aod
Member
- Location
- Owings Mills, MD, USA
I understand it is not a safe practice to do so but is it a code violation to connect a 60deg Rated cable to a 75deg rated equipment lug? What could be the possible issues/outcomes in doing so?
Temperature Rating - Cable vs Equipment Lug
- Thread starter aod
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- Massachusetts
That is a common situation and nothing will happen as long as the circuit ampacity is based on 60C.
aod
Member
- Location
- Owings Mills, MD, USA
The reason i ask is that some manufacturer documentations state clearly that - on a 75degree rated equipment lug, a 60degree rated cable cannot be used. I was wondering if I missed something code related or a scenario that would cause the insulation of the cable to fail.
Thanks
Thanks
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- Placerville, CA, USA
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- Retired PV System Designer
Some lighting or heating appliances get very hot and require a specific wire temperature rating.
This is NOT the same as the terminal temperature rating used for ampacity calculation.
mobile
This is NOT the same as the terminal temperature rating used for ampacity calculation.
mobile
- Location
- Massachusetts
aod
Member
- Location
- Owings Mills, MD, USA
There isn't a specific equipment that i have in mind. I was reviewing a Cable/Wire specification on a drawing which called out for the "equipment lugs to be equal to or exceed the cable temperature rating" which seemed to not match manufacturer recommendations. Hence the question.
Electric-Light
Senior Member
Plastics (including PVC) softens and ages faster at higher temperature.
The heat produced by equipment adds temperature to whatever conditions existing with the power off. The conductor can sink through insulation at elevated temperature and thin out the insulation even if not overnight. For example, 80C ballast case edge slowly hot knifing into conductor through 65C insulation. Average ballasts are rated for 70C case temp and external ballast for CFL and high ambient models are generally rated 90C case. Other thing is increased aging causing them to become brittle and cracked sooner than expected. 2x26W CFL cans use roughly the same power as two lamp T8 but have more ballast failures. It's easy to see why when you see how the heat from lamps are congregated into much smaller space and the placement of ballast puts it into a much hotter spot.
The cable insulation should match or exceed instructions or the temperature rating of materials at the connection point. You'll see space heater with silicone or glass fiber insulation and go sufficient distance to a termination point where it is far enough away to stay cool enough to connect with standard cable.
The heat produced by equipment adds temperature to whatever conditions existing with the power off. The conductor can sink through insulation at elevated temperature and thin out the insulation even if not overnight. For example, 80C ballast case edge slowly hot knifing into conductor through 65C insulation. Average ballasts are rated for 70C case temp and external ballast for CFL and high ambient models are generally rated 90C case. Other thing is increased aging causing them to become brittle and cracked sooner than expected. 2x26W CFL cans use roughly the same power as two lamp T8 but have more ballast failures. It's easy to see why when you see how the heat from lamps are congregated into much smaller space and the placement of ballast puts it into a much hotter spot.
The cable insulation should match or exceed instructions or the temperature rating of materials at the connection point. You'll see space heater with silicone or glass fiber insulation and go sufficient distance to a termination point where it is far enough away to stay cool enough to connect with standard cable.
It's a conservative approach to match terminal lug to element side lead insulation for terminal lug interfacing elements and equipment service entry. You would match or exceed line side insulation to instructions but it doesn't mean you have to run fiberglass insulated cable.
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