GFCI's with nonmetalic plumbing

[jasondienethal]

How can a GFCI work with nonmetalic plumbing? I have a GFCI outlet that will trip from phase to ground, but it will not trip if i go from the faucet to groung, or the metal sink to ground. The supply pipes are metal, bu the riser from the valve to the faucet is PVC, as are the drains. Will the GFCI work properly if you drop the apliance in a sink full of water?

 

[George Stolz]

It won't trip the GFCI all by itself, but as soon as someone reaches in to grab it, their low resistance path to the earth will present the GFCI with what it needs to trip.

It may hurt, but it won't be lethal. It's why GFCIs are designed to the 5mA threshold. It's survivable.

Edit: Whoa - the supply pipes are metal and it doesn't trip, and it's a metal sink?

 

[kwired]

It won't trip the GFCI all by itself, but as soon as someone reaches in to grab it, their low resistance path to the earth will present the GFCI with what it needs to trip.

It may hurt, but it won't be lethal. It's why GFCIs are designed to the 5mA threshold. It's survivable.

Edit: Whoa - the supply pipes are metal and it doesn't trip, and it's a metal sink?

he said:

The supply pipes are metal, bu the riser from the valve to the faucet is PVC

jasondienethal:

A GFCI does not care what is grounded and what is not. It only cares that the current that leaves on one current carrying conductor returns on another current carrying conductor (with typical GFCI receptacle this would be the hot and neutral conductors) with a 2 pole GFCI breaker it would mean both hots and neutral. If your sink is inherently not grounded you actually have less risk of shock but the GFCI will still protect you if a low enough impedance should occur to allow a potential shock.

 

[LarryFine]

Will the GFCI work properly if you drop the apliance in a sink full of water?

If the GFCI doesn't trip, it's because the plastic piping doesn't conduct well enough for that contact to be a hazard.

GFCI devices are necessary because we have grounded systems, and only work because we have grounded systems.

 

[don_resqcapt19]

There can be a shock hazard within the water where there is not a path that will cause the GFCI to trip. There will a voltage gradient in the water that can be a hazard to someone in the water. Just reaching you hand in would problably not be a problem, but being in a bathtub with an energized two wire device could be an issue. This issue is the very reason that Article 680 requires us to bond the pool water.

 

[kwired]

There can be a shock hazard within the water where there is not a path that will cause the GFCI to trip. There will a voltage gradient in the water that can be a hazard to someone in the water. Just reaching you hand in would problably not be a problem, but being in a bathtub with an energized two wire device could be an issue. This issue is the very reason that Article 680 requires us to bond the pool water.

Say you have a tub that is by nature an insulator and have no conductive paths that are attached to it. Now place an energized two wire device in the water at one end. GFCI should not trip - any current leaving one conductor returns on the other GFCI senses no imbalance. Wouldn't voltage gradient in the water rapidly decrease the farther away from that immersed device you get? The only current flow through water will be within the immersed device. Place another energized device on opposite end of tub or even just any grounded object, and now you will have current traveling across the tub - GFCI should trip in this case.