Running Line To Shed

72chevy4x4

I would like to run a line to couple of sheds-a line for the alarm system is absolutely necessary, but a 15A or 20A line for an outlet or security light would be great. The length is going to be pretty long-about 125' from the circuit breaker to the first shed and another about 150' to the second shed.

Is anyone aware of a direct burial cable for an alarm system (~20 gauge two conductor)?

What would you recommend for this situation? Can I direct bury UF12-2 and install as a 15A gfci (due to the length)? What depth?

If there is no direct burial alarm wire-would a run of 1/2" schedule 80 (or is it 40?) keep it dry in wet soil?

mdshunk

I have a quick minute... but bury conduit, brother. You'll thank me later. I'll reply in more detail in a while if nobody gets to it first.

72chevy4x4

thanks for the quick reply...for anyone else as well: can I run the 12-2 along side alarm sensor wire? I'm familiar with running cat5 cable-it shouldn't be run parallel to 120v-I would guess the alarm wire would be similar (unless it's DC). Would 3/4" pipe be large enough-or a little tight?

A.W.Davis

As what MD said.....save yoursef some problems down the road and use conduit.....condiut is cheap and either way you would be digging a trench to bury the wire regardless so might as well take a few extra steps and have piece of mind.

If you go with conduit (that would be my choice) you will want to be 18" below grade to the top of the conduit unless you are trenching near a driveway then you will want to be 24" deep and use schedule 80 conduit. EDIT: I ran stranded 1 gauge from one house to anothern so thats why it was so deep and in sch. 80 conduit I am not sure about schedule 80 and low voltage wire though, the inspector at my job passed me and I used sch 40 for the phone and cable raceways 24" below grade.

Remember also that by code you cannot go over the 360* limit on your conduit bends, so basically you are only allowed (4) 90* bends from start to finish

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72chevy4x4

re: the 360 degree code mentioned: I don't think it is an issue, but could that be circumvented by providing a junction box at the first shed, then a 'new' run of conduit (and the 360 degree limitation) from the first to the second shed?

This run of conduit will go beneath a driveway-after the 24" depth around the driveway, can it shallow up to 18"? I guess it would have to stay schedule 80 the whole way then?

Magnettica

I'd definitely go with the conduit. Probably a pair of 3/4" pvc. One for the line voltage, one for low voltage. Never put the two in the same conduit.

As far as digging and burying your pipe, you could go 12" deep as long the 120 volt circuit has GFCI protection. You could use either a GFCI circuit breaker, receptacle, or faceless device.

Good luck!

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Same Old

Electricians correct me if I'm wrong but can't you run it directly under a slab if it's in pvc conduit?

Magnettica

I just looked at Table 300.5 and as long as the slab isn't a building then it seems ok to me.

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GregS

You can run alarm wire with AC. The 4C alarm wire is just going to be providing 12V and then a loop for a switch. No signal induction to worry about. Just watch your length.

Run the conduit. And pull a couple of cat5e's in there too. You never know what you could use them for.

Magnettica

I don't think that's entirely correct. 725.26 (B)(1) says:

Class 1 circuits and power supply circuits shall be permitted to occupy the same cable, enclosure, or raceway only where the equipment powered is functionally associated.

My interpretation of that is the security light must be controlled by the alarm circuit otherwise it's a violation of 725.26 (B)(1).

And if that doesn't convince you, 725.55 (A) will.

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mdshunk

But not if you want your job to be code compliant.

Magnettica

MD, I was reading Mike Holt's Wiring Methods book earlier and there seems to be some grey area concerning running LV with HV in same conduit. I've come to understand that class 1, 2, and 3 should never be run with 120/240 volt lines but the wording for this is a bit questionable. I'm thinking that it might be permissable if the insulation for the class 1, 2, or 3 wiring is rated for the highest voltage in the conduit. Nonetheless, it seems shady to me. I would just run the seperate conduit and be done with it.

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travelers

with all these electricians here, kinda hard to believe nobody has mentioned voltage drop!! if i were you i would do 2 runs of schedule 40 pvc...stick them in the same ditch and try to keep 2 inches between them...bring them up into the first shed in seperate pvc boxes...when u come up it would be good to goto a schedule 80 riser into the boxes..then run to the second shed with 1 pipe from each box.

also do yourself a favor: use thhn 10 ga stranded wire...it's easier to pull plus with a 10 ga circuit, you shouldn't have voltage drop issues...generally if you go over 200 feet, then you have to upsize the wire because of a voltage drop..

mdshunk

That's because the electricians on this site know that voltage drop is not only dependant on the distance, but the connected load. He's mainly talking about running a light. Voltage drop will not be a concern with a connected load of that sort.

GregS

My mistake. I was comparing it to a non-conduit run, such as through an unfinished basement or other exposed area and suggesting that close proximity would not affect the purpose of the wire.

mdshunk

My apologies, then.

Magnettica

Good point. I had thought about the voltage drop but hadn't posted about it because of all the other issues being discussed. If the original poster is 125ft from the first shed, and the 2nd shed is 150ft from there, then he'll defintely need to be runnning #10 THHN/ THWN, with 'W' in THWN being the important part.

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72chevy4x4

thanks for the feedback guys. After talking w/ the alarm company and getting their input on this project, I did some research and found that a 10 gauge direct burial is made (I thought 12 gauge was all I had to choose from). The alarm guy (who designs systems) suggested a direct burial wire over running it in a conduit b/c of our wet soil conditions.

would the use of 10-2 UF be a suitable substitute for running conduit and THWN? When choosing to lay conduit w/ the THWN, what is the main reason you (electrician's) would choose this method over UF cable?

As a side note-I enjoy reading the electrician's forum b/c of the ongoing dicussions of the proper method to perform a function. It seems like a game at times-who can answer most quickly with the correct section of code

mdshunk

Direct burial cable has a lifespan. Direct buried cable will always fail. Conductors in conduit will too. It's so much easier to replace conductors in conduit. Replacing direct buried cable involves digging again. Direct bury is cheaper, but running the cable or conductors in conduit is "the right thing to do".

GregS

DB always fail? Due to deterioration of the jacket? Extreme corrosion of the conductors?

I'm curious because I deal with db telephone and TV cable copper for houses all the time and haven't really seen (or heard) of issues except when someone puts a shovel, or a backhoe (argh!) through them..

Is it different for electrical because of the amps?