Re: Owner gettig shocked
What has happened is the trailer should have a equipment grounding conductor ran with the feeders to the grounding bar in the panel inside the trailer. if there is one then it has lost connection or the grounding and neutral is not bonded back at the service point. or if there is not one installed then one needs to be ran.
What happens is the panel inside the trailer has to have the grounding kept separate from the neutrals. if there is no grounding path back to the source and a appliance shorts to the trailer grounding then it can't cause a breaker or fuse to open as the path (neutral) back to source resistance is too high or non existent, this will bring all the grounding on this trailer up the the potential of the hot. Even with a ground rod at the trailer bonded to the frame will not trip a breaker as a ground rod will only provide about 4.8 amps of current path, as you can see this wont trip a 5 amp breaker let alone a 15 amp. Now the NEC requires 4 insulated conductors ran with the feeders from the service to the trailer if the service disconnect is located father than 30' from the trailed an additional disconnect is required to be placed no closer than 2' from the trailer and not more than 30' this disconnect is require to be kept above 2' from the grade level. Now if you have to install a disconnect you can use the exception to run 3 conductors to this disconnect and bond the grounding to the neutrals at this point but from this disconnect to the trailer panel there must be 4 insulated conductors and grounding and neutrals must be kept separate. A ground rod is required at this disconnect and at the trailer also.
If you put a meter between the ground bar and the neutral bar you might see 120 volts this is because there is a shorted hot on a branch circuit, and since there is no return path (neutral) for this current it will just bring the grounding up to 120 volts. turning off each breaker will show you which one it is (Hot water heater or electric dryer is the two most causes for this)
But I must stress that this trailer's wiring must be corrected ASAP!!!
Over the years I have seen this many time when trailer installers do the electric hook up and don't run the required separate grounding conductor, instead they will use a ground rod thinking it will allow the breaker to trip. A very bad mistake as you can see what happens.
Remember this grounding conductor must be insulated.
[ November 10, 2004, 07:48 PM: Message edited by: hurk27 ]
