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Discussion Starter · #1 ·
i am building a barn/garage on the back 40 of my property. i am wondering if i can tap into the breaker box on my second garage close to my house to suppy enough electricity to run lights and garage door opener on my new barn. the distance is roughly 800 feet.

if this is possible, what gauge wire would be best?

i am planning on burying the wire in conduit. will i need a separate ditch for water as well?

thanks for any electrician experts that are willing to respond
 

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How long is the run from the house to the first garage, what is the gauge used on the run to the first garage, How many amp is the breaker to the first garage, what electrical loads are at the first garage???? Is it 110 or 220 ran to the first garage?
 

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You can call your local electrical inspector and he can give you all the local requirements.
In BC Canada you can bury water and power/sewer all together with a foot separation either horizontally or vertically
You need make sure you have room in the shop panel as well.
Their are voltage drop calculators on line, just Google that.
It will need to know distance and load .... 60 or 100 amp panels are the most common.
800 feet is a long run so your wire size is going to be fairly large so the next problem you will run in to is getting it in to the breaker on the feeder panel and the lugs on the sub panel.
 

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Code requires 220 to be buried 24" below the surface, covered up to 12" and a plastic tape laid in the ditch that says "Caution, Electrical power". That tape is like the construction caution tape or the police line tape, only red. then covered the rest of the way.
 

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Discussion Starter · #6 ·
The first garage is 200 ft from an on ground transformer that is 45 ft from my house. I do have a meter on the first garage and therefore power bill is separate from main house.
The breaker box is same size as that on second floor of my house. It has lot of space left in it

I am hoping to run wire to new barn that is 800 feet away using this breaker box
 

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Discussion Starter · #7 ·
Would likely need to dig 2 separate ditches to get water and power from second garage to new barn?

Best to run wire in electric conduit instead of water pipe
 

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Thanks for the data Phunter. Your answer is 2/0 two aught (naught, old English) for a 40 amp delivery circuit at a distance of 800 feet. If you need more current then I will need to recalculate. Forty amps should be more than sufficient for a garage door opener and miscellaneous electric lights. If all you need is a total of 20 amps, then Number 2 wire will minimally meet your needs.
 

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The first garage is 200 ft from an on ground transformer that is 45 ft from my house. I do have a meter on the first garage and therefore power bill is separate from main house.
The breaker box is same size as that on second floor of my house. It has lot of space left in it

I am hoping to run wire to new barn that is 800 feet away using this breaker box
if you have a service entrance at the main garage then you can certainly sub feed the new garage. the easiest way to do that is to:

have a MCB panel in main garage with a sub feed CB feeder to the new garage. (personally i would run 2 pole/ 220) buried per <@[email protected]> comment and sized per addertooths comments, or any of us can do a voltage drop calculation for you.
voltage drop will be less at 220. so really would use less copper to set a new panel then pull 2 circuits.

i would set the new panel in the new garage with MCB as well.

you can use "direct burial" cable if you like. i would recommend you run a second 1" conduit min. and have pull boxes on both ends. easy to put it in now....

now - there are 1,000 ways the details play out... but here are a few pointers to get you started.

you want the new garage to be on its own ground system. the feeders do not carry ground. (isolated conductor - e.g. plastic pipe) you want (2) 10' ground rods bonded to the panel ground buss, and the ground buss bonded to the panel frame.

you can oversize wire all day long, and i would up it to carry 60amp over the distance. if you every wanted to throw a welder or compressor down there you would be covered...

if you want to be very lean... you could just set breakers in the main garage panel and pull circuits to the new garage. but, the work will be the same, the wire won't cost any less and in the end your painted into a corner.

dont get confused by "panel amps" that just the max amperage that panel is framed to go to - in other words - you can take a 225amp panel and put a 40 amp MCB in it... also, you don't have to get a MCB panel in the new garage, you can "back feed" the panel - what that means is a MLO panel, but the "first" breaker are the feeders going in to energize it. i did this in my garage simply because i couldn't get a MCB panel the weekend i was wiring it up. when your dealing with smaller loads and panel "back feed" is not uncommon at all. you can get a little 12 pos 60amp panel at home depot with breakers for like 40 bux....

you can bury the water and power in the same trench - you just need to have a dimension separation per you local codes. but if your taking water down there, will there be sanitary? or just an exterior hose bib?

feel free to hit me up if you have any questions on the wiring / grounding etc...
 

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can you take a pic of the main garage panel, with the covers taken off? what is the wire size and or breaker feeding the panel? we can determine how much spare "capacity" you have.
 

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FitFan brings up a VERY good point, and yes, my calculations were assuming 220 service, which gives you two 110V circuits. Code normally does not allow power socket and lighting to be on the same circuit.
 

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FitFan brings up a VERY good point, and yes, my calculations were assuming 220 service, which gives you two 110V circuits. Code normally does not allow power socket and lighting to be on the same circuit.
for residential you can have convenience outlets and lighting on the same circuit. however, i don't recommend it for a garage. i would wire the lighting 15 amp/14awg and the outlets 20amp/12awg.

yea - once you pull 220... you can pretty do whatever you want, you can break out 120v circuits or a 220 circuit. the voltage drop is lower, its a single set of feeders and the panel and breakers are cheap. and... its really "better and safer"
 
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