Single phase / 3 phase shop panel questions

[Snip]

First off, Happy Thanksgiving to all here. We will be building a 40x64 shop this spring in Tennessee. Power company says there is 3 phase available on the pole closest to the shop. Can single and 3 phase be in the same panel? Shop will be located between the pole and an existing outbuilding that has its own meter, separate from the house service. I think this affords me the option of relocating the meter to the new shop and using a 200 amp panel and running a smaller sub panel (lights and fans only, no heat) to the outbuilding, please correct me if this is not a good idea. Most of my equipment with the exception of the mill (it has a converter on it) is single, welders, plasma, lathe ect. Would bringing 3 phase into the building require a separate meter and/or panel or would they both use the same? If upgrading to three phase is a minimal cost upgrade I would consider it as it opens possibility's on equipment upgrades in the future.
If i understand it correctly running 3 phase equipment with a converter reduces the HP output of the equipment, once again please correct me if I am misinformed on this (or anything else here also)
TIA for your input and advice.

 

[MrGreen]

It depends on the service. 208/120Y gives you both, but I hate 208.

My shop has 240v corner tapped Delta high leg. You have both 3 and single in those panels as well. Not a very common service anymore, it's better than 208. Expensive to step up to 480v, I have two 225kva step ups.

I prefer 480/277Y, but you will have to use transformers to get you to 240/120 single phase. This service is probably the easiest/cost effective way to get whatever voltage you desire via transformers at reasonable costs.

Sent from my SM-N960U using Tapatalk

 

[jeepxj]

get 480 3p and then put a small transformer in for your 120/240 panel in. extremely common.
just keep an eye on ebay for a good used unit: ex https://www.ebay.com/itm/Square-D-7...458757&hash=item2ad9fc4166:g:zpEAAOSwT9NdzcVU

 

[Terry D]

See if there is any additional cost from your utility for bringing it to your building. 120/208 wye is a good versatile system. You can get your 120 loads, loads that just need 2 hots and you 3-phase loads out of it. And yes, it will all come out of one panel with one meter. Sounds like that you have one piece of equipment that is 3-phase, it would give you the option to get more 3-phase equipment down the road. I'm in St Louis, there is some 3-phase delta here, becoming a thing of the past here. To get 120v out of 240v delta, you have to center tap one of the transformers, and as MrGreen said, you get a high leg. We don't have that system here, just straight 240 and 480 delta. And our utility does even want to provide it anymore on new services, only special circumstances.

 

[Mr. T]

My shop has 240v corner tapped Delta high leg.

Ive seen corner ground delta (one phase bonded to ground) and high leg delta(one phase with a center tapped winding bonded to ground), but not what you describe here.

 

[MrGreen]

Ive seen corner ground delta (one phase bonded to ground) and high leg delta(one phase with a center tapped winding bonded to ground), but not what you describe here.

My fault, mine is a center tapped. Although the utility service keeps calling it corner tapped, but that wouldn't give me the high leg.

High leg annoys me since someone wasn't very consistent keeping it on the B phase for all the sub panels.

Sent from my SM-N960U using Tapatalk

 

[wyliesdiesels]

First off, Happy Thanksgiving to all here. We will be building a 40x64 shop this spring in Tennessee. Power company says there is 3 phase available on the pole closest to the shop. Can single and 3 phase be in the same panel?

This really depends on what type of 3-phase they have

480Y/277 will not give you 120v.

240D/120 will however most PoCos arent installing that anymore

208Y/120 will give single phase between all 3 phases and neutral.

What kind of loads will you have?

Shop will be located between the pole and an existing outbuilding that has its own meter, separate from the house service. I think this affords me the option of relocating the meter to the new shop and using a 200 amp panel and running a smaller sub panel (lights and fans only, no heat) to the outbuilding, please correct me if this is not a good idea. Most of my equipment with the exception of the mill (it has a converter on it) is single, welders, plasma, lathe ect. Would bringing 3 phase into the building require a separate meter and/or panel or would they both use the same? If upgrading to three phase is a minimal cost upgrade I would consider it as it opens possibility's on equipment upgrades in the future.

The meter requirement depends on the voltage of the 3 phase service and the amperage. If over 400 amps, you would get CT metering in a cabinet.

As far as running to the outbuilding, that could work. If you get 480v service, you would need a step down transformer.

