Cable Entry/Exit Points and Electric Codes

brianafischer · October 24, 2006

Just a quick question. Are there any rules/codes that specify where cable entry/exit points must be on a control panel. I know that it is good practice to have cable connections ONLY on the sides of the enclosure, but is it legal to put connections through the back/top/bottom of the panel? Thanks!

jstolaruk · October 24, 2006

Well, if it is, I've been illegal for a long time.

David Nelson · October 24, 2006

it is legal to put them where ever you wish. so as long as the connections are made with an approved device. the panel is approved for that type connection in a given environment and they are not hazardous to people. let me check my nec book. note approved means something that is listed by a testing agency such as "UL" for the purpose it is be used for.

TERdON · October 24, 2006

On the sides? We always try put cables in through the bottom. Least risk of fumes etc entering the cabinet that way. Functionally, the back and the sides are almost equivalent to that. We try to avoid entering cables through the top, however (lots of risk of leakages!), and normally only do it with really thick power cables. Still, I suppose I'm not of any help at all. Electrical codes in the US probably aren't the same as here... Edit: For you wondering why we don't like entering cables from the top, I'm in the surface treatment plant building business. In some of the plants, hydrochloric acid has been dripping from the roof around me sitting programming... :/ Edited October 25, 2006 by TERdON

forqnc · October 25, 2006

All my panels have had entry/exit points placed where they are safe/practical. An order I try to follow is bottom-sides-top. Top is always a last resort for the same above mentioned leakage. I do not work in a leaky environment, but our sprinkler system could go off someday. As far as NEC code, I believe the NEC does not extend to Industrial control panels, but OSHA does. I just try to build panels with common sense and safety in mind.

robh · October 25, 2006

You may find some more information in the UL 508A standard for industrial control panels. I looked a little bit, but UL standards are so fun to read. I try to always come out of the bottom of the box, but its not a perfect world so if I have to come out on top or the sides and it is in a place where water or any other nasty could get in I try to use a gasketed hub.

David Nelson · October 25, 2006

actually the NEC started enforcing code in 2005 for industrial control panels. the section is 409

forqnc · October 26, 2006

Thanks for the infomation, I got some reading to do.

BobLfoot · October 30, 2006

Don't know what world most of the posters to this topic live in, but in the locations I've been to MCC's always have cable trough or ladder above the racks and most of the conduits drop into this trough. Most of the Plant Floor Control Panels, some of which have motor starters in them also bring signal and power cables in from above. Guess most of the installer/designers figured that point to point just below the cieling was easier to route conduit than under the floor. Also the extra conduit to reach the bottom and or sides was more cost on the project.

TimWilborne · October 30, 2006

Most of mine in very harsh environments. Through the bottom of the enclosure or the sides near the bottom. Yes connectors should be sealed but foreign debris still manages to get in.

BobLfoot · October 30, 2006

Found this NEC Digest Article about Section 409 which was brief and to the point if any one is interested.

TimWilborne · October 30, 2006

I must have missed what you are talking about Bob, or by brief did you mean not specific?

BobLfoot · October 30, 2006

The article is an overview with very few specifics, but gives enough for you to get the gist of 409 I thought.

TimWilborne · October 30, 2006

Oh I see, and now I must purchase UL 409 for details. Slick one Bob, you should be in advertising Kidding of course. I've never worked in a UL shop or even seen the guidelines

BobLfoot · October 30, 2006

Guess I'm spoiled - our engineering dept has an engineer who handles NEC compliance. Any question he has the code and I can ask him or read it for myself. Just thought this post would give folks an idea of what they wer in for.

JRaef · October 30, 2006

Note that this is in the 2005 NEC, which has only been adopted in a handful of states at this point.

brianafischer · November 8, 2006

Thanks for the advice guys. I have connections going through the rear of the panel, and everything is ok. Although it always makes me question standards when I am doing something I have not seen before...

TimWilborne · November 9, 2006

If you mean through the rear of the enclosure but below the panel then that is fine. I have ran into one panel that the wire entered through the rear of the enclosure behind the panel. First I have no idea how they made any time doing this but it made it a real pain to trace where the wire was exiting the panel

brianafischer · November 9, 2006

We cut a rectangle in the bottom-right portion of the panel and connected the wires through strain gauge/fittings/connectors on the rear of the enclosure.... Sometimes I don't realize how confusing my wording can be!!!!