Garage Electrical Service Run

[kest874]

Starting to plan out the electrical run to new detached garage (being built now).

Planning to run 2" conduit from the main panel on the side of the house. Have 2 choices, either run through the yard the entire way or through the crawl space for part of it.

There are 2 air conditioning units (marked red) on side of the house where the main panel is so I would have to go further out and come back.

I'll use MHF the entire way through conduit. Which is preferable?

If the conduit is in the crawl space should it be brought up and attached to the floor joists or can it be simply on grade?

There is a septic tank and leech fields I will need to avoid in the back yard.

I've attached pictures of bother options.

 

[alfredeneuman]

If the conduit is in the crawl space should it be brought up and attached to the floor joists or can it be simply on grade?

It's nearly impossible to strap the conduit to dirt, so it will have to be attached to the floor joists.
Be sure to not have more than 360° of bends between pulling points (boxes or conduit bodies)

 

[Innovate1]

You could switch to something that didn't need to be in conduit for the run under the house, attached to floor joists. 2" will make the pull easier. You didn't mention size of wire or amps but I am guessing it's 90A or less. A common way is to bring up the wire on the outside of the house to a pull box, could be an LB I think, and then run through the rim joist into the crawl space. If you go under the footing into the crawl space without a pull box you will end up with 360 of bends. I would think that's going to make the pulling much harder. Not sure it's to code (support distance on conduit) but you might consider using 45s to bring the conduit up to joist level. Don't know how much room you have in the crawl space but seems like doing pulling there would be a pain.

 

[larry4406]

I ran SER thru the attic to a junction box. From there I ran XHHW in 2” conduit. The advice I got here was that the XHHW would pull easier thru conduit than MHF would. I used Polaris type connectors at the junction box.

 

[kest874]

Looking to allow for 90amp service (future proof), if I transition to SER I need to do it twice as the main panel is on the exterior of the house. If I used an LB on both sides of the house and continue the conduit would it be easier to pull?

Assuming 2" conduit how big of a junction box would I need? Assume spice can not be in LB.

 

[kest874]

Another question assuming the run is 140' will Aluminum 2-2-2-4 allow for 90 amps.

I won't have AC other than maybe a window air conditioner, do not currently have a welder, but may in the future. I do have 240v 20amp table-saw, and regularly run air compressor (small 120v craftsman) and dust collector.

 

[Innovate1]

Looking to allow for 90amp service (future proof), if I transition to SER I need to do it twice as the main panel is on the exterior of the house. If I used an LB on both sides of the house and continue the conduit would it be easier to pull?

Assuming 2" conduit how big of a junction box would I need? Assume spice can not be in LB.

LBs on both sides of the house and conduit all the way sounds like a good plan to me. The run from garage to house will be two 90 bends will be much easier than four 90s. The run through the floor joist space will be a straight shot - easy. And then feed up to main panel. Avoids splices too. Even with you oversizing the conduit with 2" I wouldn't want to pull with four 90s.

 

[Innovate1]

Another question assuming the run is 140' will Aluminum 2-2-2-4 allow for 90 amps.

I won't have AC other than maybe a window air conditioner, do not currently have a welder, but may in the future. I do have 240v 20amp table-saw, and regularly run air compressor (small 120v craftsman) and dust collector.

For 240V the drop at 90A is 2.6%. NEC recommendation is 3% max so you are ok. If you have large 120V loads they should be balanced as much as possible but that should be standard practice.

 

[kest874]

For 240V the drop at 90A is 2.6%. NEC recommendation is 3% max so you are ok. If you have large 120V loads they should be balanced as much as possible but that should be standard practice.

Won't have much going at the same time, last attached garage I used a 20amp circuit for each outlet, total of 4 outlets, and never really used more than 2 at a time.

It's a 24' by 24' garage, not going to run a business in it either.

 

[kest874]

LBs on both sides of the house and conduit all the way sounds like a good plan to me. The run from garage to house will be two 90 bends will be much easier than four 90s. The run through the floor joist space will be a straight shot - easy. And then feed up to main panel. Avoids splices too. Even with you oversizing the conduit with 2" I wouldn't want to pull with four 90s.

Think this will be fine, I'll need an LB on the outside by the main panel as well since the panel is mounted externally.

I also have a sub panel in the existing garage that is closer but it needs a rework, and doesn't have any additional space in it. All house loads are on that sub panel.