Pvc support requirments

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Ricky Manresa

Ricky Manresa

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Just finished a 200A service. I came out the bottom of the main disconnect with 3" pvc and its only about 28" long into an LB where I enter the house.my question is does this short peice of conduit need a strap? I used one but wanted to look and find the code for this and couldnt.thank you stay safe!
 
Welcome to the forum.

Yes, you should strap it, and a Minerallac strap is probably the best fit.

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Ricky Manresa said:
If the conduit is less than 2feet, it counts as a nipple?
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For purposes of taking credit for 60% wire fill and omitting the need to consider wire bundle derating calculations, 2 ft or less counts as a nipple. However, the NEC is not explicit about "unsupported" raceways, no matter how short the length.

In 2008, there was a rule that allowed non-flexible raceways 18" length or less to be "unsupported" (i.e. supported by its terminations), provided that they contained no couplings and didn't terminate where ring knockouts remain. This rule is no longer in the NEC, and no modified rule took its place, despite being a reasonable rule that would settle the issue.
 
Ricky Manresa said:
Just finished a 200A service. I came out the bottom of the main disconnect with 3" pvc and its only about 28" long into an LB where I enter the house.my question is does this short peice of conduit need a strap? I used one but wanted to look and find the code for this and couldnt.thank you stay safe!
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All from recollection here, conduit bodies only need supported within 3 feet on one side, unless they would contain device(es).

If you enter the house pretty much immediately on one side and have 28" on the other side I think that is code compliant. If it were more than 36" to the main disconnect then I think you would need a support on that side.
 
Conduit bodies don't get a free pass from the support requirements. :)

352.30(A) Securely Fastened. PVC conduit shall be securely fastened within 900 mm (3 ft) of each outlet box, junction box, device
box, conduit body, or other conduit termination. Conduit listed for securing at other than 900 mm (3 ft) shall be permitted to be installed in accordance with the listing.
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Ricky Manresa said:
yea thats what i did.it was alittle far from the wall so i used 1"5/8th strut. if the conduit is less than 2feet, it counts as a nipple?
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infinity said:
Conduit bodies don't get a free pass from the support requirements. :)
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Even if the 3” pvc was only 6” long, Infinity posted the section that states you would need a support to be code compliant (but most inspectors use their common sense tho)
 
infinity said:
Conduit bodies don't get a free pass from the support requirements. :)
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Is not supported via being connected to the cabinet that is less than 3 feet away?

What if short enough length that all there is between conduit body and cabinet is just enough to put a TA on and no more? Still needs an additional support?

I know there has been some debates and some changes to short length support rules past few code cycles, some them plain stupid.

I recall first time they messed with this a comment was made at a CEU class I was attending (by the instructor who was also an inspector) that went something like - Is a strap on a 3 foot length of 3 inch RMC between two cabinets supporting the RMC or is the RMC supporting the strap?

I will add my own here and say to increase that 3 inch RMC to 5 or even 10 feet between two cabinets and the conduit is still likely supporting the strap much more so than the strap is supporting the conduit.

PVC - is a little different, but 3 feet really don't matter that much especially 1.25~ or 1.5" and larger- it is about as well supported by the terminations as by any strap on that short of a length, if something is disturbing it one way it is probably disturbing it the other way just about as easily.

Common sense needs to kick in sometimes, it is hard to write rules for "one size fits all" as there is always some situation that never was thought of when making the rule.
 
infinity said:
I agree that the NEC should exercise some common sense with the raceway support unfortunately it does not. :rolleyes:
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Did they change the 18" or less rule needs no additional support? Can't seem to find that in 2017 NEC. Maybe looking in wrong place? Looked in several raceway articles as well as art 300.

IMO 3 feet needs no additional support is plenty sufficient most the time.
 
kwired said:
Did they change the 18" or less rule needs no additional support? Can't seem to find that in 2017 NEC. Maybe looking in wrong place? Looked in several raceway articles as well as art 300.

IMO 3 feet needs no additional support is plenty sufficient most the time.
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Take a look at post #6. I agree that between two solidly mounted objects up to 3' should not require support.
 
infinity said:
Take a look at post #6. I agree that between two solidly mounted objects up to 3' should not require support.
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In my book, conduit body secured pretty much immediately on one side and raceway terminating into solid mounted object within 3 feet on other side is still ok. Larger the raceway the more acceptable it becomes.

Don't ask me how to word code to cover all situations though. I think many inspectors do use a little judgement in this area but others are very strict to wording in NEC, and of course a few that have their own rules regardless.
 
kwired said:
In my book, conduit body secured pretty much immediately on one side and raceway terminating into solid mounted object within 3 feet on other side is still ok. Larger the raceway the more acceptable it becomes.

Don't ask me how to word code to cover all situations though. I think many inspectors do use a little judgement in this area but others are very strict to wording in NEC, and of course a few that have their own rules regardless.
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Take two boxes 18" apart mounted to a poured concrete wall, run a piece of EMT between them, on what planet does that EMT really need additional support? The one cycle code change for the 18" of unsupported raceway was a good one because it actually applied some common sense to the requirement. The removal of that 18" permission was approved by CMP members who have been sitting at a desk for too long. :rolleyes:
 
infinity said:
Take two boxes 18" apart mounted to a poured concrete wall, run a piece of EMT between them, on what planet does that EMT really need additional support? The one cycle code change for the 18" of unsupported raceway was a good one because it actually applied some common sense to the requirement. The removal of that 18" permission was approved by CMP members who have been sitting at a desk for too long. :rolleyes:
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Now they left still in a unknown state as to what is required.

First support must be within 3 feet, but what is the rule when there is less than three feet to begin with?

I say as long as secured at the ends no additional support is needed, some think it must have an additional support, to which you must ask how short before not needed? Nipple long enough to butt two connectors together and no more? how you strap that?
 
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