Stand-alone or sub-panel?

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Old 10-25-17, 09:24 AM
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Stand-alone or sub-panel?

I have an outbuilding that was formerly used in an industrial application, monitoring seismic equipment. It was completely functional and wired with it's own main shutoff switch, a 600v -->120/208 3 phase transformer, and 200 Amp main panel (100 Amp 3 pole main breaker is already installed). Panel supplies standard 110 lighting and power outlets and also powers 2 HVAC units - 208/230v single phase. When it was decommissioned, the 600v main feed to the transformer was simply cut off .

Seems to me the simplest solution to bring power back into the outbuilding is to split off from my 600v service, right before the main panel into the house and connect that new line to the 600v feed that was cut off at the outbuilding.

Alternatively, I could install 100amp breaker in the house and run a 240v feed directly to the panel in the outbuilding, making it a sub panel to the main in the house. This seems like more work and I lose the 3 phase power.

I realize, either way, there is more to it, to do it properly and safely. Either way, it is a short run of less than 20 feet. Just looking for a starting point. Any reason why Option 1 isn't a good solution?

TIA.

Shawn

EDIT: added photos. ALL photos are of the outbuilding electrical system
 
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Last edited by oneshotshawn; 10-25-17 at 10:00 AM.
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Old 10-25-17, 06:38 PM
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That is quite the industrial set up you have there.

Just because the breakers and other equipment are marked with a 600 volt rating does not mean that it is fed with 600 volts. That is the maximum voltage the equipment can handle. Standard common equipment will come in two ratings, 250 volt and 600 volt. 250 volt will be used for anything from 120/240 single phase, to 120/240 or 120/208 3 phase. 600 volt equipment is normally used for 277/480 volt 3 phase, or 347/600 volt 3 phase.

I have never seen a house that has a 600 volt service and can't think of a reason why a house would need that kind of voltage. Almost all houses in the US is fed with a 120/240 volt single phase service. You are in Canada so things might be different. Also, in order to get three phase out of the transformer, you need to have a three phase feed.

To help you better, let's start at the source. Post a picture or your homes service, both meter socket and main panel, and we can see what you have.
 
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Old 10-30-17, 12:08 PM
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Just because the breakers and other equipment are marked with a 600 volt rating does not mean that it is fed with 600 volts. That is the maximum voltage the equipment can handle.

I see what you mean here.

To help you better, let's start at the source. Post a picture or your homes service, both meter socket and main panel, and we can see what you have.

From the meter, it looks like I have a 240v Single Phase service to the house. The panel reads "125Amp 120/240v AC 1 Phase 3 Wire"

Also, in order to get three phase out of the transformer, you need to have a three phase feed.

I guess this means the safety switch and transformer I have on the outbuilding are of no use in this application (30Kva 600v Primary ---> 120/208 3 Phase Secondary) and can be bypassed completely?

The cable coming from the farm service splitter to the house MAIN panel is marked "2C #2 ALUM XLPE USEB90 Reduced Neutral" and is accessible in the crawl space before the MAIN panel (ideal for a splitter connection? Same as the farm service splitter up line?)

Either way, (split off before the house MAIN and feed the outbuilding as a stand-alone MAIN panel, or install a 100 Amp sub-feed from the house MAIN and run the outbuilding as a sub-panel) it looks like I'll need to feed directly to the outbuilding panel, eliminating the safety switch and transformer all together, ya?

Thanks,

Shawn
 
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Old 10-30-17, 12:41 PM
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Yes it looks to me like you have a standard 100A 240V single phase service. There are a couple ways to approach it, but the most straightforward is probably installing a 100A breaker in your house panel and feeding the shop panel from that.

However, there would be a pretty good case to be made for installing a main distribution panel somewhere centrally on the property and feeding each building separately from that.

Are you sure those HVAC units are 230V single phase? If they are three phase units they will not work on single phase power.

While there are tricky ways you might be able to re-use that industrial panel I'd be tempted to just scrap the panel, disconnect and transformer and put in a standard residential panel in its place. See if you can find an electrical parts reseller to buy it for used parts -- it all looks to be in very good condition. It might make enough to completely fund your project.
 
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Old 10-30-17, 01:37 PM
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I don't see any three phase breakers in that panel, other than the main, but all those breakers look to be GFI type. That's a fortune just in breakers.
 
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Old 10-31-17, 08:48 AM
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Talking Stand-alone or sub: Revision 2

Are you sure those HVAC units are 230V single phase?

I'm pretty sure... (see pic)

While there are tricky ways you might be able to re-use that industrial panel I'd be tempted to just scrap the panel, disconnect and transformer and put in a standard residential panel in its place. See if you can find an electrical parts reseller to buy it for used parts -- it all looks to be in very good condition. It might make enough to completely fund your project.

I'm not smart enough for tricky . Unless my electrician has a good way to reuse the panel, I'm kind of leaning this way myself. Seems like a lot of expensive equipment, that I'll never need. Sell off the safety switch, transformer and panel (plus there's a bunch of low voltage wiring and controls for monitoring seismic equipment) and replace with a simpler residential panel or sub.

Revised property/layout diagram attached.
RE.: Grounding - in either option, can I ground the outbuilding panel to the ground rods used for the MAIN house panel? They are between 4 and 6 feet away from the outbuilding. (see diagram)

Thanks again.

Shawn
 
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Last edited by oneshotshawn; 10-31-17 at 08:52 AM. Reason: typo
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