GFCI Failures + Gadgets

[Jim Thompson]

Went outside to add another electrical circuit at the BBQ and discovered that all of my nice wire-tagging had faded to non-readable.

So I couldn't figure out which common went with which hot.

Then it dawned on me to simply trip the GFCIs which releases *both* hots and commons so a simple ohm-meter check would do the trick.

NOT! Both GFCIs wouldn't trip when I pressed the test buttons :-(

Went to Radio Shack and bought a Receptacle/GFCI tester for $5.99.

At the same time I noticed a gadget to locate breakers... bought it also ($29.95).

Went home and tested the GFCIs... both have failed :-( Tester was verified on some indoor GFCIs... it would trip them.

Both bad units are outdoors, so maybe it was the heat (they both face the western sun... it gets over 120°F here :-). Any other ideas about why they fail?

The breaker locator is neat... plug a sender unit into an outlet, then scan the breakers... works like a champ.

...Jim Thompson

[w_tom]

Demonstrated is but another reason why homes require a 'whole house' surge protector on each incoming utility wire. GFCIs are electronics that contain effective protection. Protection that can be overwhelmed if incoming transients (ie lightning) are not earthed before entering the building. IOW GFCI failure is a symptom that a whole household of appliances have ineffective protection. Maybe the home does not have the proper central earth ground as well as no 'whole house' protector. But GFCI failures can be created by incoming, common mode transients. I have been told this type of failure damages as many as 50% of all GFCIs in central FL.

$5+ for a GFCI tester? Its noth> Went outside to add another electrical circuit at the BBQ and

[Jim Thompson]

There *is* a whole-house surge-protector. All the GFCIs inside check out OK, so I'm guessing it's a heat issue only.

I earn $5.95 in less than 2 minutes designing ICs. I don't build

*anything* anymore except for fun or if the function is unavailable... plus this tester also verifies phasing and no lost connections ;-)

...Jim Thompson

[Louis Bybee]

Not exactly the same. As I understand it the internal GFCI test switch will work without a ground conductor connected because the connection is effected between the hot conductor after the GFCI Device, and the Neutral before the GFCI. The aftermarket testors wont trip the GFCI Device without a ground conductor connected to it.

There are also usually indicators that allow some level of troubleshooting as to the proper wiring of a receptacle.

Louis--

********************************************* Remove the two fish in address to respond

[w_tom]

Just because some GFCIs are working does not mean a surge could not exist. These GFCIs are outside. Using buried wire? IOW if the exterior (exterior) GFCI made a better earth ground than the central earth ground for 'whole house' protector, then surge would also use GFCI as a destructive path to earth. If mounted on side of building, then this scenario is not so likely.

Operating temperature for older versions GFCI chips is typically up to 70 degrees C. Chip consumes near zero watts. IOW heat is not a likely reason for failure for those type. Have not seen datasheets for newer type GFCIs. But then is that receptacle getting so warm that IC would exceed 70 degree C?

How good (and short) that that ground for the 'whole house' protector. Is there any good earth> There *is* a whole-house surge-protector. All the GFCIs inside check

[Gary Tait]

It will, the test button on a GFCI usually, through a resistor, connects the GFCI protected hot to the unprotected neutral.

[BinaryBillTheSailor]

In direct sun during hot weather? That wouldn't be surprising at all.

BB

[N. Thornton]

Little surge protectors offer very little protection against lightning. That is a common misconception.

indeed.

Regards, NT

[James Meyer]

On Sat, 15 Nov 2003 15:44:40 -0700, Jim Thompson wroth:

Are there both indoor and outdoor grade GFCI breakers available like there are for ordinary receptacles?

Jim

[Jeff]

Rip one apart and see what failed. They usually have screws on the back. All they are is a current transformer with both the hot and the neutral going through it. If the current in the neutral and the hot is not exactly the same, a current is produced in the current transformer. Most GFI's trip at a

5 mA differential, meaning a 5 or more mA current leakage from the neutral or hot will trip the GFI. Perhaps the solder joints failed from the excess thermal cycling?

[Louis Bybee]

If you read my answer above, this is exactly what I indicated. In the second part of my reply I suggested that an aftermarket tester (not the one on the GFCI) wouldn't trip a GFCI where there wasn't a ground conductor connected to it (try it).

Louis--

********************************************* Remove the two fish in address to respond

troubleshooting

[Gary Tait]

If you are asking about a breaker that fits in your panel, just about all current styles have a GFCI breaker.

[James Meyer]

On Sun, 16 Nov 2003 02:10:40 -0500, Gary Tait wroth:

No. I was asking about the outlet receptacle type of GFCI.

But adding a single ground fault breaker per circuit to the panel would seem to be a much better solution than adding multiple outlet type ground fault breakers.

Jim

[Fred Abse]

That's just the same as loading the circuit, it won't work. GFCIs monitor current in *both* hot and neutral, which should be the same.

You need to create an imbalance current by introducing a resistance between hot and *ground* 5mA might do it. 30mA _must_ do it, or the protection is no damn good.

[JeffM]

That sounded too high, so I googled for confirmation. You're right.

When I worked in the hospital, I remember the Electrical Safety Officer coming around with his cart and checking every 110Vac gizmo. His spec was 15uA. (You would marvel at this collection of cut-off molded 110V plugs.)

[Jeff]

Whoa! 15uA - Some insulation will collectively leak that at 120V AC especially on a humid day, and then there's stray capacitance leaking to ground!

[Jeff]

Breakers are the best, however they generally cost 4 to 8 times as much, and have the inconvenience of needing to go to the panel every time they trip (and they can trip often when using power outside). The GFI plugs also have terminals to wire additional plugs, lights, etc to protect things later on in the circuit.

[Mark Jones]

In news:2yZtb.26920$ [e-mail] (Jeff):

Yeah but, in the desert southwest, there ain't much in the way of stray humidity...

[ehsjr]

Why are breakers the best?

[ehsjr]

A GFCI receptacle protects both itself and the circuit connected to the load side of the receptacle.