Flexible conduit connection to transformers.

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thumper_tx

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I know that flex must be installed on the primary side secondary sides of transformers instead of hard pipe.
I am at a loss to find this requirement in the 2005 codebook.
Serious brain fart going on here.
Having a disagreement with a non electrical engineer about this.
Can anyone help?

Stumped in Texas!
 
I don't think that is a requirement. I think its a good idea, but not a NEC requirement. (But I haven't looked it up, so someone may prove me wrong.)

Steve
 
I know that flex must be installed on the primary side secondary sides of transformers instead of hard pipe.
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Where does it say that you must have a flexible connection? Many transformers have internal vibration damping materials between the core and the case and can be hard piped. There is no specific requirement that all transformers get a flexible connection.
 
I agree with the others, you will not find an NEC requirement for this as it does not exist.

Use whatever method you want to enter and leave a transformer.

Flex, conduit, wireways etc.

It is strictly a design decision, on the job I am currently on the specifications require between 18" and 36" of FMC on both the primary and secondary of any transformers.
 
Thanks guys........ I was very tired of looking. ooks like I may have to eat some crow on this one.
I decided to use 90.4 instead.

Thanks again.
 
If the NEC is being properly enforced, section 90.4 would NEVER need to be cited. For example, take section 230.70(A)(1). If my jurisdiction makes a uniform interpretation that "the nearest point of entrance" is "X" feet, and that is consistenly enforced, 90.4 can be referenced as the enforcement of this ruling.

90.4 can't simply be used becasue you couldn't find another code section to back up your ruling. It should only be used to support the ruling of an actual code section and not on its own.
 
I think it is good practice to have the flex installed. The rigid conduit on the side of the small building may transmit the sound of the xfmr to the walls as this has happened before in this building. The xfmr is very old and noisy as the client does not want to spring for a new one.
Since I am the authority having juristiction it seems I can make the case.
Am I way off base here?
 
thumper_tx said:
I think it is good practice to have the flex installed. The rigid conduit on the side of the small building may transmit the sound of the xfmr to the walls as this has happened before in this building. The xfmr is very old and noisy as the client does not want to spring for a new one.
Since I am the authority having juristiction it seems I can make the case.
Am I way off base here?
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Is your job to design the project the way you think it should be, or is it to make sure it meets the minimum NEC standard?

If it is to meet the minimum standard, then I believe you are "off base". If it is to design the project, then, well, .........
 
Hmmm, I just read 90.4 about 7 times and I find it lets the AHJ be more leinent in cases, allow alternatives and grant special permissions.

In no case do I read in meaning the AHJ can be more strict or make new rules to deny uses that are not called out in code.
 
I find that a lot of Code Enforcement Officials confuse 90.4 with 110.2

110.2 Approval. The conductors and equipment required or permitted by this Code shall be acceptable only if approved.
100 Approved. Acceptable to the authority having jurisdiction.
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There will be no charge for this lesson.
 
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thumper_tx said:
I think it is good practice to have the flex installed. The rigid conduit on the side of the small building may transmit the sound of the xfmr to the walls as this has happened before in this building. The xfmr is very old and noisy as the client does not want to spring for a new one.
Since I am the authority having juristiction it seems I can make the case.
Am I way off base here?
Click to expand...

Noise is beyond the scope of the code, so is "the client doesn't want to spring for a new one". If you require this, you are acting beyond the scope of your authority. If you were in my state, you would be turned in to the inspector licensing board.
 
Ryan

I think that there is some confusion due to this post;

thumper_tx said:
Since I am the authority having juristiction it seems I can make the case.
Am I way off base here?
Click to expand...


Check out his profile.
I don?t think he is the Authority Having Jurisdiction as we think of one, but I do agree that this matter needs to be turned in to the state for investigation as to the permits issued and inspections made.

 
But the profile for Thumper says he is a maintenance supervisor. If its your factory, and your employees, then I think you have every right to have them add flex.

If its a contractor doing the work for a set fee, maybe you should agree to pay for something "above the code".

If you are the inspector for a city or government entity, its not your job to enforce something that's not in the code.

Steve
 
jwelectric said:
[Check out his profile. I don?t think he is the Authority Having Jurisdiction as we think of one, but I do agree that this matter needs to be turned in to the state for investigation as to the permits issued and inspections made.
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Good call Mike, thanks.
 
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