OSHA cites for GFCIs used in series

[Sharpie]

Our insurance Rep. told me that OSHA is citing for plugging an extension cord into a GFCI and then also using a portable GFCI at the load.
They are claiming that the GFCIs will interfere with each other somehow.

I've asked our insurance Rep. for some documentation stating that (and the technical description of what they are claiming).

I don't understand how the GFCIs would keep each other from working.

Does anybody know why this might be, or what OSHA is trying to do here?

Thanks,

 

[Pierre C Belarge]

Chris
Maybe your insurance contact has the wrong information.

 

[hillbilly1]

I've heard this going around, I think it's just an urban legend. I wonder if Snopes has checked it out!

 

[K8MHZ]

Could it be (I'm just thinking out loud) that when they are in series it takes more current to trip one of the devices as the fault current is shared by the two devices in series? Other than that what could be the issue?

I think it's time to get our handy little testers out and see for ourselves.

 

[zbang]

Could it be (I'm just thinking out loud) that when they are in series it takes more current to trip one of the devices as the fault current is shared by the two devices in series? Other than that what could be the issue?

Since GCFIs trip via current imbalance, it wouldn't make any difference how many devices are in series. The fault current isn't 'shared', remember that long discussion of whether or not a ground is required? If I-in <> I-out, it trips.

 

[JohnJ0906]

The only issue with 2 GFCIs in series, would be the inconvenience of resetting the 1st one before the 2nd one if they both trip.

If there is a ground fault, one or both will certainly trip. There isn't any safety issue with it that I can see.

 

[K8MHZ]

Since GCFIs trip via current imbalance, it wouldn't make any difference how many devices are in series. The fault current isn't 'shared', remember that long discussion of whether or not a ground is required? If I-in <> I-out, it trips.

Well, technically they aren't in series, they are connected in parallel like any other device. To truly be in series would take some creative re-wiring.

 

[K8MHZ]

To wit,

In a parallel circuit the voltage is the reference and the current is divided. I won't say for sure without doing some testing myself if my suspicion is accurate or not, but I could see someone looking at a diagram of two GFCIs and doing some math and thinking there may be a problem.

Anyway, what would be the point of doubling up on the protection devices, anyway?

 

[Sharpie]

There may be times that you would plug into a GFCI protected receptacle and not know it is protected.

I personally don't see the point in the double protection, but it may be someone's SOP to always use their portable device. Just a thought

 

[Pierre C Belarge]

There may be times that you would plug into a GFCI protected receptacle and not know it is protected.

I personally don't see the point in the double protection, but it may be someone's SOP to always use their portable device. Just a thought

The GC may ask his electrical contractor to provide GFCI protection. One of the trades then plugs their GFCI protected cord into the GFCI device. Very common on jobsites.

How about a contractor working outside and plugs his GFCI protected cord into a GFCI protected receptacle...again, happens all the time.

 

[zbang]

Well, technically they aren't in series, they are connected in parallel like any other device. To truly be in series would take some creative re-wiring.

Since there is only one path for the current, I'd call it a series circuit. In a parallel circuit, there would be multiple paths, and you can't have that if a portable GFCI unit is plugged into the protected side of another GFCI.

 

[K8MHZ]

Since there is only one path for the current, I'd call it a series circuit. In a parallel circuit, there would be multiple paths, and you can't have that if a portable GFCI unit is plugged into the protected side of another GFCI.

So the current is the same everywhere in the circuit no matter if the size of the loads vary? Remember, current is the unchanging reference in a series circuit and instead will exhibit varying voltage drops across loads of varying sizes.

Anytime the voltage is the reference you have a parallel circuit. It doesn't matter what it looks like on paper, if the current changes and the voltage stays the same across the loads, you have a parallel circuit.

 

[jim dungar]

GFCI's are installed in a circuit that is intended to be series (i.e. what goes out the black wire must come back on the white wire) connection.

