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#181522 10/14/08 11:46 AM
Joined: May 2003
Posts: 1,158
What is the temp rating of nm-3 I assume its 60C

dougwells #181524 10/14/08 12:22 PM
Joined: Aug 2002
Posts: 402
NMD3 has a temp rating of 60ºC

jdevlin #181548 10/15/08 11:57 AM
Joined: Jun 2006
Posts: 613
Yup 60 and be careful replacing light fixtures fed with NMD-3 the new fixtures might destroy the insulation at 90 degrees.

mikesh #181552 10/15/08 06:34 PM
Joined: May 2003
Posts: 1,158
Yup thats why i was asking Customer thinks i should throw my code book out the window to I think laugh

dougwells #181565 10/16/08 10:44 AM
Joined: Jun 2006
Posts: 613
Since customers are always right it does make it interesting to tell them the only fixtures you will install do not have a temperature requirement. That usually means fixtures with a drop. Still lots of choices but almost no fixture that mounts directly on the box is required to be supplied with 90 degree wire. My company had such a customer and I refused to install 2 fixtures which I thought should be rewired with NMD90. The boss backed me and asked the customer to sign a letter verifying we did not install his fixtures so we would not be held liable. I installed blank covers and left. I don't know if the customer installed the fixtures or rewired the outlet but we stopped working for them at the same time.

I must say I loved working there because they had a quality and accuracy policy. Our motto was get good first and get fast later. My Superintendant always asked a prospective employee some question about mistakes and what would you do. No one who claimed to not make mistakes was ever hired nor was anyone that did not immediately answer they would bring it to the company's attention ASAP.

mikesh #181599 10/18/08 12:43 AM
Joined: Nov 2005
Posts: 141
Hi Doug,

Please do NOT throw the CEC out if you get asked to do so. I never did that at all.

Sometimes we lost a bit of business because we wouldn't do so but it was business I didn't want to do anyways. I was always proud of the fact that we did the stuff that was safe, particularly above and beyond the Canadian Electrical Code requirements anyways.

If something goes wrong the lawyers will try to blame you when the place either burns up or someone gets electrocuted.

We had one guy here in Edmonton that got his ass sued off and he lost his whole business with having to pay out about $1,000,000 because he took a shortcut that was outside the CEC. The lawyers got him in civil court. To make it worse, his insurance company abandoned him as well, since he deliberately went against the normal CEC rules. I don't know how long it's going to take him to make up and pay for that "shortcut".

After I talked to the guy when it was all over, he told me that he really regretted making what he said was a "stupid and dumb" decision.

All I can say is - stay with the Code and you are probably off the liable hook.

dougwells #206128 05/27/12 06:17 PM
Joined: May 2003
Posts: 1,158
I am looking at a basement suite renovation this is an existing suite.The baseboard heater circuits are wired in NM-3 Can I install a junction box behind the heater to bring the conductors up to a 90C rating and and use the baseboard heater to conceal the JB ? . another question i have does this affect the wall thermostat terminal temperature rating Thanks

dougwells #206137 05/28/12 02:18 AM
Joined: Jun 2004
Posts: 1,273
From an engineering point of view I would not regard a buried/ adjacent j-box with a THWN-2/THHN tap as being any kind of cure.

The distance is too short for such a conductor to bleed off enough heat -- so as to bring the effective imposed load upon the NM-3 below its 60 C rating.

If buried, that goes double.


For peace of mind: the transition needs to be significant, perhaps a run of EMT with THWN-2 in it. Keep the baseboard heater away from the NM-3.

A fire in a basement = total disaster.


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