ECN Forum Forums General Topics of the Trade General Discussion Area 2 phase services

This topic has probably been brought up here before, but through some searching I found nothing. (Sorry if I'm beating a dead horse )

My question is, has anyone worked in a building that had 2 phase power? Was it POCO supplied, if so, could you explain the transformer hookup? (If overhead) What kind of disconnects / panelboards where used? I seen a few pictures of a smaller 2 phase service on a home inspector site. I consisted of 2 FPE panelboards, both feed with 2 hots and shared a nuetral. The meter said 2 phase, 5 wire. It had 5 wires for a utility drop. (Pics didn't show transformer hookup)

Just wondering if anyone had any information or examples on what a service consisted of. I know this is pretty much an obsolete system, but may well still exist in larger cities so it would be interesting to know how modern components, panelboards, etc are connected. I have seen diagrams and schematics for a Scott-T connection, and the theoretical aspects of changing 3 phase to 2 phase make sense, I was more or less wondering about the physical aspects.

Thanks everyone for any tidbits you can provide.

I have seen diagrams in literature from Cooper Power Systems and in Ugly's book.

The common conductor needs to be sized very carefully. On a standard 2-phase 3-wire circuit the common conductor needs to be 1.414x the line conductors.

The meter 2 phase 5 wire has the following terminals.

Phase 1 line
Phase 1 load
Phase 2 line
Phase 2 load
Neutral

so 5 wires are used.

A 2-phase 5-wire system is basically (2) 3-wire systems, loads were never connected between Phase 1 and Phase 2.