Top vs. bottom connection

[smccluer]

Does the code require top vs bottom connection to a device such as a switch,CB, or contactor when it is mounted vertically? The following were as close as I could find:
240.81 - On CB handles, UP equals ON
404.6(A) - Gravity must default to OPEN on single throw knife switches
Electrical diagrams seem to always show the line side on top and load on the bottom. Does the NEC actually require this?

 

[gene]

Re: Top vs. bottom connection

Check 404.6 (C)

 

[infinity]

Re: Top vs. bottom connection

I would say unless you're refering to knife switches the answer is no.

 

[gene]

Re: Top vs. bottom connection

Aren't disconnect switches, fused or otherwise, actually knife switches. To ensure that the blades are not energized in the open position and gravity would not close and energize the switch you would have to feed the top set of contacts. The code book may not state the line side must be the top, but with the other restrictions, you would be hard pressed to find another option IMO.

 

[jim dungar]

Re: Top vs. bottom connection

Unless the terminals are specifically marked LINE and LOAD, circuit breakers are not restricted as to top or bottom feed per 110.3(B).

 

[mdshunk]

Re: Top vs. bottom connection

I agree that since feeding the LINE in the top and the LOAD out the bottom is such a common practice, deviating from this may cause an unnecessary hazard to (semi-skilled) personnel during troubleshooting and maintenance. Though not required by code (unless the terminals are marked), I consider this good workmanship. I seem to remember something in the NESC about this, but the NEC is mute on the topic.

[ May 18, 2005, 06:55 PM: Message edited by: mdshunk ]

 

[infinity]

Re: Top vs. bottom connection

In response to Gene's question, disconnect switches are not knife switches as referenced in 404.6.

 

[buck33k]

Re: Top vs. bottom connection

I hope this isn't too far off the subject, but what about ct cans where the cts are mounted vertically and fed from underground. Do you go to the bottom first or does it depend on how you want to exit? Is there a common practice?

 

[john m. caloggero]

Re: Top vs. bottom connection

Some UL listed equipment is identified with "Line" and "Load" markings so that you can bottom feed for underground supplies.

 

[mc5w]

Re: Top vs. bottom connection

In the case of underground feed for a CT cabinet you would want a slack loop before reaching the CTs so that ground movement will not mess up the metering. Taking the conductors to the top of the CT cabinet and doing a P bend would do this. If the conductors are sufficiently flexible then a U bend would also work.