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#71853 - 11/08/06 12:06 AM Supporting of raceways  
Luketrician  Offline
Member
Joined: Jul 2006
Posts: 272
Sale Creek, TN USA
Hello to all,

Noticed something today here at the plant. A run of 3" ridgid coming from a mcc to a 130hp motor goes through a hole in an I beam then ninetys up to the motor itself. There is a nice weld bead that circumfrences the conduit. Looks like a violation of 300.18 (B). In this paragraph though, it goes on to state the following:

"unless otherwise specifically designed to be or otherwise specifically permitted to be in this code"

Would the "specifically designed" statement be refering to an engineering design call that might have been made to allow this type of install to happen?

Luke

[This message has been edited by Luketrician (edited 11-08-2006).]


Luke Clarke
Electrical Planner for TVA.


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#71854 - 11/08/06 06:56 AM Re: Supporting of raceways  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
In my opinion that section requires that the section of raceway be specifically designed by it's manufacturer for weld mounting.

A bulkhead fitting would be an example of a raceway section that might be specifically designed for welding.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#71855 - 11/08/06 07:03 AM Re: Supporting of raceways  
LarryC  Offline
Member
Joined: Jul 2004
Posts: 783
Winchester, NH, US
I thought the NEC doesn't apply to power generation facilities. Plus, I bet the local electrical inspector hasn't been allowed in.

Larry C


#71856 - 11/08/06 11:45 AM Re: Supporting of raceways  
SteveFehr  Offline
Member
Joined: Mar 2005
Posts: 1,213
Chesapeake, VA
RC is a steel pipe, it's inherently weldable. Why would there be any problems welding it to structure?


#71857 - 11/08/06 12:05 PM Re: Supporting of raceways  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Because the code says so? [Linked Image]

Perhaps it's the fact welding tends to remove the required corrosion protection?

Or that improper welding techniques could lead to slag / sharp edges inside the raceway?

I don't have a real answer Steve but to look at another way is why should I weld it when there are so many products designed to support ridge pipe?

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#71858 - 11/08/06 02:00 PM Re: Supporting of raceways  
wa2ise  Offline
Member
Joined: Nov 2002
Posts: 784
Oradell NJ USA
Quote
Why would there be any problems welding it to structure?


I would hope the welding work was done before the wires were put in it... [Linked Image] Can you say "melted insulation"?


#71859 - 11/08/06 07:13 PM Re: Supporting of raceways  
Luketrician  Offline
Member
Joined: Jul 2006
Posts: 272
Sale Creek, TN USA
I think you're right LarryC, It seems to me that the NEC is 'trumped' by the design engineers here at the plant. Is this a good thing?? That question is debateable...

The conduit does have plenty of enamel covering the weld joint though. No rust is visible. I would snap a few pictures for the forum, BUT..I might get into some trouble if I start taking pictures of 'vital' plant equipment.

Wondering about the statement "specificaly designed by it's manufacturer for weld mounting", the hole looks to have been made with a cutting torch, not to pretty. I'll be looking into this further, any more comments would be appreciated, thanks guys & gals. [Linked Image]

Luke


Luke Clarke
Electrical Planner for TVA.



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