3/8" black pipe as conduit

[AZElectrical]

I have a project installing 277V light fixtures designed for mounting with a 3/8" stem. The installing contractor has suggested using 3/8" black pipe as conduit from a j-box on the ceiling, citing difficulty in obtaining 3/8" EMT. I believe black pipe typically has an oily compound applied on the interior and exterior surfaces to prevent rust. I haven't been able to find any documentation indicating that the 3/8" pipe is listed for use as conduit, so I'm hoping to get some input on whether or not this would be a 2011 code-legal installation. Would the compound inside the 3/8" pipe be safe to have in contact with standard THHN wire?

Thanks

 

[Joethemechanic]

If you are in doubt, why not just use MTW?

 

[Dennis Alwon]

I have never seen 3/8" conduit other than flexible material that was listed for wiring unless it was part of a listed fixture. They do make 1/2" to 3/8" adapter so you could use 1/2" rigid.

 

[Joethemechanic]

I have never seen 3/8" conduit other than flexible material that was listed for wiring unless it was part of a listed fixture. They do make 1/2" to 3/8" adapter so you could use 1/2" rigid.

I haven't either

Just how big of conductors are you thinking of running through this 3/8 pipe?

 

[roger]

Contact the fixture manufacturer, they probably offer the stems and canopy kits in whatever length you need.

Roger

 

[infinity]

They don't make readily available 3/8" EMT and even if they did you cannot use EMT to support a fixture. IMO 3/8" black pipe is probably mechanically identical to a 3/8" stem.

 

[kwired]

Contact the fixture manufacturer, they probably offer the stems and canopy kits in whatever length you need.

Roger

Which should have been ordered with the fixtures, and may have cost less if they were

 

[AZElectrical]

Thanks for the replies. The manufacturer does offer 3/8" pendants with the fixtures, so I'll investigate that option.

They don't make readily available 3/8" EMT and even if they did you cannot use EMT to support a fixture. IMO 3/8" black pipe is probably mechanically identical to a 3/8" stem.

The above quote from infinity is causing me some concern. The existing metal halide fixtures we have installed are connected to a 4x4 junction box mounted to the roof deck via 1/2" EMT. I see under 358.12(5) where EMT is not to be used to support light fixtures. When I read that section, I think of a horizotal section of EMT being used as something to wrap a chain around to hang a fixture from, not something connected to a j-box that is mounted to the roof deck (on a flat ceiling, the conduit is vertical down to the fixture). Is that correct?

 

[masterinbama]

Why not use galvanized? I've used a lot of it for compressed air in water plants.

http://www.doitbest.com/Black+pipe-Southland+Pipe-model-10324-doitbest-sku-424071.dib

 

[kwired]

Thanks for the replies. The manufacturer does offer 3/8" pendants with the fixtures, so I'll investigate that option.



The above quote from infinity is causing me some concern. The existing metal halide fixtures we have installed are connected to a 4x4 junction box mounted to the roof deck via 1/2" EMT. I see under 358.12(5) where EMT is not to be used to support light fixtures. When I read that section, I think of a horizotal section of EMT being used as something to wrap a chain around to hang a fixture from, not something connected to a j-box that is mounted to the roof deck (on a flat ceiling, the conduit is vertical down to the fixture). Is that correct?

If EMT being used as stem for support and as a raceway with supply conductors inside you can not use it.

If EMT is just a piece of metal tubing used as support - it is no longer a raceway, but could be judged insuitable for support depending on conditions. If there are EMT fittings involved in the support especially if installed vertically, that may also reduce the chance of it being judged as suitable for support.

 

[Joethemechanic]

I wouldn't trust any EMT fittings to hang or support anything. The first time I saw EMT I thought it looked cheap. 45 years later my opinion hasn't changed much.

 

[iwire]

I wouldn't trust any EMT fittings to hang or support anything. The first time I saw EMT I thought it looked cheap. 45 years later my opinion hasn't changed much.

So you first so EMT when you were 5 and made a judgement at that point?

Of course you are not an electrician so you don't see a lot.

EMT is very commonly used to support things, just not at the same time it contains conductors.

 

[Joethemechanic]

I flew aircraft before I was 10 too, so what is your point. It looked cheap

 

[buddhakii]

I didn't think you could use a 4 square to support from either unless you use the proper cover designed for a pendant fixture.