Wiring channel


  #1  
Old 01-06-01, 05:20 AM
Guest
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Hi, easy question here: I'm running some cable along a plaster and brick wall - only about 1m long between a switch and wall mounted heater. How deep should it be run in the wall and should it be protected with anything?
thanks
Iain
 
  #2  
Old 01-06-01, 06:57 AM
D
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Originally posted by iain
Hi, easy question here: I'm running some cable along a plaster and brick wall - only about 1m long between a switch and wall mounted heater. How deep should it be run in the wall and should it be protected with anything?
thanks
Iain
Any wires inside the wall acording to code has to be at least 1 1/4 or 1 1/2 inches from the edge of the stud (someone may want to correct that measurement but I think I'm close, I think 1 1/2), if it is closer to the edge than that then a metal protector plate must be mounted on the wood where the wire goes thru, the fact that there is brick on the wall I am not sure if that will affect the code or reduce the measurement. The wire must also be have a fastener within 6 inches of the switch box or fixture (or heater), also since it is a heater perhaps someone can advise rather a armered cable is required close to the heater.
 
  #3  
Old 01-06-01, 11:31 AM
Wgoodrich
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1 1/4" is the distance from the surface of a wall to the Romex as a clearance or a metal plate must be installed to protect the wire where the 1 1/4" clearance is not present.

However this is not the main concern in this question post. A channel cut into a brick wall will require PVC conduit. Both flex or Romex is forbidden in direct contact with masonry.

The 1 1/4" is also required for a clearance for PVC to the surface of the wall or a metal plate must be installed as a protector.

Hope this helps

Wg
 
  #4  
Old 01-10-01, 10:34 AM
J
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As an electrical designer I just specify concrete-encased rigid galvanized steel conduit (RGS). It's nearly bomb-proof, and of course totally impractical. But you certainly wouldn't need to worry about those clearances you were questioning.

You'll understand why many contractors think engineers are a total pain in the, well, you know.

Juice
 
  #5  
Old 01-10-01, 04:40 PM
Wgoodrich
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Juicehead you have a very correct idea when it comes to safe and the best way to design this job.

However, if I was the electrician installing your design and you were the engineer with that idea that I had to meet specks for, I WOULD VOTE AS A MINIMUM SLOW TORTURE WITH LOTS OF PAIN FOR THE ENGINEER, while I was intalling that rigid conduit including all the threading.

Do you have any battle scars from electricians?

HA HA !

Wg
 
  #6  
Old 01-10-01, 08:00 PM
RickM
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Cool

WG, good job beating up on that poor engineer!

Section 300-4 is the rule that says you have to be no less than 1 1/4" from the nearest edge of the wood member, or steel plates are required. However, there is an exception that steel plates are not required for "rigid metal conduit, intermediate metal conduit, RIGID NONMETALLIC CONDUIT, or electrical metallic tubing".

That seems pretty scary to me. I can see the metal raceways, but PVC? Just wanted to let you know. (I think this was a change in the 1999 NEC).

Instead of a raceway, what do you all think about uf cable (with the necessary setback)? If the contractor is sheetrocking the walls over this brick/plaster wall, what about just notching the brick/plaster to the desired depth, and then supporting regular NM-B cable with expandable foam, or some such device, at the required locations? This is getting to be a common method of installing romex in the newer foam/concrete forms that some contractors are installing these days. the forms are the ones that you stack up, and concrete gets poured into the void in the middle of the forms. Foam acts like insulation, and is left in place.

Keep up the humor folks, this can get to be a pretty dry forum.

Rick Miell
 
  #7  
Old 01-11-01, 10:20 AM
J
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WG, I was thinking of you when I designed iain's wire run. Kinda thought I'd hear about it. I enjoy poking fun at engineers/designers. We're definitely a strange bunch. There's a joke about "What's the difference between a civil engineer and a mechanical engineer?", and the answer is "Mechanical engineers build weapons, while civil engineers build targets!". I've often wondered, with all the engineers in the world, why people chose to pick on lawyers! Ha Ha Ha!

RickM, as far as the NEC allowing PVC less that 1-1/4" I think the average homeowner will be driving picture hanging nails and an occasional drywall screw for a shelf bracket or something, and if you ever hit a PVC pipe in a wall with a drywall screw, or even a drill bit, you know the you definitely have hit something that ain't wood, and most likely have not penetrated it. Only on a few occasions have I seen someone so persistant that they put a screw through a pipe of any kind. It was always plumbing and eeeewww, what a mess. So although certainly possible to do to PVC and even EMT, and although I also personally don't like to, it's generally unlikely to penetrate a conduit. That's what I figure the NEC figures.

Iain, I hope our little discussion on your topic has helped.

Juice
 
 

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