On Mon, 6 Jun 2005 21:40:10 +0200 TexasFlood wrote: | I am to build an electrical panel for a mobile unit which is to be powered | by 110VAC / 60 Hz (1 phase, 1 neutral and ground). | The unit is equipped with medium heating elements and have a max. current of | 20A which is connected through a Hubble connector. | | To protect from ground fault I wish to build the panel with a ground fault | breaker included. | | According to European rules both the phase and the neutral have to be | disconnected in case of a ground fault. | Also the trig limit for protecting personell is 30mA current. | | - What Ground Fault Breaker should I use. I would prefer one from Allen | Bradley but can't seem to find one that | disconnects the neutral line also. | - Is it mandatory that the neutral have to be diconnected also according to | US rules ?
US rules do not require disconnection of the neutral. IMHO, they should, but in actual fact they don't. Typical GFCI breakers do not have this capability, but most GFCI receptacles these days do.
The cheapest solution would be to use a 20-amp rated GFCI receptacle device that does have neutral interruption, and use that in a panel. You can wire your load to the "load" terminals. There are such devices made with no outlets, called "dead front".
Since your case involves only one phase wire, you could do this with a
2-pole GFCI breaker. One of the phase inputs will power the circuitry inside, and you'll have to figure out which one. Then wire the other to neutral. Load will be connected to the breaker terminals as usual, and the white pigtail wire will be connected to the neutral bus (not to the neutral terminal on the breaker). You would not want to do this in a distribution panel, just in a single circuit panel.
Another more expensive option, which I am looking at to deal with 2-pole circuits where I want the neutral interrupted, is to follow a GFCI breaker (that doesn't interrupt neutral) with a contactor that interrupts all conductors together.
| - Also as far as I know US rules say that the trig limit for protecting | personell have to be 5mA - is this true ?
Somewhere between 2mA and 6mA, with 5mA being the preferred level.