New electrical circuit. Plastic conduit same as metal?

[atgcpaul]

I need to run a new circuit in my shop's subpanel for a new jointer/planer. I'm running the wire through surface mounted conduit. Are there times where I must use metal conduit over the plastic conduit?

Thanks,
Paul

[JTTHECLOCKMAN]

In a shop metal offers better protection. Nothing wrong with plastic as long as you run a ground with every run.

[Robert Adams]

JTTHECLOCKMAN said:

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In a shop metal offers better protection. Nothing wrong with plastic as long as you run a ground with every run.

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True but you also have to run a ground with metal as well. Been required since the 80s.

But a 1/2 bender is cheap and will make up the cost of buying pre-made 90s pretty fast.

[WaterlooMarc]

Robert Adams said:

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[blockquote]JTTHECLOCKMAN said:

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In a shop metal offers better protection. Nothing wrong with plastic as long as you run a ground with every run.

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True but you also have to run a ground with metal as well. Been required since the 80s.

But a 1/2 bender is cheap and will make up the cost of buying pre-made 90s pretty fast.

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[/blockquote]

I just got done running mine and agree with this. Those elbows are ridiculous! I ran two circuits in mine (12ga / 20amp) and didn't have a problem pulling the wire. I pre assembled and pulled the wire through the elbows before fixing the conduit though. Learned that from my last shop...

I went with metal based purely on aesthetics!

[A Squared]

Robert Adams said:

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True but you also have to run a ground with metal as well. Been required since the 80s.

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Are you sure about that? First off, I agree that it is good practice. In the few times I've run wiring in EMT, I've pulled a separate ground wire. But, this topic seems to come up pretty frequently on Code and Home improvement forums, and it always seems to me that the guys claiming metal conduit or EMT may be used for a grounding conductor are the ones who are able to support their position with code references.

Of course, local jurisdictions may have any manner of amendments to the NEC, but other than that, I think it may be legal under the unammended NEC.

[John Mihich]

My town requires metal conduit but not an extra ground.

Metal is really easy to deal with IMO. Doesn't take much to learn how to bend it. And of course metal is much more protective.

[TDKPE]

A Squared said:

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Of course, local jurisdictions may have any manner of amendments to the NEC, but other than that, I think it may be legal under the unammended NEC.

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2011 NEC 250.118 Types of Equipment Grounding Conductors. The equipment grounding conductor run with or enclosing the circuit conductors shall be one or more or a combination
of the following:
(1) A copper, aluminum, or copper-clad aluminum conductor. This conductor shall be solid or stranded; insulated, covered, or bare; and in the form of a wire or a busbar of any shape.
(2) Rigid metal conduit.
(3) Intermediate metal conduit.
(4) Electrical Metallic Tubing.
.
.
.
(14)

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[/blockquote]
But it's entirely possible, likely even, that local AHJ's have more stringent requirements, and a lot of electricians don't like using the conduit, as a break anywhere will break that continuity. Bang into a conduit near a connection with a forklift, and you can pop the joints. Not that I've ever done anything remotely like that almost four decades ago.

If you run only a single equipment grounding conductor for multiple circuits, it has to be sized for the highest ampacity circuit in the raceway.

NEC 250.122 Size of Equipment Grounding Conductors.
© Multiple Circuits. Where a single equipment grounding conductor is run with multiple circuits in the same raceway, cable, or cable tray, it shall be sized for the largest overcurrent device protecting conductors in the raceway, cable, or cable tray. Equipment grounding conductors installed in cable trays shall meet the minimum requirements of 392.10(B)(1)©.

[Anak]

For your shop, as long as you are above ground metal is the way to go. Plastic is the way to go if you are going underground.

[John Mihich]

I agree about a factory setting that a ground wire should be included. In a home shop - not so much of a big deal. Although I have seen conduit pulled apart in basements I have worked on.

[A Squared]

John Mihich said:

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I agree about a factory setting that a ground wire should be included. In a home shop - not so much of a big deal. Although I have seen conduit pulled apart in basements I have worked on.

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So you've seen yourself why it's not a good idea.