If i understand it correctly running 3 phase equipment with a converter reduces the HP output of the equipment, once again please correct me if I am misinformed on this (or anything else here also)
TIA for your input and advice.

That only applies to static converters.

It depends on the service. 208/120Y gives you both, but I hate 208.

My shop has 240v corner tapped Delta high leg. You have both 3 and single in those panels as well. Not a very common service anymore, it's better than 208. Expensive to step up to 480v, I have two 225kva step ups.

I prefer 480/277Y, but you will have to use transformers to get you to 240/120 single phase. This service is probably the easiest/cost effective way to get whatever voltage you desire via transformers at reasonable costs.

Sent from my SM-N960U using Tapatalk

My fault, mine is a center tapped. Although the utility service keeps calling it corner tapped, but that wouldn't give me the high leg.

High leg annoys me since someone wasn't very consistent keeping it on the B phase for all the sub panels.

Sent from my SM-N960U using Tapatalk

Thats odd that the PoCo doesnt know the proper name of the service theyre providing.

If someone wasnt consistent with the hi-leg bus placement, have you considered fixing it?

 

[MrGreen]

This really depends on what type of 3-phase they have

480Y/277 will not give you 120v.

240D/120 will however most PoCos arent installing that anymore

208Y/120 will give single phase between all 3 phases and neutral.

What kind of loads will you have?



The meter requirement depends on the voltage of the 3 phase service and the amperage. If over 400 amps, you would get CT metering in a cabinet.

As far as running to the outbuilding, that could work. If you get 480v service, you would need a step down transformer.



That only applies to static converters.





Thats odd that the PoCo doesnt know the proper name of the service theyre providing.

If someone wasnt consistent with the hi-leg bus placement, have you considered fixing it?

As I have been updating lighting, cleaning up dead end runs, trying to identify stuff, etc. I have been changing it in my panels where needed. After 50+ years, EMT, wiring, panels, get to be a mess from no one actually caring.



Sent from my SM-N960U using Tapatalk

 

[MrGreen]

They also hate that service, have offered to change it, but that would open up a huge can of worms trying to deal with the myriad of sub panels and strange runs all over inside a 60k sqft building.

I have 5 machines that draw around 150 amps at 480 and are way too much work to switch over to 240v.



Sent from my SM-N960U using Tapatalk

 

[Snip]

Thank you to all. At this point I think my next step is to contact the power company and see what we are working with and come back with more info.

 

[dr_clyde]

My old shop was 208 wye and it sucked. Some equipment, especially welders, really likes the extra volts in a 240 setup. Some of my machines wouldn’t output higher amps because the internal computer sensed low enough voltage to think it was on 120v while actually on 208v.

My current shop is 480 delta with a transformer running the low voltage loads. Way way better for a shop.

 

[Norcal]

My old shop was 208 wye and it sucked. Some equipment, especially welders, really likes the extra volts in a 240 setup. Some of my machines wouldn’t output higher amps because the internal computer sensed low enough voltage to think it was on 120v while actually on 208v.

My current shop is 480 delta with a transformer running the low voltage loads. Way way better for a shop.

Anything 600 volts and less is low voltage.

 

[wyliesdiesels]

My old shop was 208 wye and it sucked. Some equipment, especially welders, really likes the extra volts in a 240 setup. Some of my machines wouldn’t output higher amps because the internal computer sensed low enough voltage to think it was on 120v while actually on 208v.

My current shop is 480 delta with a transformer running the low voltage loads. Way way better for a shop.

Buck boost transformers wouldve been your friend there

 

[alfredeneuman]

If the property is zoned residential, 480 wouldn't be an option.
Residential properties are limited to 240 volts.

 

[jeepxj]

If the property is zoned residential, 480 wouldn't be an option.
Residential properties are limited to 240 volts.

is that every state?

 

[Stuart in MN]

is that every state?

Yes.

 

[American Locomotive]

I agree about 208v sorta being a drag. Especially when you start getting into big motors/loads where the current draw difference between 208 and 240v starts to actually matter. I've even seen motors that were dual-rated for 208/230v, but had a lower service factor on 208v.

But unless you want to get a big 'ol transformer, 208/120 is basically the standard these days. However I'd take 3 phase over not having 3 phase, even if it means a 208/120 system.

Anything 600 volts and less is low voltage.

