how many ma should a ground fault breaker trip at?

[travish]

Good friend has a house down at the beach, complained of the gfci breaker occasionally tripping. breaker feed 3 outside recepticles. So I drive down and check and the salt water/air has had good sucess rusting out the screws and yokes of the recpticles. I cut the wire on all 3 recpt and replace the recpt and the PVC boxes and covers (screws in yoke broke off or so rusty could not turn them). Total circuit length had to be less than 100' of 12 awg romex. After I replaced i took my hypot and checked with test parameters of 200vac 3 seconds, with a trip of 5ma ( could not remember what a breaker would trip at. hypot showed .53 - .59 ma leakage from hot to neut/neut to grd/ hot to grd.

1) what should the breaker trip at
2) should I be concerned about the quality of the wire with this amount of leakage

I know .5ma is a very small amount but it was only 200volts. I would have thought there would be no leakage at this voltage level.

Never used a hypot to test a recpt circuit, have used it alot at work checking parts we manufacture.

Travis

 

[don_resqcapt19]

A GFCI must not trip at less than 4 mA and must trip at 6mA, so anything above 4mA may cause the device to trip and anything above 6mA must cause the device to trip.

 

[travish]

thanks Don,

I wish I had checked the leakage amount before I changed the recpticles

Travis

 

[ramsy]

2) should I be concerned about the quality of the wire with this amount of leakage
I know .5ma is a very small amount but it was only 200volts. I would have thought there would be no leakage at this voltage level.
Never used a hypot to test a recpt circuit, have used it alot at work checking parts we manufacture.

Never seen a Hi-Pot used on building wire before, much less a current leakage value.
Could 0.5ma be I?R heat loss measured on circuit length?
Typical insulation testers or Megger's give values in Ohms.

 

[weressl]

Good friend has a house down at the beach, complained of the gfci breaker occasionally tripping. breaker feed 3 outside recepticles. So I drive down and check and the salt water/air has had good sucess rusting out the screws and yokes of the recpticles. I cut the wire on all 3 recpt and replace the recpt and the PVC boxes and covers (screws in yoke broke off or so rusty could not turn them). Total circuit length had to be less than 100' of 12 awg romex. After I replaced i took my hypot and checked with test parameters of 200vac 3 seconds, with a trip of 5ma ( could not remember what a breaker would trip at. hypot showed .53 - .59 ma leakage from hot to neut/neut to grd/ hot to grd.

1) what should the breaker trip at
2) should I be concerned about the quality of the wire with this amount of leakage

I know .5ma is a very small amount but it was only 200volts. I would have thought there would be no leakage at this voltage level.

Never used a hypot to test a recpt circuit, have used it alot at work checking parts we manufacture.

Travis

Common polymers used as wire insulators do absorb moisture over time. It is especially true with PVC based insulation in salt water. (PVChloride and Salt/Chloride like each other) Consequently your leakeage value increases over time. To remedy this, replace the GF breaker with a regular breaker with an ordinary one and install a GFCI receptacle in place the first recepticle in the chain and tag the subsequent ones with GF Protected labels. This will only work if the lead to the first rec consist the majority of the run that is subject to the water/salt exposure. Otherwise replace all recepticles with GF ones.

 

[travish]

Rodger, I have never used the hypot in this application before, I had no other method of trying to check if the circuit conductors were ok or not. My understanding of how the hypot works is that the unit sends out the amont of voltage that you set and it measures the current flow, if the measure is less than the preset level I get a pass condition, if it is greater then I get a fail. Some of the Engineers maybe can correct me if this is not the way that a hypot works. If the breaker was good and circuit conductors were draining current in the level of 5ma or so I did not think I could accuratly measure that level with my meter. I had nothing plugged into any of the recpticels and I removed the wires from the breaker and put the hypot on the circuit, checking from black to grd & neut, then from the neut to grd & Black. then from black to the panel box case then neut to the panel case. at any rate all of the readings were very similar.

Travis

 

[weressl]

Good friend has a house down at the beach, complained of the gfci breaker occasionally tripping. breaker feed 3 outside recepticles. So I drive down and check and the salt water/air has had good sucess rusting out the screws and yokes of the recpticles. I cut the wire on all 3 recpt and replace the recpt and the PVC boxes and covers (screws in yoke broke off or so rusty could not turn them). Total circuit length had to be less than 100' of 12 awg romex. After I replaced i took my hypot and checked with test parameters of 200vac 3 seconds, with a trip of 5ma ( could not remember what a breaker would trip at. hypot showed .53 - .59 ma leakage from hot to neut/neut to grd/ hot to grd.

1) what should the breaker trip at
2) should I be concerned about the quality of the wire with this amount of leakage

I know .5ma is a very small amount but it was only 200volts. I would have thought there would be no leakage at this voltage level.

Never used a hypot to test a recpt circuit, have used it alot at work checking parts we manufacture.

Travis

The voltage is too high to give you an accurate test data. The trip leakage of 4mA is at 115VAC, not at 200VAC. The approximate leakage would be around 3.39mA at nominal circuit voltage. It is fairly close and if the moisture/humidity content changes a nuisance trip may be experienced.

 

[ramsy]

Rodger, I have never used the hypot in this application before,

Hipot leakage data is typically not available on most Insulation testers, nor from wire manufactures, neither do leakage to length charts appear on GFCI device listings, nor perhaps without subscription to published engineering authorities. It may be a worthy student thesis of graduate/post secondary engineering, if made available to the public domain.

In the mean time, Laszlo brings his engineering expertise to answer our questions.

My previous experience with HiPot testing was diagnostic auto-chemistry instrumentation to 10kV, not applicable to insulation types used in building wiring.

I've seen 4-6mA GFCI's work fine on 115v building wiring tested @ 2.8MΩ N-G, using the 100v setting of an AVO MEGGER BM80/2 insulation tester.

If my use of Ohms law is correct, theoretically, GFCI's may hold on branch circuits tested near 300KΩ before reaching a 4mA trip point.