At another property....I discovered both garage door opener outlets are on the load side of a GFCI mounted elsewhere. In fact, I think all the garage outlets are on the GFCI load terminals, including a freezer. I know this is a common way to GFCI protect outlets downstream, however I am concerned.

It used to be in the past that motors set up on a GFCI load caused the GFCI to nuisance trip.
My question is whether this is still holds true? Or are the newer GFCI outlets less likely to trip this way?

I am considering having the door openers removed from the GFCI load side because I am concerned the tenants will lose power to the door if they default on using that for house entry--hence they get locked out.

The other thing is, it seems with the latest NEC code--so many more things are required to be on GFCI circuits....like garbage disposals, washing machines, etc. Do you find nuisance tripping going on with these motor/appliance situations?

Thanks in advance for your help!

 

No, motors generally do not trip GFCI. My house, built 20 years ago has all garage outlets GFCI protected. With three openers, chest freezer, full size fridge, dehumidifier and countless hand tools plugged in I've never had the GFCI trip.

 

PD, explain.
I thought that a GFCI protect against an over draw of current in addition to shorts or ground faults. Motors typically draw a high start up current. So theoretically if all garage openers and freezer compressor, dehumidifier and maybe your drill all stated at the same time would that not trip the circuit? Even any combination of these appliances? Isn't that why appliance manufactures always specify a dedicated circuit for microwaves, dishwashers, refrigerators, freezers, sump pump etc...and most motor driven items?

 

Having some knowledge on this, I'm going to pose an answer Norm. Others may expound also. First, I'm not worried about the GFCI tripping from over current, or the breaker tripping. My concern is the GFCI itself nuisance tripping from the motor start ups. I know for certain this was a problem with the older GFCI's going back 20 years or more. I'd see vacuum cleaners trip them, etc.

The GFCI's would trip from the motors inductive kick, or something like that, upon start up--not over current. Not sure if I have this technically correct, so I hope others will input on the history of this problem. Seems the newer GFCI's do not nuisance trip as much.

Secondly, dedicated circuits--appliance motors maybe rated a dozen or so amps, but the start up current can be many amps more, which can trip a breaker if other appliances also share that circuit. Hence the need for dedicated circuits. I'm not sure the GFCI would trip first from over current in this case anyway, maybe I need clarification.

In any case, my primary concern here is the nuisance tripping of the GFCI, not over current trip potential.

 

I have only seen one reliable condition that caused a motor induced GFCI trip. It was on a boat davit with a plug -in cord. The cause was a intermittent 3rd pin connection to the green cord wire. That was 20 years ago, nothing since then. Currently running GDO, dishwasher, etc on GFCI, and no nuisance trips. AFCI's are another story altogether.

 

Gen, we are in fact humming the same tune. If I'm not mistaken that motor start up kick is in fact a momentary rise in current draw. I can actually hear it and see it when running on generator power and any appliance kicks in. The ammeter on the transfer switch will bounce way up then fall as the appliance starts and runs.

Also this...from the internet-"Remember, there is NO SUCH THING as nuisance tripping when it comes to a GFCI device, no matter what any 'expert' tells you. If the appliance is tripping a GFCI device and the GFCI device is testing as OK, then you need to address the problem with the appliance before using it any further."

And this..."Ground faults occur when electrical current finds an unintended path to ground. ... The insulation protecting longer conductors has higher capacitance, which can cause even more leakage current. On GFCI-protected circuits, leakage current can cause unnecessary and intermittent tripping."

The above might be what your concerned about. If it hasn't happened yet, then I doubt it ever will. Either the conditions is present or it's not.
With that revealed I'll correct my rebuttal to PD and agree that a GFCI should not trip due to too many items on the circuit. The breaker may trip but not the GFCI or for the particular reason of too many items.

I'm open to correction or clarification if need be. I'm not an electrical wizard as previous post of mine have shown.

 

OK useful Norm Thanks. So if I understand some more things
--It may be the appliance insulation or age/degradation that causes a GFCI trip.
--Excess conductor length can cause a GFCI trip? I have heard something about really long extension cords causing nuisance trips? Anyone heard of this?

 

It's possible. So, in tek speak, the GFCI is sensitive to "common mode" currents, but not "normal mode" or "differential mode" currents. When you have a length of L, N, and G conductors in close proximity, you will have L to G and L to N capacitive currents. L to N, being normal mode, will not be a factor. However, that L to G current is not balanced by a corresponding N to G current, since there is no voltage differential there.
So, that leaves two items to consider. What is the capacitance from L to G? The larger the conductors, the longer the length, and the thinner the insulation will all contribute. Xc= 1/ 2pi*60*C.
The second point would be what algorithm the GFCI uses. If it ignores capacitive current, which is out of phase from resistive current, this stray capacitance may not be a factor. One could easily test this by applying a capacitor from L to G, that will draw 10mA. If it trips the GFCI, then it IS sensitive to capacitive currents, and a sufficiently long run could trip the circuit.

 

Interesting...thanks for the info TC

 

Not so! A GFCI device does not trip on current overload. They only trip when there is a loss of 4 to 6 mA from hot or neutral side of the circuit.

 

OK so help me understand...I have seen several instances where a GFCI will trip from a power surge. One instance was when a transformer was lost. A few others instances occurred when power was restored after an outage.

 

And I lost one, permanently, due to a lightning strike. GFCI’s, being made up with semiconductors, have limitations. Exceed the ratings, and bad things happen.

 

I think the best solution is a non-electrical one. If the power goes out and there's no other way into the garage, a key-operated release works well as an emergency backup. Something like this:
https://www.homedepot.com/p/Prime-Li...2143/202633678

There are of course battery backup garage door openers too.

My experience with GFIs and motors though are similar to your other responses. The only times I've seen a motor trip a GFI is when it was on its last legs and on its way out. I would rather have a solution to handle power outages and a random GFI trip, rather than just focusing on the possible GFI trip issue.

 

GFCI devices, both receptacles and breakers, are electronic devices. Surges are high voltage and high voltage many times will trip or permanently damage a GFCI. Like telecom guys said, "Exceed the ratings, and bad things happen." Surges have absolutely nothing to do with overcurrent.

 

I didn't see it in any of the other posts but, garage door openers are required to be GFCI protected by the NEC.

 

Yes I understand they are required GFCI protected via NEC. But I'm thinking...what purpose does it serve to protect an outlet on a garage ceiling?

And the downside to me is that will increase the likelihood that the occupant gets locked out if it trips and the door can't open.

 

My understanding is that many homeowners were using it as a receptacle to plug in christmas lights, other appliances, etc... where the GFI protection was necessary.

 

In our law suit society manufacture's will protect themselves for any possible liability. Most appliances are demanding dedicated circuits.