I just purchased a home built in 1984-1985. I have some new ceiling lights that are to be used for 90C wire only. I understand that all homes built after 1985 are required to have 90C rated wire but since this one on the fence, what is the easiest way to look at the house wiring and determine if it is 90C or 60C rated?
Wire Temperature Indicators
- Thread starter knottdw
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- Lockport, IL
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- Retired Electrical Engineer
Re: Wire Temperature Indicators
Look for writing along the length of the wire, and specifically for the type of wire. Then look in Table 310.16, to see in which column that wire type appears. You can also look in Table 310.13.
But here?s a hint. The names of wire types start with a 60C rating. For example, type TW has a 60C rating. If they add an ?H? to the name, it means that they added ?one unit of heat,? or 15C, to the rating. Type THW has a 75C rating. A second ?H? adds another unit of heat. Type THHW has a 90C rating.
[ June 30, 2003, 05:43 PM: Message edited by: charlie b ]
Look for writing along the length of the wire, and specifically for the type of wire. Then look in Table 310.16, to see in which column that wire type appears. You can also look in Table 310.13.
But here?s a hint. The names of wire types start with a 60C rating. For example, type TW has a 60C rating. If they add an ?H? to the name, it means that they added ?one unit of heat,? or 15C, to the rating. Type THW has a 75C rating. A second ?H? adds another unit of heat. Type THHW has a 90C rating.
[ June 30, 2003, 05:43 PM: Message edited by: charlie b ]
renosteinke
Senior Member
- Location
- NE Arkansas
Re: Wire Temperature Indicators
I think that the key word here is "house." For general information, Romex marked as "NM-B" has the individual conductors rated at 90 degrees, but the cable assembly is rated at 75 degrees. In other words, a fixture connected to wires that emerge from plastic-sheathed Romex is probably OK.
I think that the key word here is "house." For general information, Romex marked as "NM-B" has the individual conductors rated at 90 degrees, but the cable assembly is rated at 75 degrees. In other words, a fixture connected to wires that emerge from plastic-sheathed Romex is probably OK.
Re: Wire Temperature Indicators
I would suggest that the insulation be known for sure, before connecting the new fixture.
12 TW, is .152 inches in diameter.
12 THHN is .130 inches in diameter.
14 TW is .133 inches in diameter.
14 THHN .111 inches in diameter.
Borrow a micrometer from a machinist or mechanic, and measure the wires. Or clip a small piece and take it to the auto shop at the local high school.
[ July 15, 2003, 10:33 PM: Message edited by: bennie ]
I would suggest that the insulation be known for sure, before connecting the new fixture.
12 TW, is .152 inches in diameter.
12 THHN is .130 inches in diameter.
14 TW is .133 inches in diameter.
14 THHN .111 inches in diameter.
Borrow a micrometer from a machinist or mechanic, and measure the wires. Or clip a small piece and take it to the auto shop at the local high school.
[ July 15, 2003, 10:33 PM: Message edited by: bennie ]
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