Heat Trace - Mixed wattage cables in a single circuit

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csc_wyo

Member
Location
Denver
Occupation
EI&C Engineer - Oil & Gas/Heavy Industry
I have a proposed installation that combines 5w/ft, 8w/ft and 10w/ft self-regulating heat trace cable on single branch circuits. I've argued that this doesn't meet the installation guidelines, but the process engineers tell me they do this all the time. Even if they have, I don't believe this will work based on my understanding of how the cable works.

Cable specified is Nelson LT210-J, LT25-J and LT28-J.

Can someone tell me otherwise? Code/mfgr references?
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
180905-1422 EDT

Your question is incomplete.

If the heat cables are connected in parallel to a 120 V circuit, then not a problem each will operate essentially independent of the others.

If the cables are connected in series, then I don't know. But the same current exists in each cable, probably lower than the current of the lowest wattage cable when it is connected directly to 120 V.

.
 

drktmplr12

Senior Member
Location
South Florida
Occupation
Electrical Engineer
I have a proposed installation that combines 5w/ft, 8w/ft and 10w/ft self-regulating heat trace cable on single branch circuits. I've argued that this doesn't meet the installation guidelines, but the process engineers tell me they do this all the time. Even if they have, I don't believe this will work based on my understanding of how the cable works.

Cable specified is Nelson LT210-J, LT25-J and LT28-J.

Can someone tell me otherwise? Code/mfgr references?

The literature says it is self regulating such that it increases heat dissipation as pipe gets cooler and vice versa. in that regard-why would having different wattage heat trace on one branch circuit be a problem?

Call the manufacturer and ask how they recommend it be connected to achieve what the process folks want. They will tell you if its okay to arrange as suggested.
 
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