Generator bonding and floating neutral

[sparkness]

Got a 50KW single phase generator we put it in an enclosed trailer. The use of this generator has 2 purposes. 1. power up small marina during storms. 2. Use as a portable generator. Will be stored off site.

The generator will plug into the buildings transfer switch via a pin and sleeve connector and will be a floating neutral. Inside the trailer we have a a small breaker panel. when used as a stand alone in the field we now need to bond. My thought was to use a switch to bond when used for this purpose and post clear instructions for use. any thoughts on this setup?

 

[AA/FC]

That sounds like a decent idea to me.... but I'm not a licensed electrician. When using a generator for different purposes (or different applications) it would be nice to go from a floating neutral to a bonded neutral (or vice-versa ) at the flip of a switch.

 

[sparkness]

I may use a cam switch

 

[Chilliwack Murray]

Neutral bonding is always a case by case basis (and often overlooked with temporary generators).

You need to ensure the switch you are using can carry the full fault current of the generator ie somewhere around 10x the rated current long enough to trip the main breaker on the generator. For this reason, even on rental generators a sliding bar or removable bus bar section is typically used. I’ve seen a (very) large breaker style contactor used but never a switch as it has no withstand rating.

 

[walta]

This sound like a commercial enterprise and no place for amateurs when you are mixing electricity water and the lives of others for profit.

I think the smart move would be to make the generator stationary and hard wire it to a transfer switch so there is zero chance for it to be miss connected in any way.





Walta

 

[wyliesdiesels]

Got a 50KW single phase generator we put it in an enclosed trailer. The use of this generator has 2 purposes. 1. power up small marina during storms. 2. Use as a portable generator. Will be stored off site.

The generator will plug into the buildings transfer switch via a pin and sleeve connector and will be a floating neutral. Inside the trailer we have a a small breaker panel. when used as a stand alone in the field we now need to bond. My thought was to use a switch to bond when used for this purpose and post clear instructions for use. any thoughts on this setup?

so the TS is NOT switching the neutral?

 

[sparkness]

so the TS is NOT switching the neutral?

the TS does not switch the neutral, it is a 2 pole wired to a small old 20k. space at this location is tight and that is why the trailer genset will be used and stored at another location

 

[dave*99]

Inside the trailer we have a a small breaker panel.

Are ground and neutral bonded in this panel?

 

[wyliesdiesels]

Are ground and neutral bonded in this panel?

another good question

 

[sparkness]

When using this generator in stand alone, then this panel must be bonded but not when connected to the building.

 

[wyliesdiesels]

When using this generator in stand alone, then this panel must be bonded but not when connected to the building.

correct. standalone needs bond for short circuit and ground fault pathway to allow breakers to trip. when connected to building electrical system without a switched neutral, needs to be isolated as you dont want neutral bonded in 2 places

 

[mark-NJ]

^^^ This.

It's either a separately derived system or it isn't.