Finally going to run power to the in-laws new detached garage. Existing conduit is 1 1/4″. Garage has exposed rebar for the separate ground. Going to pull 3 4gauge and 4 14gauge. 4 gauge is for 50 or 60 amp 220, the 14 gauge is to tie in and become a three-way with the outside house light. 4th 14gauge is the ground.
Total pull is about 115′. I’ve already fished a pull cord through, 1/4″ poly line. Can my FIL and I pull this? I was figuring on conduit/cable lube, how much do you think I’ll need?
Friend tells me he thinks I need to have two circuit breakers – one at the main and one in the sub-panel. T/F? Then do I need a separate shut-off in the garage, as in a lever that one pushes up or down?
Any thoughts appreciated.
Replies
My FIL is larger than Jerome Bettis, he could pull it. What's you FIL look like?
You need a larger ground wire.
Don't have time to look the size.
For service to a detached building you can go with a 3 wire supply ONLY IF there are no other metallic connections between the 2 buildings.
But you have metallic connections in terms of the #14 wire.
You still need the local grounding electrode at the garage.
Also you only need #6 wire for the load and length of run.
You need a breaker at the main panel to protect the feeder and sub-panel.
The garage needs a main disconnect. That can be just a switch, but most often it is the main breaker in the sub-panel.
And you migth want to use a 100 amp sub-panel as you can get them with many more slots than a 60 amp panel and they are common and inexpensive.
Thanks Bill,
By garage light I meant an exterior garage light. Sorry for the confusion. I intended to add the exterior garage light on with the house light and convert the existing house light and switch to a 3-way setup. Thus the exterior garage light, ext. switch, and ext. ground are part of the house wiring. All other garage lights/circuits will be part of the garage sub-panel. Does that solve the metallic connection problem? Garage panel will be grounded only at the embedded rebar, which I can only assume has 20' of continuious embeddment. (I think that's the code min. for grounding a panel)
I thought I would run 4gauge for any future loads that might exdeed 50 or 60 amps. I think, based on the conduit size, 4gauge is the largest I can run, which maxes out around 80 amps over that distance (115'). But the 100 amp panel is a good idea.
You've given me electrical advice and I respect your knowledge. Thanks
There are a couple of different reasons for a "ground".One is a return path for an external discharges; ie lighting.The other is the equipment grounding conductor, which serves 2 purpose.One is to a return path for an fault currents in equipment. The other is to bond everything that might be energized so that it is all at the same potentinal. ie; you won't get a shock toching a refigerator (grounded via the egc adn the grounding receptacle) and the faucet bonded to the grounding electrode system.If the detached building is completely isolated from the house them it does not need to be referenced (grounded) to the house.But if you have a metalic path between them then they need to be bonded to the same grounding systme and thus the 3rd wire. Metallic pathes include water line, telephone, and cable.Now the garage ligth will not be in the same area as the garage wiring so that is not a problem by it'self. But if I understand correctly you will have a 3 way switch in the garage that will be refrenced to the house wiring grounds. However, this is an area that is up to the inpsector, if it is a permitted & inspected job. I believe that some areas allows require a 4 wire supply.
I would get this permitted and inspected, so I'll clear it up with my inspectors whether I need to run a 4th 4gauge as an EGC.
The exterior garage light wiring will be in the same area as the garage wiring; it will share the conduit to the garage, in the sub-panel the 3-way light THWN will be wire-nutted to NM, and then the various NM's will leave the sub-panel.
Assuming no other metallic paths, in your personal opinion, would these two buildings be isolated? Local jurisdiction trumps all, but just curious what you would say.
Thanks.
There is a high likelyhood that you would have the 3-way switch in the same box and common cover plate with a switch for interior lights. In my opinion that would make it a metallic path.If you only had an exterior light with no local switch you might convince the inspector that you don't have a common path.BTW, you only need one EGC. And I think taht it can be a #8, but I need to look that up and don't have time to do it.
You're right - I would have put the ext 3-way and the local overhead in the same box. Thanks for your opinion. I can look it the EGC requirements. I often use the Code Check Electrical as a resource. Can do one more question for me? What's the difference between the Code Check charts for wire fill: one is for 30% and the other is for 41% I believe.
I'm certainly no electrician, but wouldn't it be easier to run only the main power feeds to the garage and use one of the X10 type controllers to handle the lights?
I'm building my detached garage now, and that's what I was planning.
My parents and my sister live next to each other, and can control the outside lights on a couple different outbuildings from either house, with no complicated wiring.
I used one of the wireless versions to add a switch for my basement light - works great, installed in a few minutes, and cost about $10. The new switch just sticks on the wall wherever I want it.
My uncle, who is an electrician, has a number of outbuildings - sheds, barns, etc. He must have 20 switches by the front door of the house - all installed as 3-way switches before the X10 controllers became available. Now he would have used the X10's.
Don
I've used X10 before. They have problems about 10% of the time, impossible to troubleshoot. And I don't really like their switches.
Is running the hard wire a lot more work? Guaranteed. Sound crazy? Certifiable. But once I get in the attic and check out how crazy and how much more work it is, then I'll have our answer.
If you have 2 wires in the conduit you are limited to 31% fill, but for 3 or more then you can go to 40% fill.And for only 1 wire, 53%.I have no idea what the logic is behind those numbers.
Thanks again for all your answers, Bill. Logic behind those numbers? I can't see any in front of them either.
Last questions: Am I good with a breaker at the main and a disconnect lever in a separate box just before the sub? Or would you use a second circuit breaker in the sub?
"Last questions: Am I good with a breaker at the main and a disconnect lever in a separate box just before the sub? Or would you use a second circuit breaker in the sub?"Either will work, but the separate switch is probably much more expensive.
I was just wondering where in the Code does "The garage needs a main disconnect. That can be just a switch, but most often it is the main breaker in the sub-panel."?
~Peter
the reference are to the 99 NEC.Article 225, part B More than one building or other structure.225-31 Reuqire a method of disconnecting all ungrounded conductors that supply or pass throught the building or structure.225-32 requires it to be outside or immediately inside where the feeders enter that building.
cable lube. I pulled four wire through 2 inch pipe with two 90 and two 45. I used about a gallon and a half. it was worth every penny. strip back about a foot of copper, twist togather with the rope and wrap with tape. It will take two people. one to pull and one to feed