Wiring for studio

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phillyshriv

phillyshriv

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I built a 12x18 studio and now want to supply the feed for [2] 6' electric baseboard heaters wired on 1 thermostat [1500 watts, ~ 6.3 amps draw each] and 2 circuits for lights, stereo system , etc. I figure they will be on [2] 15 amp breakers.
The studio is about 175' from the main house. The main house has a 200 amp service and panel. Plenty of space in the box.
What gauge service wire can I get by with to supply the above? Would 10-3 work? 8-3?
I was thinking I would need to run it in conduit 18" below ground. Or do I use a UV resistant/outside cable?
I need only enough room in the new studio box for a main breaker, a double breaker [probably 20 amp?] for the heaters, and [2] 15 amps for the duplex/lights. But I can only find a small 100 amp box that will allow me the required space. Do I have to use 100 amp service wire to feed that?
And just to make it interesting - I was thinking of having a "switch" in the main house so I could turn everything off in the studio without trekking out there or down to the basement where the main panel is- i figured i'd get a small box with an appropriate breaker.
Thanks for any help.
 
slownsteady is correct, this is a loaded question that will take several members to help get all the answers.
Personally, I prefer conduit versus direct burial cable. Calculations for voltage drop will have to be made in regards to the 175' run. You may have to de-rate the wire size. As far as a 100 amp service box, you will have to match the wire to the box as you don't want the wire to burn up before tripping the 100-amp breaker. In regards to the switch in the house, you could always just flip the 2-pole breaker that feeds the box in the studio.
 
Here is the basic table you see a lot.

http://encorewire.com/wp-content/uploads/amp voltage.pdf

Here is a calculator.

http://www.gorhamschaffler.com/wire_size_calculator.html

It looks like at 240v, copper wire, single phase, 50 amps, 175 feet you will need #4

I am not an expert but I would think you would want a sub panel in your remote building something like 50 or 60 amp given you have the 200 amp service in the main house that shouldn’t be a problem. I also would want it run in conduit if it was mine. A little reserve sizing won’t hurt as there is always something that will come along you might want to add.
 
That building will NEVER see 50A @ 240V by his description. More like 20-25A @ 240V.

Personally I'd run #6AL to a small panel in the studio fed by a 40A breaker in the main. This is of course if there is no real chance of expansion or much heavier draws later on.
 
Thanks for that reply speedy pete. The consensus seems to be 6 wire from a 40 amp breaker run in conduit to the studio. The small 100 amp box I have for the studio came with a double 100 amp breaker, double 30 amp and 2 single 15's. I was planning on using the 15's for the duplex's and lights, the double 30's to feed the heaters. What would you suggest for the main in the studio?
6' Ground bar at the studio, yes?
I am also planning on having a 60 amp a.c. disconnect switch in the garage, so I can just reach out the garage door and hit the switch when the power gets left on, rather than schlepping downstairs to the main.
No future add-ons to electrical - this is it.
Any input much appreciated.
 
Leave the 100A main in the studio panel. It is only serving as a disconnect so it's fine. And yes, you need at least one 8' ground rod at the building, possibly two. Check with your inspector.
Also, WHY the 30A for the heaters??? Working with #10 when you don't need to is really annoying, and you certainly don't need it for 12A.
 
speedy petey said:
That building will NEVER see 50A @ 240V by his description. More like 20-25A @ 240V.

Personally I'd run #6AL to a small panel in the studio fed by a 40A breaker in the main. This is of course if there is no real chance of expansion or much heavier draws later on.
Click to expand...



I haven’t ran the numbers on his job and if its 50A @ 240V or 25A @240V. He will have some fixed costs. He has to dig 175 foot of trench and lay 175 foot of conduit. He has to hire an electrician to install it all and have it all inspected. And he has to backfill 175 foot of trench and landscape costs. The real differential costs is going to be the wire and slightly larger rated devices. Not to mention the total cost of building the building. I guess I was figuring given one chance to do it why not give yourself room for the unexpected given the main house has more than enough capacity with a 200 amp panel. Not to mention the improvement in voltage drop with electric heat.

The house I just bought was rewired a few years ago it has a detached garage and whoever made the call put in a 100 amp sub panel in the garage with underground supply wires that run a similar distance. Even though 95% of the time I draw zero amps out there I am very glad they thought ahead and was a plus factor when buying the home.

I wish they would have run some communication wire at the same time.

The OP wants to be able to kill the building from the house I guess that’s ok but if it was me I would forget the next day to turn it back on and walk out to the building only to find it cold and have to walk back to the house to power it up. I would want a wire ran back to turn on an outside light or something on a 3way switch for walking out there at night.
 
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