Conduit size for wiring to garage

[75gmck25]

I have a detached garage that will require about 45 feet of buried cable to run electric for a sub-panel, and another run for low voltage cat 6 and coax lines. I plan to use a 60 amp breaker for the connection to my Square D QO main panel, since that seems to be sufficient for what I need. I could also use a 90 amp breaker, but that seems to up the breaker price significantly.

My power needs for the garage are moderate. I have a window A/C, small 120 volt compressor, lights, grinder, table saw, etc., and may buy a small welder in the near future. The only reason I can think of for needing as much as 90 amps is if I add an EV charger in the garage, which is not likely.

I have already run aluminum SER 2-2-2-4 from the main panel to the inside wall of the house nearest the garage, and now need to transition to MHF or THWN for the 45 foot underground run in conduit from the house to the garage.

I need to decide what cable to run underground, and what conduit size I need. Aluminum MHF in 2-2-4-6 and 2-2-2-4 are available by the foot for a reasonable price, or I could run separate THWN wire. However aluminum MHF seems likes the easiest and cheapest choice.

If I run MHF, is 2" conduit large enough to easily pull about 50 feet? It will come out of the house wall, turn 90 degrees down, then another 90 to go straight out into the trench, and then two more 90's to come out of the trench and into the side of the garage. I will have a another junction box there to transition from MHF back to SER, since its my understanding that I can't run MHF within the structure.

For the low voltage run of a coax cable and two Cat 6 cables, what would you recommend for conduit size? It seems like 1 1/2" is large enough, but I'm not sure how well multiple low voltages cable will pull (do they bind on each other?).

Thanks,

Bruce

 

[sberry]

Yes, 2 will go easily in 2 inch. It will go in 1 1/2 but 2 is a lot better.

 

[kd3pc]

f I run MHF, is 2" conduit large enough to easily pull about 50 feet? It will come out of the house wall, turn 90 degrees down, then another 90 to go straight out into the trench, and then two more 90's to come out of the trench and into the side of the garage. I will have a another junction box there to transition from MHF back to SER, since its my understanding that I can't run MHF within the structure.

In apprentice school..that would be 4 90's....and that is all but impossible to pull, machine or not.. YOU will need LBs on either end and pull the bottom piece with enough slack to feed the LBs

2" is not enough to pull "easily" MHF unless you soap/snot the thing and have some help pulling and feeding..

bests, others will chime in and my JATC was 35 years ago....

 

[sberry]

I did number 2 with 4 turns in 1 1/2 dry with push and pull, it goes. I pulled some out a while back, that was a problem due to the fact that you couldn't push. We tied a rag on with a little juice when we pulled it and one ahead when we put it back, it didn't take a lot and it helped a little. These were 100 foot runs.
It will go 2 easy. Put a rag ahead and a cup of lube or so. Enough to get it to glide a little thru the first couple turns. We did 4 of them at 100 ft each and still had a little left from a quart.

 

[matt_i]

Its just my own opinion but I would not want to splice conductors via Jbox in the middle of a sub panel feeder run. I would have attempted to run the conduit the entire way from main to sub, put in "C" bodies where needed, and pulled the wires in, unbroken. I would also keep conduit bodies from being buried underground, either LBs above ground or use sweeps underground. Again you are getting my own personal opinion here.

 

[wyliesdiesels]

.........I need to decide what cable to run underground, and what conduit size I need. Aluminum MHF in 2-2-4-6 and 2-2-2-4 are available by the foot for a reasonable price, or I could run separate THWN wire. However aluminum MHF seems likes the easiest and cheapest choice.

If I run MHF, is 2" conduit large enough to easily pull about 50 feet? It will come out of the house wall, turn 90 degrees down, then another 90 to go straight out into the trench, and then two more 90's to come out of the trench and into the side of the garage. I will have a another junction box there to transition from MHF back to SER, since its my understanding that I can't run MHF within the structure.

For the low voltage run of a coax cable and two Cat 6 cables, what would you recommend for conduit size? It seems like 1 1/2" is large enough, but I'm not sure how well multiple low voltages cable will pull (do they bind on each other?).

Thanks,

Bruce

As said above, I would run MHF panel to panel if you can.

Yes MHF can be ran inside but MUST be inside conduit when indoors.

MHF will be the cheapest option.

yes 2" conduit will work fine for that.

1 1/2" for the low voltage will be fine though i would run (2) 1 1/2" conduits so you have a backup.

..........In apprentice school..that would be 4 90's....and that is all but impossible to pull, machine or not.. YOU will need LBs on either end and pull the bottom piece with enough slack to feed the LBs

2" is not enough to pull "easily" MHF unless you soap/snot the thing and have some help pulling and feeding..

bests, others will chime in and my JATC was 35 years ago....

Ive pulled 4 wire #2 AL in 2" conduit at lengths longer than that without any issue. It wasnt impossible or hard.

Code allows 360* of bends before a pulling body is needed to reset the count.

1 1/4" IIRCC is the min for #2 MHF so 2" is more than enough.

 

[sberry]

Just curious, what would one need a backup conduit for? How many customers pay to put extra pipe in the ground? The only time I needed extra stuff was for changes and the pipe didn't go there anyway.

 

[75gmck25]

Thanks for all the input.

I didn't mention it, but assume I will use LBs to make the 90 degree turns where the vertical conduit turns and goes in and out of the the wall, and a wide sweep 90 to make the underground 90 degree turn.

Using a continuous run of MHF in conduit all the way into the sub-panel also makes sense, since I need to run conduit in the garage anyway (brick walls).

The conduit will come up from below, which makes it easiest to feed it into the bottom of the sub-panel. I plan to use a QO panel similar to this one, although I don't need that many circuits.
http://www.homedepot.com/p/Square-D...-Load-Center-with-Cover-QO124M100PC/204844624

The inside of this panel can be rotated to put the main breaker at the bottom for easier connection, but my OCD side prefers to have the main breaker at the top. Is there any reason I can't feed the MHF in the bottom and still connect it to a main breaker mounted at the top? I don't know how flexible the wire is, and/or how difficult it will be to get it connected from a bottom feed into a main breaker at the top.

Thanks again,

Bruce