Possible hazard in a mobile home

[duck_huntr85]

hey all,
i was working at a trailer park, switching the overhead to underground and the pole mounted meter sockets to meter peds with main breakers in them. the last service i changed over had to have the wiring changed because it was only a three wire system. i changed it to a 4 wire and removed the bonding jumper between the neutral bar and the grounding bar. It was at this time that i noticed a 6-2 nm wire. this is what was used to feed the electric stove. it had a digital clock so i know this stove needs a neutral so it can have a 120 V circuit to run the clock. But all it has is the 2 hot legs and the 10 awg ground wire. i wasn't there when the utility switched the meters over to the pedestals but the owner of that trailer called me to tell me that everything was fine and even the clock on the stove was working. i know this is wrong since the only place the grounding conductor is connected to the neutral was all the way back at the pedestal, since the two are separated at the panel in the trailer. i know it must be changed, and it will be, but was wondering what are the possible problems caused by such a connection.

 

[ceb58]

hey all,
i was working at a trailer park, switching the overhead to underground and the pole mounted meter sockets to meter peds with main breakers in them. the last service i changed over had to have the wiring changed because it was only a three wire system. i changed it to a 4 wire and removed the bonding jumper between the neutral bar and the grounding bar. It was at this time that i noticed a 6-2 nm wire. this is what was used to feed the electric stove. it had a digital clock so i know this stove needs a neutral so it can have a 120 V circuit to run the clock. But all it has is the 2 hot legs and the 10 awg ground wire. i wasn't there when the utility switched the meters over to the pedestals but the owner of that trailer called me to tell me that everything was fine and even the clock on the stove was working. i know this is wrong since the only place the grounding conductor is connected to the neutral was all the way back at the pedestal, since the two are separated at the panel in the trailer. i know it must be changed, and it will be, but was wondering what are the possible problems caused by such a connection.

If I am understanding what you have done you separated the neutral and ground at the main breaker? Do these pedestals have branch circuit breakers in them? Where is the GEC bonded to the neutral? Where dose the circuit for the stove originate from?

 

[duck_huntr85]

The neutral is bonded to the gec at the pedestal, the pedestal only has the 100 amp breaker that supplies the trailer panel. the stove circuit originates from the panel inside the trailer

 

[ceb58]

The neutral is bonded to the gec at the pedestal, the pedestal only has the 100 amp breaker that supplies the trailer panel. the stove circuit originates from the panel inside the trailer

At the pedestal your neutral and EGC should be bonded together. They will not separate until the trailer panel. As far as the stove if the trailer was set up before the 05 code, I think, then 3 wire was OK for the stove and dryer. And I will assume the wiring from panel to stove is original to the trailer and if so it was inspected and passed at the time of mfg.

 

[duck_huntr85]

the neutral and egc are bonded at the pedestal and seperate at the trailer panel, i thought i had said that but i guess not. the wire feeding the stove is not original and i can tell that simply by how it is ran. it was obvious some fly-by-night put it in. it may have been legal when 3 wire systems were legal but the panel is now a four wire system, which i believe is an older code requirement than just to 05', at least for mobile home services. now that the neutral and grounding conductors are separate, i figured this wire may cause some sort of threat. its a 6-2 nm cable with a 10 gauge ground wire. the 10 gauge ground wire has been brought to the grounding bar in the panel inside the trailer. which means if the stove has a bonded neutral, the 10 gauge ground wire is being used as the neutral, but that wire isn't in direct contact with the neutral bar in the trailer panel, its connected to the grounding bar in the trailer panel. that 10 gauge ground wire is getting its connection to the neutral all the way back at the pedestal, not at the panel in the trailer. am i making sense? im sorry if im talkin in circles here but it doesnt seem safe.

 

[readydave8]

At the pedestal your neutral and EGC should be bonded together. They will not separate until the trailer panel. As far as the stove if the trailer was set up before the 05 code, I think, then 3 wire was OK for the stove and dryer. And I will assume the wiring from panel to stove is original to the trailer and if so it was inspected and passed at the time of mfg.

To me it sounds more likely that the 6/2 was not original to the trailer and was added later, may have come from the factory with gas stove? We have been required to run 4 conductor to trailer (separate ground and neutral) for as long as I can remember (25-30 years), and mobile home stoves and dryers been 4 conductor for at least this long. My memory isn't always great but I don't remember being allowed 3 conductor to mobile home stove or dryer.

Also I don't think that 6/2 wg was ever legal to stove or dryer, we always had to use 6/3 or entrance cable.

 

[duck_huntr85]

i know its not right to have 6-2 feeding the stove my question is if there is a potential hazard of some sort since they are using the ground wire (which is attached to the grounding bar) as the neutral (which means the current is traveling all the way back to the pedestal to establish that neutral connection)

 

[ptonsparky]

The potential is there, albeit small.

 

[hillbilly1]

i know its not right to have 6-2 feeding the stove my question is if there is a potential hazard of some sort since they are using the ground wire (which is attached to the grounding bar) as the neutral (which means the current is traveling all the way back to the pedestal to establish that neutral connection)

Where the danger comes in, is if for some reason you lost the ground connection, everything that is bonded to it will become "Live" to the service ground, or to the point where the ground was broken. You also will have some current flowing on the ground. At least they just used it for the stove, not the trailer, I dug up a piece of 6-2 nm buried about 6" underground in a trailer park a friend of mine bought. He said the park was a mess electrically, and he was right!

 

[kwired]

At the pedestal your neutral and EGC should be bonded together. They will not separate until the trailer panel. As far as the stove if the trailer was set up before the 05 code, I think, then 3 wire was OK for the stove and dryer. And I will assume the wiring from panel to stove is original to the trailer and if so it was inspected and passed at the time of mfg.

I believe the change that no longer allowed 3 wire circuit to ranges and dryers (in general) was either 1993 or 1996 NEC, but in mobile homes it needed to be 4 wire circuit long before that, possibly always was a requirement in mobile homes.

Where the danger comes in, is if for some reason you lost the ground connection, everything that is bonded to it will become "Live" to the service ground, or to the point where the ground was broken. You also will have some current flowing on the ground. At least they just used it for the stove, not the trailer, I dug up a piece of 6-2 nm buried about 6" underground in a trailer park a friend of mine bought. He said the park was a mess electrically, and he was right!

Bigger concern yet is the metal frame of the trailer that is connected to the equipment grounding conductor, when it becomes energized and you are under the trailer making a repair of some kind, it often results in death to the person involved. Standing on two feet with shoes on is a lot more resistance than laying on the ground when you contact a live conductor.