Changing Residential 3Phase System to single phase but use a phase converter for AC?

J

jim609

Member
Location
Phoenix, AZ
Occupation
Electrical Contractor
I have a client with a 3 phase residential system 120/240 with delta, panel blew off the wall in a storm. Having a heck of a time finding a replacement. My question is, if I just went to a single phase 120/240 volt system could I run the AC on a phase converter and would that have to be a rotary phase converter? Would a much less expensive digital converter work?
 
The 3 phase load centers approved by the local utility are not available any longer. The closest I have found a is a $4000 milbank system which must be approved. Just trying to find a option for the client to get them power back in their home
 
Is the HVAC system still 3 phase? Most modern residential HVAC systems are single phase.

It may be far cheaper (and cheaper long term) to change the HVAC system then to maintain the 3 phase service.

I agree with @ActionDave that it is always best to match supply and load. I wouldn't bother trying to run a residential HVAC system on a phase converter.
 
I agree i would rather not do it, rotary phase converter are great but the digital ones are not so much. That said I am trying to find a way to get them back up and running. It drives me crazy an ac company installed a 3 phase unit.
 
Are you looking for a three phase meter main combo? If not, why would the utility company care about what panels you are using after their meter? Can you get a separate meter enclosure and a separate panel to make it easier to acquire the equipment?
 
jim609 said:
The 3 phase load centers approved by the local utility are not available any longer. The closest I have found a is a $4000 milbank system which must be approved. Just trying to find a option for the client to get them power back in their home
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Why do you need a 3-panel? Install (2) Main breakers, one 1-phase with a panel and the other a separately mounted 3-phase breaker only for the HVAC.

Is your problem the meter base?
 
APS the local provider only has certain manufacturers and set ups approved. It has been a nightmare trying to find it in 3 phase as it is so uncommon anymore. That is why I was looking to just switch to single phase. I can't even source an approved meter can to just install a mlo panel with 2 mains. It has been ridiculous
 
A picture of the panel and meter face would be the only way to help... and getting srp to change the customers voltage would be ridiculously expensive.
Are you sure its not a single phase delta? Very common in certain nieghborhoods still..

At the very least, post exactly what it says for voltage on the meter and a catalog number on the panel...
Plus if it is the old goofy delta leg to the a/c and c.b., they are also buying a new a/c.
 
jim dungar said:
Why do you need a 3-panel? Install (2) Main breakers, one 1-phase with a panel and the other a separately mounted 3-phase breaker only for the HVAC.

Is your problem the meter base?
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I bet he is trying to replace some sort of all in one meter/load center and there isn't any on POCO approved list. If staying with three phase might need separate meter socket and load center.
 
kwired said:
I bet he is trying to replace some sort of all in one meter/load center and there isn't any on POCO approved list. If staying with three phase might need separate meter socket and load center.
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Got to be it, poco has no say in equipment after the meter unless they are supplying it. Our poco got in trouble requiring all meter bases to be Milbank. They found out such a requirement would legally require them to supply the meterbase’s for free, so they dropped that rule.
 
ActionDave said:
I wonder if a delta breaker is an option.
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Not so much a matter of option, but exactly why a pic would be great.

so the old resi panels im thinking of are yes, 4 wire delta but the high leg goes in its own little seperate c.b. main and out to whatever (originally meant for chickie incubators and small scale ag. stuff- then in the 70's, a/c) but only in a very specific neighborhood/srp poco, not west valley aps...
Believe me, a goofy/crazy ul listedsettup if youve ever seen one... thats why a pic of both are needed... plus a delta meter is visibly different than a regular old 3wire 120/240 resi meter- they are very long and have a little light on them.

Parts can be had but at least srp here i know will not green tag used parts if they know something broke.
Problem. Jims solution will work but you are sorta stuck using only what the poco designer nazi's approve.
 
There are 3wire delta panels too, and justas goofy a settup. The high leg only pairs a few spots for a/c, waterheater ect so a h.ownr wont acc. use a high leg for 120v... i need to ask around uf one of my friends have a pic of this crap...
 
ActionDave said:
I wonder if a delta breaker is an option.
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I thought these were prohibited in current code.

A 'delta breaker' as I understand it was a breaker made for a single place bus that had an extra pole and terminals for the third phase. This third phase bypassed the main breaker in the panel.
 
jim609 said:
It drives me crazy an ac company installed a 3 phase unit.
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When did they install this unit, and how large is it?

Is it really a system with an across the line 3 phase compressor (something that requires 3 phase power to function) or a system with single phase loads configured for 3 phase use?
 
ActionDave said:
I wonder if a delta breaker is an option.
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Delta breakers have been prohibited by the NEC for close to 50 years now.
No major breaker manufacturer even makes one anymore.

For the younger people, a Delta breaker was a 3-pole device with special construction. Phases 1 and 2 looked like a standard breaker, which plugged onto the panel bus, while Phase 3 had an incoming line lug and an outgoing load lug, it had no bus connection at all.
 
jim dungar said:
Delta breakers have been prohibited by the NEC for close to 50 years now.
No major breaker manufacturer even makes one anymore.

For the younger people, a Delta breaker was a 3-pole device with special construction. Phases 1 and 2 looked like a standard breaker, which plugged onto the panel bus, while Phase 3 had an incoming line lug and an outgoing load lug, it had no bus connection at all.
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Not young by any standard, but I have never seen one.
 
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