Three phase residential supply

[Bob Ozbirn]

Two legs of a three phase system have been tapped to supply the electrical panel. The other three phase tap supplies the heat pump which only taps two of the lines at the service panel. No transformers are used. I have little experience with three phase systems since I don't do heavy commercial. What is the proper way to do this or is this allowable?



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[Jerry Peck]

The main thing I see it the multiple tapping of the terminals on the load side of the service disconnect - those terminals are likely rated for one conductor only, and, if rated for two conductors (that would be shown on the terminals and/or on the labeling) the conductors would be the same size, and the conductors are different sizes.

Looks like three conductors in the grounding terminal?

Other multiple tapping issues present too.

[Bill Kriegh]

I don't see a neutral on the supply side. All I see is a neutral that starts at the grounding lug and uses the bare grounds to establish the neutral connection to the panel.

~~~UNLESS the solid copper wire going up the conduit is an acceptably sized reduced size neutral for the service conductors. Not likely from what I see here. I gotta dig a bit to see if that was even permitted "back in the day".

[Brad Rodgers]

Not sure if those lugs on the load side of the service disconnect are rated for 2 wires or not but it looks to me like copper and aluminum are mixed on those lugs.