Open Ground question
Hi all, I have been having a problem with plugging into the shore power at our storage facility. They have all circuits run through GFCI outlets on the pole. When we plug in and we are not running any...
Forum Discussion
DrewE wrote:ktmrfs wrote:
open ground will NOT trip a GFI. A GFI is designed to work with a circuit that is not grounded, e.g. the old two prong plug.
there are TWO things that will cause a GFI to trip.
1) unbalanced current between the hot and neutral.
2) ground neutral short. e.g. somewhere downstream the ground and neutral are touching.
now a regular 30A RV circuit most often does NOT have a GFI, so no issue.
couple of things that could be causing an issue.
1) leakage in the fridge 120V element to ground.
one way to check is to turn OFF every breaker in the RV. GFI should Not trip. if it does, the fault is before the 30A main breaker. If no GFI trip, trip each circuit and see which one trips the GFI. whatever circuit trips the GFI tells you which circuit either has excessive leakage current or a ground neutral short.
This is one of the best responses to the question; there are a lot of confused people who seem not to understand what a GFCI detects and what it does not detect.
If you have leakage from hot to ground, shutting off the breakers will help track that down. If there's a short or partial short between neutral and ground, shutting off the breakers will not take that away (they only shut off the hot side) and you're left with the job of hunting it down. These can be rather tricky to find, either in a house or in an RV, but it's a definite safety hazard under certain fault conditions such as an open ground connection and should be corrected.
There is also a small chance that there is sufficient leakage from ordinary noise suppression and other input conditioning circuits on the various electrical devices in the RV which, if taken individually, would not be sufficient to trip the GFCI. This would only affect things with three prong plugs. In most cases it's more productive to assume that this is not the cause and look for other problems.
I suggest you read the two posts that I have quoted and at the first opportunity follow the suggestions given in the first quoted post.
This problem seems to come up once or twice a year and is usually a common touching a ground or a ground common reversal.
