When to use conduit?


Old 02-06-06, 05:08 PM
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When to use conduit?


I am currently in 'planning mode' on the rewiring on my 1900 Oregon home. Currently wired fully K/T with a few exceptions (lighting circuits are currently exposed K/T in attic with blown insulation).

My current question is about the usage of conduit. I have studied 'Wiring Simplified' and some other less-heady works without finding a satisfactory answer.

When is conduit required, and when can I just run bare cable? Is it required in any run over a certain length, or in certain locations?

I will be running some circuits up into our attic (unfinished, full-height, covers 80% of house), and some down through our crawlspace (30" vertical clearance, mostly moisture barrier covering a slab). The service panel is located in an attached workshop at one corner of the house, so some runs will be long-ish.

Currently all wiring is fully exposed (no boring through joists or anything, just strapped on top/underneath). It is a complete mess and while almost anything would be an upgrade, I am very concerned with doing this right the first time.

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Old 02-06-06, 05:36 PM
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Join Date: Jan 2006
Location: Greenville, SC
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Conduit is really only used in an area where the wire might be damaged.
I have never seen anyone wiring a house using conduit. We however use it only when wiring up HVAC units. And only where it runs to the outside to the unit and to the disconnect box. Hope this helps.
Old 02-06-06, 05:37 PM
Join Date: Sep 2000
Location: United States
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Unless you live in one of the few cities in the U.S. that requires conduit everywhere, you probably need it nowhere. The only time you would consider conduit is if you plan to run wiring on the surface of a wall somewhere, or someplace else where it would be subject to physical damage.

Wiring Simplified covers attic wiring very well. The rules require guard strips in certain situations depending on what kind of access you have to the attic and how far the wiring is from the opening. The book provides the details.

Read every single word in the Wiring Simplified book twice, except perhaps the chapter on farm wiring.
Old 02-06-06, 06:43 PM
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Location: PA
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some more reasons to use conduit

Conduit is useful when running wires of a gauge or combination for which a ready made cable is unavailable, not readily available, or more expensive than the sum of its constituent parts plus cost to assemble.

Conduit is also useful for telephone, TV, and computer lines with planned obsolescence that you might want to replace from time to time without opening your walls.

Metal conduit is necessary in many commercial buildings, multi-family dwellings, and employer supplied housing.
Old 02-06-06, 06:59 PM
Join Date: Nov 2004
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Originally Posted by bolide
Conduit is useful when running wires of a gauge or combination for which a ready made cable is unavailable, not readily available, or more expensive than the sum of its constituent parts plus cost to assemble.

An example of that was when I needed 15' of either 12-4wg or 12-2-2wg Romex for a unusual situation I was wiring at my house. I called around and found it was only available locally in a 250' roll (may have even been 500'). I ran conduit and pulled individual conductors.
Old 02-06-06, 07:50 PM
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Ok, this information helps a lot. My plan to date has no special needs so it looks like I won't be needing any conduit (not required in my area). I was also curious if it was considered to be a 'better way' to run cable, but it doesn't appear to be.

John, I had read that section on straps and guard strips a few times, though I will probably just bore through joists and run everything that way, parallel as much as possible. There is a possibility in the future of us finishing the attic and I'd like to run cable 'out of the way' now so it wouldn't be an obstacle in the future.

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