Electrical Q

[crokett™]

A friend had a house moved to some land he owns and once the subdivision on the land goes through He’ll set the house on a foundation and use it as a rental and future in-laws residence. The electrical panel isn’t labeled. he’s trying to do as much as he can with the electrical and plumbing and going through the systems to save time after the house is put on the foundation. He has an existing powered building on the property . He wired a 110 V extension cord from that building to one of the breakers in the panel so that he can start tracing circuits -checking lights, testing outlets, etc. .That worked until he jumpered that breaker to an adjacent breaker to get both sides is the panel hot. When he did that it started tripping the GFI breaker at the existing building. We’re wondering why. The house that was moved had no meter and no connection to the grid or ground rod, etc. the neutral and ground on the extension cord is connected to the neutral bus of the house panel, the house panel has neutral bonded to ground. I’m thinking that with both sides of the breaker bus powered that results in an imbalance across the neutral/ground.

[Roly]

A friend had a house moved to some land he owns and once the subdivision on the land goes through He’ll set the house on a foundation and use it as a rental and future in-laws residence.  The electrical panel isn’t labeled.  he’s trying to do as much as he can with the electrical and plumbing and going through the systems to save time after the house is put on the foundation.  He has an existing powered building on the property .   He wired a 110 V extension cord from that building to one of the breakers in the panel so that he can start tracing circuits -checking lights, testing outlets, etc.  .That worked until he jumpered that breaker to an adjacent breaker to get both sides is the panel hot.  When he did that it started tripping the GFI breaker at the existing building.  We’re wondering why.  The house that was moved had no meter and no connection to the grid or ground rod, etc.  the neutral and ground on the extension cord is connected to the neutral bus of the house panel,  the house panel has neutral bonded to ground.   I’m thinking that with both sides of the breaker bus powered that results in an imbalance across the neutral/ground.

Try connecting just to where he jumped to and not to the first one and see if it holds ok.   If so it may be too much capacitance between conductors unless something in the moved house is grounded somewhere.    Roly

[Phil Thien]

Has he checked both sides of the panel with a meter?  Just in case something was shorted or something when the house was moved?

[crokett™]

No. I told him to change the way he has it hooked up and redo it so he can switch both sides of the house panel separately. If the other side trips the breaker without the working side being powered then it’s grounded somewhere. I’m wondering if assuming everything is ok with the house wiring why would wiring it the way he did cause the problem.

[Phil Thien]

I'd not assume everything is okay with the wiring.

BUT IF IT WERE, running an extension cord to a panel in another house, seems like a lot to ask of some modern breakers?

[crokett™]

It worked just fine years ago when I was building my shop. I had an extension cord powering the panel in the shop. That gave me
lights and a few outlets to power tools until
I had permanent power. In my friends case there’s no real load. He’s testing lights and has a plug in circuit tester on the outlets

[Phil Thien]

Now I'm curious what he finds as the issue.

[crokett™]

It worked just fine years ago when I was building my shop. I had an extension cord powering the panel in the shop. That gave me
lights and a few outlets to power tools until
I had permanent power. In my friends case there’s no real load. He’s testing lights and has a plug in circuit tester on the outlets

[kencombs]

A friend had a house moved to some land he owns and once the subdivision on the land goes through He’ll set the house on a foundation and use it as a rental and future in-laws residence.  The electrical panel isn’t labeled.  he’s trying to do as much as he can with the electrical and plumbing and going through the systems to save time after the house is put on the foundation.  He has an existing powered building on the property .   He wired a 110 V extension cord from that building to one of the breakers in the panel so that he can start tracing circuits -checking lights, testing outlets, etc.  .That worked until he jumpered that breaker to an adjacent breaker to get both sides is the panel hot.  When he did that it started tripping the GFI breaker at the existing building.  We’re wondering why.  The house that was moved had no meter and no connection to the grid or ground rod, etc.  the neutral and ground on the extension cord is connected to the neutral bus of the house panel,  the house panel has neutral bonded to ground.   I’m thinking that with both sides of the breaker bus powered that results in an imbalance across the neutral/ground.

The GFCI only cares about the current flow on the two conductors of the circuit (black/hot and white/neutral).  Exactly (or nearly exact, the exact spec escapes me a the moment) the same amount must be present on both wires.  Ground is not part of the equation.  My guess is that something fed by on the  breaker bus that was jumpered has a ground fault, leaking some of the current off, causing the trip. 

If it were me, I'd open all the breakers, connect the extension to the main breaker lugs, (or lugs if it main lug panel) then begin closing breakers until it tripped.  Then examine all the wiring, recepts etc fed by the last breaker closed.  A loose wire touching a box, adjacent wire etc could cause that.

[SLandrum]

The temporary feed is a 110VAC connection, which is one hot and one neutral and hopefully one ground. Is the panel in the moved house the usual 220? Normally two hot busses and a neutral? Maybe the temporary connection has the neutral connected to what is usually the other hot bus. So jumpering to an adjacent breaker shorted the hot and neutral?