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.

 

[buickanddeere]

Not saving anything running 10/2. You will dislike the lights going dim and bright when tools start.
Run 10/4 out to the building and a 30amp breaker panel.
Ground rod at the panel and float the neutral . No bond between neutral and ground.
The difference in $$$ is minimal.
I'm tired of listening to cheapskates later crying they wish the job had not been overly economized.

 

[Qapla]

I am not an electrician or electrical engineer and will not claim to be up-to-date with all the current codes ... what I will share is that our well pump, a 4" submersible 1 HP, has been down there running fine for nearly 40 years connected to a 400' run of UF Buriable 10/2 with ground.

During this time we have had to replace the pump twice. Once when it was struck by lightning and another time when the foot valve went bad an sent pieces of metal into the pump. Neither of these problems had anything to do with the 400' wire run.

 

[buickanddeere]

Electric motor engineers know where pumps are often installed. Somewhere that 175V while starting and 200V while running can be expected. The well motors are designed to run at voltages that would smoke a shop air compressor motor.

 

[Iowachild]

For the pole building I just had built, I am running 4 #6 AWG copper wires in 1-1/4" PVC conduit to a 8 circuit sub-panel with a 50A main. It is not cheap, but it should meet anything I might want to run in the building in the future. I would consider the 30A sub-panel the minimum. :2cents:

 

[grsthegreat]

back to original thread....what you are planing to do is 100% legal. With only 1 (or 2) circuits going to an outbuilding you dont need a subpanel. But you do need a toggle switch as the first box after it enters the new shed as a disconnecting means.

good luck and have fun. The GFCI breaker will protect the new shop/storage area

 

[pinetree10]

back to original thread....what you are planing to do is 100% legal. With only 1 (or 2) circuits going to an outbuilding you dont need a subpanel. But you do need a toggle switch as the first box after it enters the new shed as a disconnecting means.

good luck and have fun. The GFCI breaker will protect the new shop/storage area

Thank you. I have planned to include the simple switch right after power enters the new building. I can completely understand anyone suggesting that I put a sub panel out there for future expansion. I am actually one of those guys who likes to overdo things because I just like high-end things and projects. The quality construction of the garage is testament to that attitude. That being said, my vision for this building involves little more than storing everything that used to be in my attached garage and doing some minor maintenance on all my equipment. Beyond the fluorescent lights, bench grinder and garage door opener, I don't see the receptacles getting much of a workout. Once again thanks for the feedback.

 

[aczlan]

I would still put in a breaker panel. $14 will get you a 2 space panel ( Shop Square D 4-Circuit 2-Space 70-Amp Main Lug Load Center at Lowes.com ) which can be wired for 120 fairly easily and another $8ish will get you a pair of breakers for it ( Shop Square D Homeline 20-Amp Single-Pole Circuit Breaker at Lowes.com ).

Aaron Z

 

[Raspy]

Aaron has it right.

Why work so hard to just get by and work around the code?

I think you can pull three insulated #8s out to this sub panel, drive a ground rod and be all set with a 15 amp lighting circuit and a 20 amp plug. Simple, safe, provides two disconnects and you could have 220v if you wanted it later. You could also have two plug circuits if needed. You can work on the plug circuit with your lights turned on and you'll have the lights on a proper circuit. Plus the circuits would be out of phase to help prevent dimming when a motor starts.

If you plan to use 10-2 romex and strip it first, you'll still be buying a third wire you don't need, the ground wire in the romex. The grounding should be done with a ground rod. #8 is a better choice with over 200' of run and three insulated conductors will give you options.

Or you could go with the absolute simplest method, as you've described. 10-2 with ground and a switch at the entry point.

 

[pinetree10]

Figured I'd update my original post in case anyone out there is tackling a similar project -

I went with my original plan, ran 10-2 Romex from a 20 amp GFCI breaker at the house panel to the outside, then changed over to #10 stranded wire in conduit to the detached garage, then changed to 12-2 Romex inside the detached garage. I'm glad I went with 10 wire because I didn't want more than minimal voltage drop. Where it entered the building I used a heavier duty single pole switch as the disconnect as code requires and then installed 4-foot T8 lights, a ceiling fan, and 8 receptacles, including one for the garage door opener and one for an overhead cord reel. The lights are great and work very well even in very cold NY temperatures. Haven't had any problems with dimming or tripping the breaker but I rarely come anywhere close to putting the circuit to the test, mostly running a little space heater to take the chill out and maybe occasional use of a compound miter saw or bench grinder. There's not a lot of simultaneous device use other than lights and one plug at a time so the single circuit suits my needs. My biggest complaint is the T8 ballasts destroy the music coming out of my FM radio but I knew that going into it so not a big deal. It's worth it because they're better in the cold and much quieter than the T12 high outputs I used to have in my attached garage years ago.

The building is basically a large storage shed that I also use for short periods of equipment maintenance so this works for me. I do agree with the other posters however, for anyone considering using a building like mine for extended periods during colder months, install a larger circuit with a small panel and if using electric heat install a 240 volt heater to take the chill out faster. I installed a Dayton model in my insulated attached garage because I still change my own oil and that thing raises the temperature about one degree per minute during even the coldest months of the year. It also makes my electric meter spin three times faster when it's running.

Thanks for the advice. Lots of good information on this site.

 

[Halftrack]

You might consider LED replacement bulbs for the T8s. I used FEIT T4819-LEDIF-41K, which are direct wire to 120v (bulb has pigtail) and do away with the ballast. Much more output and no interference.