Outside Runs

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Old 09-16-06, 06:59 PM
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Outside Runs

I want to add a run from my service to my garage. Easiest way is to do it with an outside run as follows (then comes the question!):

Service box down to and underneath covered deck floor

Exit covered deck floor at house corner, then 90-degree ell, then 30-foot run outside house, then 90-degree ell into garage.

30-foot run is exposed to elements.

Questions:

1. What kind of pipe and fittings must I use - thinwall? PVC?

2. How high must the horizontal run be from the ground, or can it be near ground level?

3. What is best type of fastener to use on outside run - it will be going along brick the entire length?

I live in Colorado.
 
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Old 09-16-06, 07:13 PM
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Questions:

1. What kind of pipe and fittings must I use - thinwall? PVC?

2. How high must the horizontal run be from the ground, or can it be near ground level?

3. What is best type of fastener to use on outside run - it will be going along brick the entire length?##

1)If this along a garden wall,back yard and NOT adjacent to a drive way, Schedule 40 (sc 80 for driveway) Pvc would be fine.I would recomend 2-hole clips at no less than 5' (min,to prevent sagging) apart.

2) again driveway? Keep it at the sill level.If not, any height is good.

3)1/4" plastic anchors are fine for this application. You will need a masonary bit and a hammer drill.

90s' inside or outside? sweeps are ok, some situations an "LB" fitting would be better.
 
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Old 09-17-06, 05:59 AM
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Another consideration...
PVC expands and contracts a good deal so using PVC conduit for long outside runs requires expansion joints in stragetic places.
352.44 in the NEC covers when they are required.
I like PVC and use a lot of it, but it needs to be installed correctly so that it can grow and shrink as the (seasons) temperature changes.
I imagine that in Colorado it wouldn't be unusual to see a termperature swing of 100 degrees (F) between winter and summer. At that difference a 100 foot run of PVC conduit would expand (or contract) a little over 4". A 50 foot run would expand half that much. So you see, if you attach it so that it can't move freely, something will bow or break.
The straps that you use should allow movement of the pipe.
In a local jurisdiction near where I live the AHJ (the man) allows the use of one size larger straps when securing PVC. A example would be using 1 1/4" two hole straps on 1" conduit.
steve
 
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Old 09-17-06, 02:34 PM
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This has been an issue here for years. I have still to find the wire expantion coupling though.
Pipe moves but wires don't? I do have a wire stretcher, but I refuse to leave it on the job!
 
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Old 09-18-06, 06:53 AM
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I know what you mean.
You can (normally) get 2" expansion couplings at the "Big Orange Store", I saw some there last week.
Most big electrical supply houses carry various sizes, although if you just walk in off the street and buy one, look out, they're gonna get your money.
In my opinion it's possible to install (most) pvc conduit in a way that allows for thermal expansion and doesn't require expansion couplings. Things like using oversize straps, and not securing the pipe as close to the elbows. If you calculate what the expansion will be and make provision in your installation so the pipe can move that amount without getting in a bind, it will be OK. I always give any pvc conduit system that I install a good shake before I pull the wire, you should get a good rattle if it's "free" enough.
Like you, I've often wondered how the pvc expands and the wire doesn't (as much anyway).
Expansion is not a consideration (for pvc conduit) if it's calculated at less than 1/4" in straight runs between fixed points. AT 100 degree (F) temperature difference, pvc conduit will expand .04" per foot. So, (Per the NEC) a length of pvc conduit that's over 6' long between fixed poionts requires a expansion joint.
steve
 
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Old 09-19-06, 07:03 PM
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Good tip, one that I never wooda thunka.

The horizontal run will be 20 to 30 feet max, so I'll look for something at you -know-who's.
 
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Old 09-19-06, 07:05 PM
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Adjacent to the wall that will have the run is a concrete RV parking slab.

Just so I don't misunderstand, by "sill", do you mean window sill or do you mean the sill plate at the bottom of the wall?
 
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