3 phase panelboard as single phase

[Nium]

I apologize if this topic has already been covered. I have searched the forums in an attempt to discover an answer.

Looked through NEC 2008, Article 408 and was unable to find a reason not to use a 3 phase load center for a change to single phase service.

My situation is that customer has a 3 phase service that he doesn't use but has to pay $300+ a month to have attached to the building. There are two other single phase services to the building. I would like to tap into one service to run feeders to the existing 3 phase panels (2 panels, 1 is Wye setup off transformer, the other panel is delta off 2nd transformer with no neutral on delta panel) I'm going to eliminate the transformers and wire the feeders directly to the 3 phase main breakers for each panel and run a neutral to the panel without one (currently). I realize that I'll be losing a third of the breaker spaces this way but the customer only has minimal loads (ie. fluorescent 8' luminaire, high bays, heater motors, receptacles) so the lose of breaker spaces isn't an issue.

I would like to know if somewhere else in the code it isn't allowed for a labeled 3 phase panel to be used as a single phase and if using the 3 phase main breaker as a single phase breaker would just be a bad idea.

Since this is my first post let me just say I already know I'm an idiot so no one needs to point it out. :grin: I have my Master Electrician license issued by Allentown, PA.

 

[RUWired]

Nium welcome to the forum i'm just north of you, I've seen this before and it's a pain as the panel gets closer to being loaded.

I think the only problems installing this is the application in which you install the jumper. The terminal of the breaker being tapped has to be identified for two conductors (110.14A). The tapped conductor has to be rated for or better than the amperage of the breaker (240.21B), and the panel must be relabeled as a single phase panel.(408.58)

One could argue that the phase arrangement is not ABC front to back or left to right.(408.3E)
Rick

 

[480sparky]

...............My situation is that customer has a 3 phase service that he doesn't use but has to pay $300+ a month to have attached to the building. ...........

He gets charged $300 a month just to have the wires dropped to the structure, even if he doesn't use a kW of power?

 

[Nium]

Thanks for the reply RUWired.

He gets charged $300 a month just to have the wires dropped to the structure, even if he doesn't use a kW of power?

Yes, in addition to having to pay for any kW used there is an additional charge just to have the 3 phase service. I have had another person ask me to do the same thing, convert 3 phase panel to a single phase sub panel, because he didn't want to continue to pay the additional charge too. He had the landlord take care of it so I never went back for that job.