Residential 3 phase

[gar]

130305-1957 EST

How often do you encounter 3 phase power supplied to a modest size residence, like 3000 to 4000 sq-ft?

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[Sierrasparky]

never unless it's a multifamily and fed three phase. but most of that time it is only three phase to the MSB.

 

[texie]

130305-1957 EST

How often do you encounter 3 phase power supplied to a modest size residence, like 3000 to 4000 sq-ft?

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As sierrasparky said, never unless it is multi family. Then it will be 208Y/120 if it is used.
However, if you are talking about an older neighborhood in the south platted in the 50's or 60's, when A/C was just coming around, in some areas it was possible to get 240/120 4 wire service to support the A/C load as single phase A/C was not as common in the early days. It was often accomplished at the service with a so called "delta breaker" installed in a single phase panel (now prohibited by the NEC) to feed just the A/C.

 

[augie47]

130305-1957 EST

How often do you encounter 3 phase power supplied to a modest size residence, like 3000 to 4000 sq-ft?

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In 40 years, I think I have encountered two in residences that you describe.

 

[ActionDave]

In 40 years, I think I have encountered two in residences that you describe.

If you are as old as you claim to be then you must have got started late.

For me twenty four years and not a one.

 

[mivey]

130305-1957 EST

How often do you encounter 3 phase power supplied to a modest size residence, like 3000 to 4000 sq-ft?

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As texie noted, just a few every now and then on older homes b/c of 3-phase A/C units. Much less than 1/2%, probably on the order of 0.2% as a guess.

 

[iwire]

130305-1957 EST

How often do you encounter 3 phase power supplied to a modest size residence, like 3000 to 4000 sq-ft?

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Here in my area I have never seen it.

 

[augie47]

In 40 years, I think I have encountered two in residences that you describe.

Spent the first 10 years inside an industrial environment.... you made me stop and think. I put my first tool belt on in 1962.
(As I recall at $2/hr, almost twice the minimum wage)_

 

[gar]

130306-0842 EST

There are at least two houses in our neighborhood with 3 phase. texie's comment is probably the reason, 1960s. But note we are in the north.

I will have some further comment later.

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[GoldDigger]

130306-0842 EST

There are at least two houses in our neighborhood with 3 phase. texie's comment is probably the reason, 1960s. But note we are in the north.

I will have some further comment later.

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Electric heat and cooking too by any chance? That would be a bigger load than A/C.

 

[Volta]

Only once as new in my 1/4 century, weirdly in the foothills of Colorado, early nineties. Single family, nothing else close.

 

[hillbilly1]

I've only seen a couple over the years, one in the Dominican Republic, one in Albany, Ga., it was 480 volt three phase (the guy called it his hunting lodge LOL!) and one inside the perimeter of Atlanta. (I think that guy had something to do with Coca Cola!)

 

[gar]

130306-2035 EST

Virtually everyone around here has natural gas heat. Some new or remodeled homes have ground based heat pumps. Gas probably costs about 1/3 of electricity per unit of energy. I haven't checked this ratio lately, but gas has gone down some and electricity has risen a lot.

Visited my neighbors tonight. He is a former dean of public health (math, statistics --- still teaches) and she is a mechanic, nurse, and medical malpractice lawyer.

Their setup is an open delta, with a wild leg. Voltages 121, 122, and 217 relative to earth. The wild leg is a little high because of no loading at this time of year. House built in 1960. These neighbors are on a different primary than I am on. Gas heat, hot water, dryer, range top, and fire place are major gas energy loads.

Another neighbor is on my primary with 3 phase output, but I don't know the house location. This information was from a DTE serviceman when our last outage occurred.

First said neighbors have been using a Honda variable speed 7.5 kW portable gasoline generator, and a 6 circuit manual transfer switch. I use a 5 kW Honda portable. Their portable generator is a problem because they have to have someone else run it when they are traveling and power is lost. Their major needs are refrigeration, freezer, fish, heat, and a water pump for a fountain and cascading water path in the backyard. If the pump stops for a few minutes they lose about 1000 gallons of water into the street. When they are present then there are additional small loads required.

The big three phase air conditioner is not required under emergency conditions. The smaller air conditioner also can be classified as not required. It would be totally impractical to try to backup the three phase unit.

It does make sense to backup the entire house rather than just a few circuits. This can be done with a transfer switch to the 120-0-120 panel. Presently fused at 100 A. No mechanical problems to do this.

The size backup generator selected may determine how to handle the small air conditioner.

What initially surprised me was that two close neighbors to me had three phase in their homes. There may be more close by that I don't know about. Many houses in my area will date to the 50s and 60s, one to the 1860s, a mansion to the 1910s (Hoover ball bearing founder and owner, now a bank). So a wide variety of homes. Our whole area is three phase delta for the primary.

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[norcal]

Member 220/221 has posted service change photos where he removed residential 3? services w/ delta breakers & replaced them w/ 1? services....

 

[zbang]

A friend in the LA area (Huntington Beach?) has single -and- three phase in his house, but it was a farm until the 'burbs move in around him. The 3-phase is useful for some of the ancient computers he has.

 

[cowboyjwc]

Never seen it on a single family and it's so rare on even multi family here that a local contractor thought the plans were wrong and installed a single phase on some apartment buildings, turns out the plans were right.

 

[Gary Meerschaert]

I have seen one in our area, owner was a lighting manufacturer at the time.

 

[K8MHZ]

Never seen it on a single family and it's so rare on even multi family here that a local contractor thought the plans were wrong and installed a single phase on some apartment buildings, turns out the plans were right.

Gar is in the DTE area. On their new service request forms you can get 3 phase power to a 'large residence'. Where it says 'type of business', 'large residence' is acceptable.

I live on the other side of the state as Gar. We have Consumers Energy and a linesman once told me that they would not run 3 phase to a single family dwelling and it was even tough to get 3 phase for a large pole barn on residential property.

 

[marti smith]

We have a fairly good amount of homes, ones built in the '60's that are all 3 phase. It is very commom here to do a service change when someone is upgrading their hvac, removing the old for new, single phase for three phase. About the same for new hvac and service upgrade than to get new three phase equipment.

 

[gar]

130307-1051 EST

In our area there are a lot wild leg deltas, open initially and closed if the load increases, for commercial.

K8MHZ I will guess that DTE may have this large house choice to anticipate a substantial expected increase in plug-in hybrid vehicle loads. This would provide better balancing.

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