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Sounds like US regulations are a bit less restrictive than most European ones that I'm aware of. Here you're typically required to measure trip time at nominal trip current and preferably also trip current. The only way to do this in the setup discussed here would be an auxiliary earth, e.g. from an extension lead plugged into a nearby earthed socket or even a long wire connected to the main earth.
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Joined: Apr 2002
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I also have a Hubbell GFT-2G. It sits in my desk drawer.
Inspectors use the 'bug eye' cube tester, polarity & GFI trip test.
If the Hubbell had polarity indication, it would be in the cars.
IMHO, following the UL standard detailed above, still requires polarity confirmation.
John
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You could also test the GFI by going to a nearby Neutral, but you could end up with 2 tripped GFIs instead of 1. That could be the case if the N was from a receptacle downstream of another GFI and lacking one of those little stickers.
Joe
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My question is this. If the house is an old 2 wire system with no ground, and if you install GFCI's, will the personnel be protected against electrocution? Example: if a microwave is plugged into a GFI that has no ground and the hot conductor goes to ground on the microwave frame, and the person is touching the cold water faucet in the sink and the frame of the microwave at the same time, will the GFCI trip? in time? I don't think so. So what's the theory behind replacing 2 wire plugs with gfi's? I have an old house that is wired with 2-wire system inside but the service is fairly new and grounded. How can I make the circuits inside the house safe? would GFI breakers work?
Last edited by billy6139; 10/15/13 07:49 PM.
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Billy3169
A 'basic' explanation of the internal operation of a GFI device is:
The current on the black (hot) and white (neutral) are monitored and compared. Any difference between the current on hot & neutral that exceeds the threshold of the device will 'open' the circuit.
Based on the above, the EGC is NOT required for designed function of a GFI.
The discussion is this thread is reflective of the use of various GFI testers, which require a functional EGC to operate & trip the GFI.
Hope this clears this up.
Last edited by HotLine1; 10/15/13 08:59 PM.
John
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OK, thanks John. I'm kinda new to this website, guess I will have to open a new thread to find out if this will work on a gfci 2 pole main breaker.
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Joined: Apr 2002
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Billy6139:
OK WELCOME to ECN forums!!
THe theory on GFIs is the same, monitoring for any unbalance.
Go ahead, start a thread, and let's see what happens.
John
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Billy,
If you find a path to ground, then there will be less current returning and the GFI should trip. If you can't find a path, no completed ckt, no worries. If you find a path to ground but the source is somehow isolated, no ckt, no trip, and its time to troubleshoot the missing ground reference.
Welcome!
Joe
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Thanks Joe, can't figure out how to start a new thread. I have a 2 unit apt building. All inside wiring is ungrounded 2 wire system. 2 meters and mains outside, fairly new and grounded. 1 unit has 2-50A 2p breakers feeding a sub panel, all screw-in fuses and a range. If I replace the 50A 2p with a 50a 2p GFI Breaker feeding the sub panel, will it protect the circuits inside or will I have to install gfi outlets or outlet with feed thru capabilities if I can figure out the wiring inside. Any help would be much appreciated.
Last edited by billy6139; 10/16/13 12:14 AM.
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Billy,
I think that we should hold to a philosophy of trying to protect people (and animals) from shock without making whole buildings go dark. I would rather get a zap from 120, than fall down the stairs when the light goes out. Protect your loads where necessary. Ask yourself if there are cases where removing power creates risk.
Joe
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