Questions on trenching/conduit..

[nperkins]

I'm getting ready to run my electrical for my garage (Or at least get the conduit run to save me $$)... Its about 40 feet from the edge of the house to where I'd like the electrical to go... I have a few questions.

#1. I'm planning on running a 50 amp, possibly 60 amp service to the garage.. Will a 2" piece of conduit work?

#2. I'm also planning on running 2 Cat5 cables (For redundancy) out to the garage for internet purposes.. Thinking 1" pipe? And can I run them directly next to each other? Or do they need space in between them to prevent cracking/breaking?

#3. I've been debating if I want to do running water... But then that means an entirely separate trench, that has to be 48" underground vs 24" for the electrical, right?

#4. if electrical has to go down 24", why do all the damn trenchers I can rent only go 18" ?? I'm assuming just shovel down the last 6"?

#5. Do I need to put any sand/fill in the trench before the pipes?

 

[A_Pmech]

1) Yes.

2) 1" conduit would be fine. Pull them in at the same time so they don't chafe.

3) That depends on your local frost depth. The water line has to be beneath the frost line or you run the risk of it freezing.

4) Small chain-type trenchers go a lot deeper than 18". You don't want to shovel that last 6".

5) If you have rocky soil then yes. Otherwise no.

 

[nperkins]

3) That depends on your local frost depth. The water line has to be beneath the frost line or you run the risk of it freezing.

4) Small chain-type trenchers go a lot deeper than 18". You don't want to shovel that last 6".

I meant more to be "at code".. Like if I decide to use a backhoe instead of a trencher, can I dig down 48", bury water line, cover it up to 24", run the electrical? Or would i have to say, dig a trench for electrical, then say 2' left or right of the electrical trench dig another one.


And the chain trenchers I see for rent at home depot all say 18"... Do they actually go deeper?

 

[A_Pmech]

The one trench thing is something to take up with your building inspector. Some allow it, others don't.

Try your local rental yard. They should rent chain trenchers that go at least 36" deep.

 

[rlitman]

The one trench thing is something to take up with your building inspector. Some allow it, others don't.

Agreed, though I've only seen horizontal separation required on gas pipes (two feet IIRC, but don't hold me to that), or on separating water from sewer (some real distance for this one).

2a was not answered. They can be right next to each other.

Regarding #4, the required depth for PVC conduit is most likely 18", not 24", unless you're going under a street, highway, road, etc.
24" is for direct burial wire, not conduit. If you're using RMC conduit, you could get away with 6". PVC conduit is ok at 12" if it is for a single circuit that is GFCI protected. Refer to NEC table 300.5 (A)

 

[nperkins]

Agreed, though I've only seen horizontal separation required on gas pipes (two feet IIRC, but don't hold me to that), or on separating water from sewer (some real distance for this one).

2a was not answered. They can be right next to each other.

Regarding #4, the required depth for PVC conduit is most likely 18", not 24", unless you're going under a street, highway, road, etc.
24" is for direct burial wire, not conduit. If you're using RMC conduit, you could get away with 6". PVC conduit is ok at 12" if it is for a single circuit that is GFCI protected. Refer to NEC table 300.5 (A)

I had been chatting with a local electrician who had told me 24" was the depth... The shed that was in the location that the garage is going simply had 14/2 romex buried about 12" down... No conduit, no nothing... And was actually tied into the same circuit as my furnace, washing machine, and part of my living room. So I'm basically trying to re-run it properly... No need for inspector if you catch my drift. (And yes, the furnace is rewired onto its own circuit already). I do plan on running a sub panel in the garage as well.

I was planning on running both conduits using Schedule 40. Is that okay or should I pay the little extra for Schedule 80?

 

[HotwheelsYJ]

If no permits are involved, dig the trench to below frost line for your area. Put water & conduit for low voltage stuff together in the bottom of the trench. Throw in about a foot of dirt & put in your main feed conduit.

Cover it up. Seed some grass & call it done.

Sch40 is fine underground. You only need sch80 where it comes out of the ground.

 

[alfredeneuman]

If no permits are involved, dig the trench to below frost line for your area.

Doing it right has nothing to do with whether it will be inspected or not.

 

[CNGsaves]

+1 for Doing It Once . . . Doing It Right.

Two trenches might cover EVERYTHING you could ever need in garage:

A) 1st trench 36" depth with 2" electric conduit at bottom in sand, then 12" backfill and low voltage 1 1/2" conduit (ie at 24" depth) containing RG6 and CAT 5e/6 cables (handle any TV, internet, security, phone, etc . . . plus extra pull string in there). Put in red caution tape after little backfill.

B) 2nd trench [couple feet over] below frost line (say 48" for discussion - - - OP need to have your LOCATION updated in GJ Profile) with your water line. If severe cold area, install pipe insulation also. Then backfill 12" and put in yellow plastic polyethylene pipe for natural gas at 36" depth (with tracer wire around the yellow plastic pipe). This is assuming your AHJ will allow this shared trench. Then 12" backfill and put in yellow caution tape.

 

[nperkins]

Thanks CNG... That was basically what I was looking for. Although I'll skip the RG6. I cut the cord five years ago lol. Will definitely be running an extra string though.

My only wonder about the water (I updated my profile btw), is that my slab is already poured... How do I get the water into my garage? Do I have to drill through the concrete and go down 48" ? I assume I can't run it up right next to the foundation then in, because then I'll have a freeze point, no?

Totally forgot about gas though... I was also debating running a propane line from house to garage (House stove uses lp, and garage will have an LP heater, so I figure one propane source would be nice), and possibly heating oil line as well so I can move my oil tank out to where the garage is and away from the house (Its an outside tank).