Motor's

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ken44

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Austin, TX
Are there any NEC requirements or other standards that anyone may know about that state that EMT (or similar raceways) cannot be ran directly from a panel board or junction box to a motor's connection box without the use of flexible conduit at the motor? I would think that with all the vibration from a motor, that it would not take long to lose the bond between the conduit and the motor's connection box (or as we called it in the Navy, a peckerhead).
 
Why would anyone hardpipe to a motor in the first place? Are you just curious if it's legal or do you have an electrician wanting to do it that way?

Everytime you changed a motor you'd have to rebend the pipe to match the new motors j-box connection.
 
This is not a NEC issue. Vibration is addressed ten times in the 08 and motors and transformers are not mentioned.
 
Motor's

Yes, there is a contractor who wants to hard pipe directly to the motor and I could not find anything in the NEC that says it is illegal.
 
ken44 said:
Are there any NEC requirements or other standards that anyone may know about that state that EMT (or similar raceways) cannot be ran directly from a panel board or junction box to a motor's connection box without the use of flexible conduit at the motor? I would think that with all the vibration from a motor, that it would not take long to lose the bond between the conduit and the motor's connection box (or as we called it in the Navy, a peckerhead).
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I don't think the NEC prohibits it, but putting in a short piece of flex makes working on it later a whole lot easier.

I have seen it now and then, I suspect because it is cheaper than adding in a section of flex.
 
tom baker said:
Often a flexible wiring method is used as its easier, and many times the motor has to be moved for alignment.
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We have a customer that puts most of their motors on cord and plugs because their product is very time critical and even a few minutes difference in changing out a motor or having to pull one so repairs can be done on a piece of equipment could cost a lot of money.

It adds to the cost of install but keeps the plant up and running.

The spare motors already have a cord and plug attached.
 
ken44 said:
Yes, there is a contractor who wants to hard pipe directly to the motor and I could not find anything in the NEC that says it is illegal.
Click to expand...

I was hoping you were just curious. I never thought any electrician would want to hardpipe a motor, it doesn't make sense to do it that way....
 
Hard pipe ,in addition to to the vibration factor, I think would get in the way if the motor ever needed to be replaced. The flex method provides a source of vibration isolation and offers flexability if the opening on the a replacements motor housing is in a different location. Purely just opinion though.

BTW I have seen transformers hard piped in the past
 
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ken44 said:
Yes, there is a contractor who wants to hard pipe directly to the motor and I could not find anything in the NEC that says it is illegal.
Click to expand...

Ken,
I am curious.
If ""Vibration is addressed ten times in the 08 and motors and transformers are not mentioned.""
and you have ""Vibration"",
Then I don't think you need to be concerned
whether its a motor or not.

That said, what was the final outcome?

Good Luck.
:)
 
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