feeder length

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MasterDic

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anyone ever been called for different feeder lengths due to conduit entry and lug location? My gripe is our inspector had a problem with but didnt shoot down our gear because i have 4 4" conduits with 1 1/8" spacing between each landing onto lugs about 18" below. Without getting into all the bends in the conduit run leading upto our gear exactly how exact do parrallel runs have to be? never been called for a couple extra inches, is it just me or is this a bit excessive on interpretation?
 
I looked at an installation just like that today. Didn't even occur to me to check the conductor length.

In the past I have seen installations where I have felt this was an issue, but the difference was feet not inches.
 
mistermudd said:
I looked at an installation just like that today. Didn't even occur to me to check the conductor length.

In the past I have seen installations where I have felt this was an issue, but the difference was feet not inches.
Click to expand...

I am probably completely ignorant of some important
factor here, or completely misunderstand the issue,
but I'll ask anyway, since I don't understand
why this would be a big issue.

I thought that the electric wave propagated about
2/3 the speed of light. Speed of light is 186,000 miles/sec,
so this is about 120,000 miles/sec. At 60 Hz, there
would be about 2,000 miles between "peaks", at
about 5,000 feet per mile, this is about 10 million
feet between "peaks". If the runs were 10 feet
different in length, the "peaks" would only
be 1 millionth out of phase or about 0.0004 degrees.
Is this a big deal?

I apologize in advance if this is a dumb question.
 
rexowner said:
I am probably completely ignorant of some important
factor here, or completely misunderstand the issue,
but I'll ask anyway, since I don't understand
why this would be a big issue.
Click to expand...
Look at it from a difference in resistance perspective and the amperage per conductor as a result of that difference.

It would be nice if the requirement stipulated a tolerance... but in lieu of that, one can approximate the differing amperages, and everything is OK as long as the amperage is less than the ampacity.
 
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Smart $ said:
Look at it from a difference in resistance perspective and the amperage per conductor as a result of that difference.
Click to expand...

Thanks, that clears it up. The current on the shorter
wires might exceed the rating if they were too far out
of balance.

I knew I was missing something that should have been
obvious. Thanks.
 
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