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#101620 - 03/27/02 04:14 AM cable tray  
SamC  Offline
Joined: Mar 2002
Posts: 15
Teck cable,in verticle runs of cable tray, do cables need to be P-Clamped? We hired a fresh j/m out of school last summer and he mentioned this was now code. I never thought anything of this (because I was not on that job), til last month. When I ty-wrapped teck down a verticle run and was remined of this so called rule by the shop leadhand. He said the new guy must know the rules, He just came from school. I found nothing in the CEC. Am I missing something?

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#101621 - 03/27/02 06:37 PM Re: cable tray  
golf junkie  Offline
Joined: Apr 2001
Posts: 507
York, NE
No answers here....just more questions.

What is a P-clamp?

I have always ty-wraped cables in cable tray and have not seen it done any other way.


#101622 - 03/28/02 12:42 AM Re: cable tray  
SamC  Offline
Joined: Mar 2002
Posts: 15
P-clamps are steel clamps used to secure cables and pipe to strut or tray. There are 2 types we use at our plant, one is U shaped with a saddle on the inside of the U, you would slip the clamp over the cable hook the open end on the tray rung or strut and tighten the saddle down with the screw that is attached to the clamp. The other style is a 3 piece unit. If you have access to the Unistrut Catalogue you should find them there.

#101623 - 03/28/02 05:44 PM Re: cable tray  
Tony Moscioni  Offline
Joined: May 2001
Posts: 144
Rule 12-120(2)

Conductors in vertical raceways shall be supported independently of the terminal connections and at intervals not exceeding those specified in Table 21 and such supports shall maintain the continuity of the raceway system without injury to the conductors or their covering.

Intent for Rule 12-120(2).

We intend that the weight of conductors, when mounted in the vertical position, not be supported at electrical equipment terminations. When the weight is considerable, the top support alone should not be relied on; intermediate supports should also be used. Conductors installed in vertical raceways are to be supported in accordance with Table 21.

Field Considerations for Rule 12-120(2).

There are types of single- or multi-conductor cables that because of their construction have, when run vertically, similar problems as conductors installed in vertical raceways. The cable manufacturer should be consulted to determine the maximum vertical run between conductor supports, or cables specifically designed to be run vertically should be used.

Tie wraps are intended and approved for securing cables and conductors in place for spacing, but not for supporting them.

This means tie wraps may not bear any weight.

Tie wraps are not permitted to support cables in vertical sections of cable tray.
Tie wraps may be used in horizontal sections of cable tray to maintain cable spacing.

Tie wraps shall be suitable for the environment (indoor, outdoor, sunlight, etc)

Tony Moscioni
Electrical Inspector
Electrical Safety Authority

#101624 - 03/28/02 08:32 PM Re: cable tray  
golf junkie  Offline
Joined: Apr 2001
Posts: 507
York, NE
Sam, thanks for the info....I'll check it out.


[This message has been edited by golf junkie (edited 03-28-2002).]

#101625 - 03/31/02 12:50 PM Re: cable tray  
SamC  Offline
Joined: Mar 2002
Posts: 15
Thanks Tony I'll pass this on to the guys in the shop. I do have couple of questions though, 1>what about a verticle run that is used only to change the tray elevation say 15', or 2>a 10' drop into top of cabinate? In these 2 examples the termination at equipment will not be supporting any wieght.


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