High leg on three phase panelboard?

[X49]

I have a dry type transformer in 480V-240V Delta / 120V center tap configuration and I'd like to connect it to a 3-phase panelboard. All loads are 240V single phase but only a couple require a neutral.

I know this would work if the loads were connected to the proper phases, but I'm worried about the 208V B-phase high leg and the possibility of somebody trying to connect a 120V single phase load to it in the future. Is there any way to safely use a three phase panel? Are there any code restrictions to doing this?

Thanks

 

[dpc]

This is covered in the NEC. See 110.15. High-leg must be permanently marked and labeled.

Next time, use a 208/120V system. It makes everyone's life easier, and safer.

 

[X49]

Thanks dpc. In this case I had existing 240V equipment, but next time I'll definitely limit the 240V distribution to single phase.

I've seen NEC 110.15 and also CEC 4-036 (5) (Canadian electrical code, which is what I must follow).

The CEC article states: "... the grounded conductor... shall be located in a compartment provided for single-phase connections and the phase conductor having higher voltage-to-ground shall be suitably barriered from that compartment."

Not sure how many Canadians are on this board, but has anybody seen a panelboard like this or modified an existing panel to meet this requirement?

 

[resqcapt19]

I have not seen the Canadian panel, but I have seen custom assembled panels where they did not install the high leg bus fingers in part of the panel. They installed all 3 bus fingers where the three phase breakers were installed, but only provided the A and C phase fingers in the rest of the panel. Unless someone removed a 3 phase breaker there was no danger of connecting a 120 volt load to the high leg.

 

[waross]

The four wire delta is very rare in Canada. There are exceptions in rural areas, but industrial engineers and electricians may never in their career encounter a four wire delta system in Canada.
I would talk to your local AHJ and your local electrical supplier. The local utility may be able to offer suggestions.
You may be able to meet the code rule by installing a four wire splitter and running a three wire panel without neutral for your 240 volt loads and a single phase panel for your 120 volt loads.
Please let us know the final solution.
Thanks.

Bill
--------------------
"Why not the best?"
Jimmy Carter