Running Power to Detached Garage

[Pettrix]

On a future house/detached garage build. The main power will come underground (PVC electrical conduit) to the house panel which has to be placed outside (per code). For my detached garage, I would just run another conduit line with Romex from the house panel, back underground to the garage and bring the line under the slab or through the garage wall?

Should I have another sub panel inside the garage or just use the main house panel and connect the Romex lines to that?

 

[Midniteoyl]

Main panel feeding a sub panel.

 

[MossRoad]

It depends. For example, where I live, you are allowed to run 1 circuit to an outbuilding from the main building. So if you only want lights, a garage door opener, and a few outlets, one 20 amp circuit would be fine.

If, however, you want more than 1 circuit, you are required to install a sub-panel at the garage. That's still technically running 1 circuit from the main building to the out building. It's just a large enough circuit to split it out into smaller circuits at the sub-panel.

The reason for this is they don't want multiple electrical paths between the buildings.

So, best to check with your local building department to make sure what you want to do is up to their codes.

 

[Diggin It]

And beyond all that, no to Romex. THHN, UF maybe. I ran 12/2 w/ground UF but I will be replacing someday with 10/2, maybe 10/3 if prices ever get back close to sanity. Couple bucks a foot ain't a happenin'.

 

[ponytug]

Technically, you run wire in the conduit, not romex. (Heat buildup issues.)

If it were me, I would run pretty heavy gauge wire over to the garage to accommodate future uses like power tools, freezer, air compressor, welder... even if you don't use it, the next owner might. I would also consider that there might have an electric vehicle in the garage's future, which might take 40-80Amps. Even if you don't pull big enough wires for that, I would put in the conduit for all of that demand today. Conduit cost is trivial compared to everything else, and retrenching is a pain.

Just free advice...

All the best,

Peter

 

[Diggin It]

On a future house/detached garage build.

I just caught that. I'd run at LEAST 1" PVC, maybe 1 - 1/2"

That will allow much larger wire gauges, like maybe 8 or 6.

 

[Dwellonroof]

I would also run at least a cat5e wire for internet

 

[Diggin It]

Well, yes, I'd also be running at least two additional conduits not less than 3/4" for future use like data, phone, cable TV, etc.

 

[gary49]

I‘m getting more and more calls from customers about wiring for electric car chargers. I would recommend a minimum of 1 1/4” PVC conduit between the main panel and the garage. That allows you to install conductors for a 100 amp service.

 

[EddieWalker]

... to the house panel which has to be placed outside (per code).

Why is it Code to put the panel outside the house?

 

[Pettrix]

Why is it Code to put the panel outside the house?

The fire department must be able to access the panel to shut down power and circuits. You can put a padlock on it but of course, they would just cut it in an emergency.

 

[Diggin It]

But they don't need the whole panel outside to do that. All they need is Service Disconnect switch/breaker.

Meter >>> SDS >>> Main panel.

 

[3Ts]

I would also run at least a cat5e wire for internet

But not in the same conduit as the power cable.
I would go with cat6e and I'd use underground cat6e in the conduit. The underground cable has a gel inside the jacket to prevent water intrusion and the conduit WILL fill up with water (unless, maybe, you live in a desert). I would also go with conduit even with direct bury cable. It is easier to repair the cable if needed and better protects the cable against damage from digging or critters.

 

[RickB]

But they don't need the whole panel outside to do that. All they need is Service Disconnect switch/breaker.

Meter >>> SDS >>> Main panel.

Yank the meter head and the power is off.

 

[plowhog]

But they don't need the whole panel outside to do that. All they need is Service Disconnect switch/breaker.

A falling tree/limb hit the incoming power on two different friend's houses. Each time it ripped the weatherhead and panel off the wall. Better to have that stuff sparking outside than in.

 

[plowhog]

The cost of conduit and boxes is so small compared to trenching and backfill that I'd put everything in up front. Larger electrical PVC conduit for main power service, smaller for CAT 5/6 or alarm system, etc. I'd also put 1" water schedule 40 PVC even if you think you will never, never, never need it.

Funny how sometimes down the road you do need it. I'd terminate everything with boxes on each end so you could pull future wires through in case you think of something new.

 

[MossRoad]

But they don't need the whole panel outside to do that. All they need is Service Disconnect switch/breaker.

Meter >>> SDS >>> Main panel.

If you have meter > disconnect > panel, the service disconnect is considered the main and everything else after that is considered a sub-panel, and the neutral and grounds have to be isolated.

 

[4570Man]

How far apart is the shop from the house? I’d run a 100 amp circuit. You can buy 100 amp aluminum for about the same price ( edit that used to be true, but it looks like the copper is more than twice as expensive now) as 6 gauge copper that’s only good for half the load.

 

[4570Man]

The cost of conduit and boxes is so small compared to trenching and backfill that I'd put everything in up front. Larger electrical PVC conduit for main power service, smaller for CAT 5/6 or alarm system, etc. I'd also put 1" water schedule 40 PVC even if you think you will never, never, never need it.

Funny how sometimes down the road you do need it. I'd terminate everything with boxes on each end so you could pull future wires through in case you think of something new.

Have you priced conduit lately? It’s not exactly what I would call insignificant.

 

[plowhog]

Have you priced conduit lately. It’s not exactly what I would call insignificant.

I confess I have not priced conduit lately. So I have no clue on the cost of that. But I will know this summer ... I have a few thousand feet to run .... yikes!

But I still say that from one building to another, not a huge distance, any cost for conduit is cheap compared to trenching and backfill. YMMV.