The GFCI is supposed to trip if the intended series circuit accidentally(?) becomes a parallel circuit (i.e what goes out is not equal to what comes back in).

One GFCI plugged into another GFCI creates two devices in series. The number of parallel or series loads is immaterial, because as far as the GFCI's are concerned the entire load looks like a 2-wire 'black-box'.

 

[LarryFine]

Our insurance Rep. told me that OSHA is citing for plugging an extension cord into a GFCI and then also using a portable GFCI at the load.
They are claiming that the GFCIs will interfere with each other somehow.

I suggest having whoever enforces the use and operation of GFCI's on the jobsite use whatever tester they use and show you that two GFCI's reduce the effectiveness of the testing device.

In other words, when they say that two in line don't work reliabley, simply say "Okay, whip out your GFCI tester and show me."

 

[K8MHZ]

I suggest having whoever enforces the use and operation of GFCI's on the jobsite use whatever tester they use and show you that two GFCI's reduce the effectiveness of the testing device.

In other words, when they say that two in line don't work reliabley, simply say "Okay, whip out your GFCI tester and show me."

GFCI testers don't always work. Try one in a GFCI circuit with no grounding conductor. FAIL.

The only approved means for testing fault protection devices is the test button on the device. Is it the best way? I challenge that as I feel that is the fox watching the hen house and I know how to make my GFCI testers work with or without an ECG provision. I have an adaptor that allows me to ground my tester to a known good ground which allows it to function on two wire systems. A bit more fussing around, but provides reliable results.

 

[LLSolutions]

I'll try to put this to bed, I have a functioning GFCI in my bathroom, I use a greenlee meter that has a lamp that can be switched on to put load on the circuit. Doesn't have to use the ground, I tried it from hot to the faucet also. I confirmed the bathroom one worked, then plugged a gfci cord in and tested that too, the cord tripped first every time but works fine. While in the bathroom I also remembered, don't hair dryers all come with gfci cords?

 

[brian john]

How about my bathroom and the wife's new hair dryer.

Where's Jamie and Adam. AKA Mythbuster's

 

[goodcode]

A citation was issued in this case due to the marking on a portable GFCI device. An individual was using power from a hard wired GFCI receptacle outlet using an extension cord. He used a portable GFCI device as a splitter at the end of the extension cord. The portable device is marked to instruct the user to place the portable GFCI at the receptacle outlet. This marking exists on a portable device to ensure that the extension cord is also provided with GFCI protection. The marking however, applies only when the portable GFCI is the only GFCI protection provided.
There is no problem. There was no hazard. The level of protection was increased due to the open neutral protection provided by the portable GFCI device.
OSHA is removing the citation.
It should be noted that when a portable GFCI device is used on a non-GFCI protected circuit, it must be plugged into the receptacle outlet upstream of the extension cord or a valid citation will be issued.

 

[brother]

Ive heard this 'story' too. Dont know if its true or not, I always wanted to know how or why?? Since as someone else put it, the gfci senses an imbalance in current between the hot and neutral. I can see one gfci tripping before the other, (since one may be 'closer' to the imbalance than the other').

I also always said to others, if you were installing receptacles why wouldnt you just 'down stream' one from the load side of the first gfci??

Also like someone said about contractors using portable gfcis and the hair dryers in the bathrooms. Besides the way were headed in the code anyways, I think someday most receptacles in the public domain will be gfci anyway.

 

[paac]

My neighbor installed a GFCI in his garage and couldn't figure out why it wouldn't work. He couldn't understand why the breaker wasn't tripped, but he had no power at the GFCI. Turns out that he had installed it on a circuit that already had a GFCI protected outlet that was "hiding" behind a workbench that was tripped (the GFCI, not the workbench).

Oh, the reason the first one was tripped was that he had the hot and ground shorted together on the second. I guess it worked!:grin: Also explains the breaker not tripping.