If you're going to be needlessly pedantic, at least be accurate about it. There is no one single definition for "low voltage" and it all depends what industry you're in, what standards you're following and what specific portions of that specific standard you're following.

- The IEEE defines anything below 1000 vAC as low voltage.
- British Standard BS 7671 defines high voltage as everything above 1000 vAC
- NEC defines low voltage as anything below 60vAC for distribution systems (but has different definitions for equipment and transmission systems).
- Certain UL standards define low voltage as anything below 20v.
- The SAE defines high voltage as anything over 60vDC/30vAC

In the context of his shop, any equipment below 480v is a "lower voltage" load, and could be accurately described as "low voltage". His 480v equipment could be accurately described as "high voltage" within the context of his shop.

Now excuse me while I go install a new 220v circuit for my welder.

 

[Norcal]

I agree about 208v sorta being a drag. Especially when you start getting into big motors/loads where the current draw difference between 208 and 240v starts to actually matter. I've even seen motors that were dual-rated for 208/230v, but had a lower service factor on 208v.

But unless you want to get a big 'ol transformer, 208/120 is basically the standard these days. However I'd take 3 phase over not having 3 phase, even if it means a 208/120 system.


If you're going to be needlessly pedantic, at least be accurate about it. There is no one single definition for "low voltage" and it all depends what industry you're in, what standards you're following and what specific portions of that specific standard you're following.

- The IEEE defines anything below 1000 vAC as low voltage.
- British Standard BS 7671 defines high voltage as everything above 1000 vAC
- NEC defines low voltage as anything below 60vAC for distribution systems (but has different definitions for equipment and transmission systems).
- Certain UL standards define low voltage as anything below 20v.
- The SAE defines high voltage as anything over 60vDC/30vAC

In the context of his shop, any equipment below 480v is a "lower voltage" load, and could be accurately described as "low voltage". His 480v equipment could be accurately described as "high voltage" within the context of his shop.

Now excuse me while I go install a new 220v circuit for my welder.

Be sure to follow the proper color code for 220, blue for neutral and brown for hot.

 

[wyliesdiesels]

is that every state?

Yes sir

 

[dr_clyde]

I know of at least two people in Michigan who have 480v service at their personal residence. They have separate meters that are on commercial rates, but are not in a park or any sort of industrial or commercial area.

 

[dr_clyde]

Buck boost transformers wouldve been your friend there

I’m not going to install special transformers for an occasional load. That wouldn’t pay back on investment.

I just used a different machine.

 

[alfredeneuman]

I know of at least two people in Michigan who have 480v service at their personal residence.

Michigan doesn't follow the NEC on residential. (Michigan Residential Code).
Only the States that have adopted the NEC for residential are subject
They do have to follow the NEC on non dwellings

 

[dr_clyde]

Michigan doesn't follow the NEC on residential. (Michigan Residential Code).
Only the States that have adopted the NEC for residential are subject
They do have to follow the NEC on non dwellings

Ahh, got to love national codes vs state codes. What a lovely thing.

Got to make sure the waters are sufficiently muddy for any sort of system.

 

[wyliesdiesels]

I know of at least two people in Michigan who have 480v service at their personal residence. They have separate meters that are on commercial rates, but are not in a park or any sort of industrial or commercial area.

Pretty foolish to allow such service for residential as majority of people have no clue how to work on 480v systems, which are unforgiving. Arc flash is no joke

 

[MrGreen]

Pretty foolish to allow such service for residential as majority of people have no clue how to work on 480v systems, which are unforgiving. Arc flash is no joke

If you are inquiring about getting a 480v 3phase service to your detached garage in town, I am fairly certain you just may have some idea what it is.

Sent from my SM-N960U using Tapatalk

 

[Norcal]

Pretty foolish to allow such service for residential as majority of people have no clue how to work on 480v systems, which are unforgiving. Arc flash is no joke

I understand a 480V arc is hotter then the surface of the sun, anyway I look at it if involved with one your better off dead. I agree that 480V has no business in residential, although in Germany 400/230V 3Ø is common in residences and is used to power domestic ranges.

 

[Stuart in MN]

Michigan doesn't follow the NEC on residential. (Michigan Residential Code).
Only the States that have adopted the NEC for residential are subject
They do have to follow the NEC on non dwellings

The way I read it Michigan Residential Code follows the NEC, with some amendments. It does say services shall be 120/240vac.

