Electrical question

[pinetree10]

I've searched high and low on the internet and keep finding contradictory opinions on this subject so I figured I'd run it by you guys.

I built a detached garage about 70 feet from my house and I intend to use it mostly for storage of my new tractor and all other related yard and garden tools and equipment. I put 3/4" PVC conduit in a deep trench from the new garage to my existing attached garage. My intention is to run 10-2 Romex wire from my 200 amp panel in the basement (which is at the other end of the house of course. Why would it be easy?) to where the new conduit starts at the outside wall of the existing attached garage, then stranded 10 wire (black, white, and green) from the attached garage to the new detached garage. Once inside the new garage I was going to switch to 12-2 Romex wire for the few fluorescent lights and general purpose receptacles I want to put in the new garage. I plan on feeding the circuit with a 20 amp GFCI breaker in the basement panel and the biggest things I'll be using in the new garage are a small bench grinder (plate says 2.5 amps and I know startup can be a bit higher) and occasionally a small compound miter saw (plate says 15 amps and I know startup can be higher) or maybe a leaf blower or small hand drill. Bottom line is I only want to run one circuit to feed both the lights and the plugs because this new garage is not going to be a welding shop or auto repair facility, at least not while I live there. I just want some adequate power out there without getting carried away with a whole new sub panel. I realize lights and receptacles are usually separated and that if I do trip the breaker I will have to make a long walk to the basement, but I really just want to keep this simple because I have no intention of turning this new garage into a major workshop. It's just a storage building with an occasional maintenance function added.

I want this new circuit to be dependable and I'm concerned about voltage loss. Adding the distance from the panel in the house to where the new line will terminate at the new garage, it looks to be about 200 feet of 10 wire. Does anyone think I'll have a problem with this circuit? Most of the posts I've read seem to think I'll be all set but I'm not sure. I'm guessing the only real risk is tripping the breaker while using the miter saw under a load but it's hard to say for sure. Anyone have any better educated opinions? I'd appreciate your two cents.

 

[powerpace]

You need a sub panel in the new construction and I would go with at least three circuits. Lights, electrical outlets and one more at least for when you realize you didn't have enough. One should be a 20 Amp Circuit.
When you try to sell the property a inspector would ask about the subpanel if is not there and that would open a whole new can of worms. Not to mention insurance problems with self wiring not to Code.

 

[KennyG]

Doing it right won't cost much more in this case. Subpanels are pretty cheap. I usually overdo things and then am glad I did. The electricians here can double check me on this, but if you've got space in your main panel, I would add a 30 amp 220 circuit, run 10/3 all the way to the subpanel and then break off a 15 amp light circuit and multiple 20 amp outlet circuits. That way you would have 220 available in the event someone wants to use a air compressor or small welder there in the future.

 

[Mendonsy]

The line drop on #10 wire at 20 amps should be about 0.23 volts per 100' of wire. That amounts to less than a 1 volt difference.
Even so I suggest that you run bigger wire, maybe #8 (50 amps) or #6 (65 amps). There is not all that much difference in the cost of the wire and it gives you some options if you decide to do something different later on.

 

[pinetree10]

Thanks for your input. As far as the inspection comment, my research so far says that the code allows running just one line to a detached building as long as I include a basic means of disconnecting power inside the new garage, and a simple switch will suffice. Any problems with the code would arise if I ran more than one line because then I would need the sub panel. Thanks for the suggestions.

 

[DaveOmak]

Where I'm from, Romex can't be installed in conduit... 3 Single strands of 10 ga could be run.... the reason, Romex will not allow for heat dissipation inside conduit.... Just the code here.... check yours.... Then you would have the capability of 220 and 110 volt circuits... Something to think about.... I'm not sure if 10-2 romex will fit in 3/4" PVC conduit....

Dave

 

[DaveOmak]

Where I'm from, Romex can't be installed in conduit... 3 Single strands of 10 ga could be run.... the reason, Romex will not allow for heat dissipation inside conduit.... Just the code here.... check yours.... Then you would have the capability of 220 and 110 volt circuits... Something to think about.... I'm not sure if 10-2 romex will fit in 3/4" PVC conduit....

Dave

 

[pinetree10]

Where I'm from, Romex can't be installed in conduit... 3 Single strands of 10 ga could be run.... the reason, Romex will not allow for heat dissipation inside conduit.... Just the code here.... check yours.... Then you would have the capability of 220 and 110 volt circuits... Something to think about.... I'm not sure if 10-2 romex will fit in 3/4" PVC conduit....

Dave

If you read the original post I'm not installing Romex in conduit. The Romex will be inside each structure only.

 

[DaveOmak]

I'm glad you had that covered and were miles ahead of me..... So many times folks miss the details.... like I just did when I re read the original post.... Sorry about that...... Dave

 

[pinetree10]

If I were miles ahead of any of you I surely wouldn't be on here asking for advice. I don't blame anyone for missing details in my lengthy post. I don't disagree with anyone's ideas either. I just have to make sure I'm not shortchanging myself with the 10 wire so I won't have to worry about voltage drop. I'll let you guys know how I make out. Thanks for the suggestions.