Electrical question to kick around ...

[Alchymist]

Was just wondering about this last night - no plans, as I haven't hit the lottery yet.

Scenario - large house, detached garage, and further detached large shop. 400 amp (320) service to the large shop - one 200 amp feed to shop 200 amp panel, second one to a transfer switch (in the shop) that feeds the house 200 amp panel, whole house genset on transfer switch. All pretty much straightforward.

OK, the kicker - when genset is running (Utility company power fail) - shop lights need to be on the genset. How would you all sparkies do it?

Kicking the can in 3, 2, 1......

 

[klassenl]

Dedicated emergency panel in the shop with a sub panel off that on to an emergency panel in the house.

 

[nadogail]

When, and if, the lottery sends me a check I will apply conscious thought to the question.

At present I am more concerned about being struck by lightning which has a much higher probability.

I buy lottery tickets only with my Entertainment Money

 

[Norcal]

Dedicated emergency panel in the shop with a sub panel off that on to an emergency panel in the house.

Not going to work as only one feed to the structure is allowed, but a 2nd transfer switch would work.

 

[brewchief]

I've got a friend that will have a setup like this if he ever builds a house on his property.
So far my thought was to mount a 200 amp feed through panel at the shop after the transfer switch on the feed to the house and use a couple circuits in that panel for a light circuit and to feed the well.



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[klassenl]

Not going to work as only one feed to the structure is allowed, but a 2nd transfer switch would work.

You could feed the entire house off the gen/emergency panel.

 

[Barnabas]

Just get a 400 amp generator and power the whole system.

 

[dcg9381]

I have a in-progress implementation for something similar. 320A feed - dual 200A panels. One panel feeds the shop. One panel feeds the house.

Course, the house doesn't exist yet. The shop does. Because my priorities are right!

Like you mentioned, you only get one 200A "transfer switch" for a whole-house genset.

The way I decided to do it was have the shop on it's own service panel.
The house is on it's own 200A service, to a transfer switch, geneset, and generator will auto start. So the house is gen-set powered, but not the shop.

My plan is to do a no-no: Simply run a 20A line from the house into the shop to power the lighting. I believe this "may" be a violation of NEC code (some discussion on dual-powering a building and branch circuit vs service conductor circuit) - but it solves the same problem for me.

My situation is slightly different because my shop has solar panels, which are not easily compatible with a whole-house generator.

 

[Alchymist]

Pretty sure there is no 'may" about it - one feed to the building as far as I know. Reason being someone could cut the main breaker in the entrance panel and there would still be live circuits in the building.

 

[dcg9381]

I think you're responding to me indication that electrical feeds to a single building isn't NEC (or code?) legal.

The other way I see to do it would be to put the lighting circuits on a UPS or other battery backup. Modern LED lighting is both bright and reasonable draw... Depends on what the OPs goal is.

 

[alfredeneuman]

Certain numerous special feeds to 1 building are legit as far as the Code is concerned.
(240 delta 3 phase 3 wire and a separate 120/240 single phase comes to mind)

 

[Alchymist]

I think you're responding to me indication that electrical feeds to a single building isn't NEC (or code?) legal.

The other way I see to do it would be to put the lighting circuits on a UPS or other battery backup. Modern LED lighting is both bright and reasonable draw... Depends on what the OPs goal is.

Now there's an interesting solution.

 

[Alchymist]

Certain numerous special feeds to 1 building are legit as far as the Code is concerned.
(240 delta 3 phase 3 wire and a separate 120/240 single phase comes to mind)

True, but you don't see that in residential or even small commercial shops.

 

[Alchymist]

Just crossed my mind - (I know, short trip) - 120 volt to 24 volt transformer in house, say 10 amp @24 volts. Two wire copper run to garage, small power supply to convert to DC, and a set of LED lights scattered around the shop. Single switch on the incoming 24 VAC to control LED lights. Regular lighting off the garage panel. OK - someone blow holes in it .....

 

[cybrdyke]

Lights can be put on an inverter, mounted next to the lighting panel. Inverter will run the lighting circuit for 90 minutes after power fails, as per code, before it needs to be charged. Charging is done when the power is normally "on". The inverter is sized based on total watts of the lights to be operated. They're expensive, but they work well. They come in all sizes, from the smallest that will run one fixture, up to very large that will run an entire building.
CD

 

[MFolks]

Maybe this brand; http://www.kohlerpower.com/home/home-generators/selector#your-home

 

[jade97]

My house has a 400 amp service going into my 400 amp ats, then there are 2 200 amp.panels.

I would do the same in your case except one of the 200 amp panels would be in the garage

 

[Shiftless]

Lights can be put on an inverter, mounted next to the lighting panel. Inverter will run the lighting circuit for 90 minutes after power fails, as per code, before it needs to be charged. Charging is done when the power is normally "on". The inverter is sized based on total watts of the lights to be operated. They're expensive, but they work well. They come in all sizes, from the smallest that will run one fixture, up to very large that will run an entire building.
CD

I think this is the best idea so far.
.
My needs are MUCH simpler than Alchymist’s
My set up is a single 12 volt RV/marine battery connected to a 1000 watt inverter. It will run a few led lights for a really long time but the only thing I really care about is the 1/3 HP sump pump. Winters are mild here so no vital need for power for the gas furnace. Outages are rare and usually for only an hour or so. The fridge and deep freeze will be fine.