E3602.4 Voltage rating

Systems shall be three-wire, 120/240-volt, single-phase with a grounded neutral. [220.82(A)]

https://up.codes/viewer/michigan/mi-residential-code-2015/chapter/36/services#36

 

[Snip]

So today I call the local power company and inquire with the service personal as to what variation of 3 phase that is available to my property. I am put on hold for a few minutes and when they come back on the line she tells my that 3 phase is not available on that line? Now I'm confused because about a year ago I met (on the property) with one of their engineers to inquire about the cost to move one of the poles. While discussing moving the pole (not even close to in any budget) he was the one that told me it was on the line/pole.
I guess at this point I just wait until I am living on the property and am dealing with the building and electrical contractors. Is there a chance that it may be there and not available to residential customers? I guess it's not a huge deal if not, just would open options if/when I decided to upgrade equipment/welders.
Thank you to all that contributed your knowledge and suggestions .

 

[wyliesdiesels]

Go look up at the pole. Do you see 3 primary conductors on the very top crossbar of the pole?

If so, then they may not allow 3 phase to residential.

If not, then the engineer was full of it....

take a pic of the pole and post it here...

 

[Snip]

Unfortunately we still live in Colorado and cannot do that at the moment. Wish I could be a little more locally active. Trying to plan, talk to contractors when not in person is trying. When we are able to be on site trying to get meet vendors or get them to show up, return calls ect can be hit and miss. We want to be residents/ onsite when the build is going up but are trying to do some of our pre work / planning prior to our move.

 

[Paperman]

One thing to think about when pulling in 480 is the cost of keeping the step down transformer energized. My old dry GE was pulling any where from .4-.6 amps with no connection on the low side. It was old but worked great for 40 years, it just cost money to keep on all the time.

 

[wyliesdiesels]

One thing to think about when pulling in 480 is the cost of keeping the step down transformer energized. My old dry GE was pulling any where from .4-.6 amps with no connection on the low side. It was old but worked great for 40 years, it just cost money to keep on all the time.

Theres a solution for that. If there is nothing in the shop that needs power when its closed/not in use, just open the breaker or disconnect feeding the transformer...

 

[4 FN 27]

If the property is zoned residential, 480 wouldn't be an option.
Residential properties are limited to 240 volts.

is that every state?

Yes.

Hmmmmm...I had 3 Phase brought onto my property in 2009. I just had to pay for the 1/2 mile run. 5 Poles, 3 Transformers and the 1/2 mile of Wire.

Hook up to the house and the building were free.

All I did was ask.

 

[wyliesdiesels]

Hmmmmm...I had 3 Phase brought onto my property in 2009. I just had to pay for the 1/2 mile run. 5 Poles, 3 Transformers and the 1/2 mile of Wire.

Hook up to the house and the building were free.

All I did was ask.

every PoCo is different and has different rules. no point in comparing...

 

[4 FN 27]

every PoCo is different and has different rules. no point in comparing...

Not comparing. Just correcting bad info. Ask before you believe others and dig in and find out.

Bad info is why my first house didn't have a Floor Drain. My builder said it was illegal. I took his word for it and found out later my neighbor had a Floor Drain (different builder) and asked how he got that. He said he asked the city and they said yes...no Flammable Waste Trap needed either...Maplewood, MN 1994.

Asked my builder and he said "I heard they were illegal." He never checked nor did I. 15 years of slop in the garage pissed me off...I was more mad at myself for not checking.

Ask and dig...you may be able to do it.

 

[matt_i]

I lived in TN for a couple years and was headed down the road of building a shop with a utility 3 phase service.

I had a couple meetings with a DREMC (duck river emc) field engineer. I was well into $7k investment, 10 years ago, to get to a meter base. This utility fronted the 3 new transformers on the power pole as well as the wiring (conductors) to the meter base but wanted some kind of assurance that they could be paid back, slowly, over time, with advanced electricity consumption. In a residential shop thats never going to happen and the utility isn't an institution that caters to freebies for advanced home shop machine hoarders

Eventually I moved and never built but my conclusion is you're better off either running a RPC or buying a Phase Perfect.

Then you run on single phase service just like everyone else. If and when you move, you pull the RPC or PP and probably your 3 phase distribution system and you set it up at a new location.