GFCI Risks? Update

DrewE wrote:

keepingthelightson wrote:
IF you are connecting the shore power cord to a GFCI outlet on your house and you are expecting the GFCI in your trailer to work. IT will not. You CAN NOT have two GFCI on the same circuit in parallel. You need to remove your GFCI from your shore power at the house.

Good luck! ;)

35 yrs. electrical experience.

That makes absolutely no sense to me. A GFCI works by measuring the current difference between the hot and neutral legs, and tripping if it exceeds some tiny threshold. (The sense of the current is, of course, opposite—hence it's okay so long as the current flowing through the hot all returns via the neutral).

You can't have a GFCI wired such that there's a neutral return path separate from the GFCI, whether it's through another GFCI or not, but that's a different matter entirely. Connecting one GFCI to the load terminals of another is not problematic and indeed happens quite frequently—air dryers, for instance, have GFCI's built into their cord sets (required since 1991), and are commonly plugged into GFCI-protected outlets in bathrooms.

Edit: I guess apparently hair dryers may have immersion detectors rather than GFCIs in their cordsets, which is not quite the same technology, but the basic electrical facts remain.

"Immersion" detector IS the same as a GFCI except for the fact that an immersion detector is a "one and done" non resettable version of a interrupter.

Initial function is the same between both but the idea behind the Immersion version is to prevent you from operating a device that may have been immersed in water ever again to protect you from your own bad judgement (I would have never thought to plug in anything that was dunked in water without inspecting the inside for damage)..

Immersion detector

IMMERSION DETECTOR FAQS

Conair® manufactures its hair dryers with two different kinds of safety plugs. The ALCI is known as an Appliance Leakage Current Interrupter. This unit has the Reset button and the Test button. The circuit is looking for leakage of current between the two conductors. This unit sometimes trips when lights are turned on and off, when the dryer is plugged in, or when a new dryer is taken out of the box and plugged in by the consumer who doesn’t know how to operate the Reset feature. An IDCI refers to Immersion Detector Current Interrupter. This unit trips only when the dryer has been immersed in water. The dryer should never be used again after immersion because of the potential dangers a water-damaged unit presents to consumers. That is why this unit trips once and is not resettable - because it shouldn’t be used again! Both safety plugs look a little different but they provide the same function - they protect the consumer from electric shock.

IMMERSION DETECTOR PATENT INFO

When a small current passes between the sensing conductor and the ungrounded or grounded neutral sides of the line or earth ground, current is shunted through the detection circuit from the ungrounded to the grounded neutral conductor, and away from the appliance circuit. A fuse link is opened in one side of the line which, in turn, releases normally open contacts, in the other side of the line, which open and remain open, so that both sides are permanently interrupted.


As far as "multiple" GFCIs in the same circuit, it won't harm anything although not really a recommended thing to do since it may increase the chances of false trips on one or all the GFCIs..

Multiple GFCIs are done every day, look at wall A/C units, everyone that runs on 120V HAS a GFCI on it.. You CAN plug it into an outlet protected by a GFCI outlet or circuit breaker upstream and it will work.