does it mean? How does a surge protector know how to do this? To understand that, we just need to simplify a little terminology...

The Vagueness of Electrical Vocabulary
Understanding voltage and amperage can help you better grasp how surge protectors work:

Voltage:
Using the analogy of water in a hose, voltage is the equivalent of electrical pressure.
Amperage
Using the same analogy, amperage is the flow rate, or amount of fluid running through the hose.
Surge Protectors: Excising the Excess
Using our trusty hose analogy, applying too much pressure in a hose can eventually cause it to burst. In the situation of electrical excesses, however, rather than bursting, electrical lines and appliances burn up, or at the very least wear down over time. By diverting excess pressure in the hose (your home’s wires) surge protectors safeguard wiring and appliances. To accomplish this, they need the help of special components.

Managing the Pressure
How is all that pressure, or excess electrical energy, diverted? When voltage reaches a certain point, surge protectors simply re-route that extra energy with the help of what is essentially a pressure-sensitive valve. With the correct voltage, current flows through as normal, but with a spike or surge, the device kicks-in immediately and redirects the excess. Commonly used devices for managing this pressure in surge protectors include metal oxide varistors (MOV) and gas discharge arrestors, which allow electrical devices to continue operation while diverting excess energy to grounding wires
 
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Look up 'MOV's (Metal Oxide Varistors) as - Imo - (theory, here..) it's the "surge suppressors" with MOVs as their 'surge suppressors' (most common, as they are a cheap-way to achieve that) that tend to trip GFCIs..

That said.. GFCIs are a 'PITA'.. :) I get Why they are of value, and all, but.. Such a shame that 'Nikola' met an early, and nefarious, demise.. I am sure that, had he Not been 'offed', he would have come up with something Better.. :cool:

jd
 
You're probably right. It's been 20yrs since I've really dug into the hardware side of a problem. I had to spend a couple days shaking the cobwebs out just to remember how suppressors work in general terms. I used to work with power conditioners that handled 3-phase 480vac, basically a higher tech version of a household surge suppressor.

Anyway, I knew the problem I had the other night had to do everything to do with how GFCI's and suppressors would work together. Logically I thought there was a ground issue, but my gut said GFCI/suppressor, just didn't remember why.

I thought I'd start this thread because it is a tricky problem. Make folks would think something was broken (including me at first)... When nothing is broken, just a mismatch of components.
 
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In our off-grid setup, I use three APC "smart-UPS" devices to protect all sensitive computer electronics ... they buffer these electronics (computers, networking gear, tv's) from any kind of power blip from inverter/generator/etc. These are higher-end units, equivalent to what would be in an IT shop somewhere to protect a server; bought them used, threw in new batteries, and they've been good ever since.

I do notice that the UPS's "click" when they are sensing any kind of power fluctuation ... a microwave or other high power device kicks on, or the generac starts up via the inverter.

We have GFI's at certain locations (bathroom/kitchen counters, etc.), but none of the UPS's are on a GFI ...

We do our own electrical work, and GFI's tend to get replaced faster than non-GFI's ... they seem to be more sensitive and short-lived ... haven't found a dependable brand yet. I've taken a dead one apart, but can't visually spot a failing component on their circuit board ... don't know what's causing them to die off.
 
I have a generator that has extremely sensitive GFI's, in order to use e it a few winters back I had to use the 120/120/240 VAC outlet connection only using just one 120 connection, the regular duplex 120 VAC GFI outlets tripped out. Since putting our solar backup system into operation, we've not needed the generator. I just installed two EMP Shields, one on the incoming grid breaker panel and the other on the solar array power coming into the solar controller, any GFI's are on the output side of the grid panel and the inverter output doesn't require GFI's.
 
I am not sure what help I can offer without a storage scope and details of the GFCI and the surge protector.

I had whole house surge protection installed with my service entrance to protect from power line surges since The Princess was running about 5 servers at the time. All electronics are plugged into passive surge protected power strips or UPSs.

The kitchen and bathroom outlets are all GFCI outlets. There is one circuit breaker GFCI for an outside outlet.

In none of those layouts do I have a GFCI feeding a surge protector.

2 stories reported to me.
Brother tried to run a new power washer plugging it into a GFCI. He kept tripping the GFCI. Plugged it into a different GFCI no problems.

Son had a pool pump which I BELIEVE had a GFCI built into the power cord. It repeatedly tripped a GFCI I helped him install on the outside of his house. His father in law decided to cut of the GFCI of the pump and installed a new plug. That sopped the tripping.

So it seems the details of the GFCI are needed to understand why they are tripping.

Old school operation...

Good quality passive surge protectors used big inductors in series with the hot and common lines and a capacitor between each line an (?) ground. A spike would have high frequency components to which the inductors would look like high impeadence blocking the spike going to the load while the caps would provide a low impeadence path to ground. Mind you these were the big heavy surge protectors rated in how many Joules of energy they could absorb.

Old GFCI would use a pair of coils one for the hot and one for the neutral line. When the current through both coils was the same they would balance each other to prevent a trip. I there was an unbalanced current in the coils it would trip the GFCI. The imbalance could occur if current was flowing in the ground path instead of neutral path.

Modern GFCI most likely use electronics instead of coils.

Speculating...

With no load plugged into the surge protector will it trip the GFCI?

Is the surge protrctor passive or is it a UPS?

If it is a UPS is the battery fully charged when plugging it in?

Generally...

GFCI are intended for use around water like kitchens bathrooms and outside.

Surge protectors are to protect sensitive loads.

I suspect you may know much of what I posted but added to that word salad to help the non technical reader.

Ben
 
In the last 24hrs I've learned that quality and consistency are foreign words in the GFCI world. They are all over the place where reliability is concerned. Basically they are made to protect idiots who drop their hair dryer in a sink full of water. Other than that they have no real use. But one...

Someone somewhere is making a boat load of money from them since they managed to get them into every building code in the country.
 
Peanut said:
In the last 24hrs I've learned that quality and consistency are foreign words in the GFCI world. They are all over the place where reliability is concerned. Basically they are made to protect idiots who drop their hair dryer in a sink full of water. Other than that they have no real use. But one...

Someone somewhere is making a boat load of money from them since they managed to get them into every building code in the country.
Click to expand...
There are idiots in every part of the country and lawyers happy to help them so...

Ever read the safety warning instructions for the lanyards used hang a photo ID around your neck?

Not intended for children under...

And why some lanyards have break aways built in.
?

Ben
 
My parts oven tripped the GFCI outlet if it was turned over just barely on. I checked the oven for shorts and found none. I plugged the oven into other GFCI outlets with the same result. I used a standard outlet and it works fine.
I decided that the GFCI outlets were only rated for 15 amps when they were all supposed to be 20 amp outlets. It all works now and the new outlet is mounted on the ceiling instead of the wall so the code is satisfied.
 
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