3 phase vs 1 phase, and 208V vs 120V. Question about circuit breakers.

I'm creating an installation plan for heat tracing, and am having trouble understanding how to power it.

The manufacturer recommends a 2-pole GFCI circuit breaker. The heat tracing cable is rated for 100-130 Vac. The cable is 3W/ft and will be about 250 ft long.

Is it possible to provide 120V with a 2-pole breaker and how would I wire that up?

We have spares on a 208/120V 3phase, 4 wire panel.
 

GoldDigger

Moderator
Staff member
I'm creating an installation plan for heat tracing, and am having trouble understanding how to power it.

The manufacturer recommends a 2-pole GFCI circuit breaker. The heat tracing cable is rated for 100-130 Vac. The cable is 3W/ft and will be about 250 ft long.

Is it possible to provide 120V with a 2-pole breaker and how would I wire that up?

We have spares on a 208/120V 3phase, 4 wire panel.
It is not possible to get 100-130V from 208Y/120 and still break both sides, unless you manage to arrange to have one CB pole on the neutral. For the latter, you would need to use a free standing or DIN rail breaker. Or use only two phases on a three phase panel and use the third phase for neutral.
 

Jraef

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Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
I agree. I believe the 2-pole spec is a mistake.
Or the system came from overseas where they use 2 pole breakers where one pole is just a switch for the neutral. Lot's of foreigners get really confused about how we do things here. They adapt their products to work on 120V so they can sell them here, but have no clue how our distribution system is configured (or don't care).

That would make me want to double check whether this was UL listed or not...
 

infinity

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Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I'm creating an installation plan for heat tracing, and am having trouble understanding how to power it.

The manufacturer recommends a 2-pole GFCI circuit breaker. The heat tracing cable is rated for 100-130 Vac. The cable is 3W/ft and will be about 250 ft long.
Do you have a link to the product?
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
It is not possible to get 100-130V from 208Y/120 and still break both sides, unless you manage to arrange to have one CB pole on the neutral. For the latter, you would need to use a free standing or DIN rail breaker. Or use only two phases on a three phase panel and use the third phase for neutral.
They make "switched neutral" breakers. They were required for gas pumps at one time. Not sure it they opened the hot and a neutral on a trip, of if they just opened the neutral on a manual shut off.
 
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