My plant is currently using electrical heat tape on existing safety shower piping w/o the GFEP currently required by the NEC. (These systems are quite old.) We are upgrading the safety showers but are reusing the old piping and heat trace. In this case, are we required to retrofit with the now required GFEP? Thank you.
Article 427
- Thread starter straderfh
- Start date
- Status
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: Article 427
Hmmm. But in place of a GFPE you can use a GFCI receptacle or ciruit breaker. If your heat cable is not too long it won't trip the GFCI. I have a lot of heat cable with GFCI's, but it is all pretty short runs under ten feet. Also keep in mind the new type heat cable has a braded metal sheath on the outside. also, I use the self regulating heat cable, wet location rated. I would suggest you look into the self regulating type as it only gets hot when the temp drops, the energy savings over having heat cable on all the time could be substantial.
the above is assuming it is 120V heat cable. If not 120 V and its 277 or 480, then you definitly want GFPE, due to the fire hazard if it faults.
Hmmm. But in place of a GFPE you can use a GFCI receptacle or ciruit breaker. If your heat cable is not too long it won't trip the GFCI. I have a lot of heat cable with GFCI's, but it is all pretty short runs under ten feet. Also keep in mind the new type heat cable has a braded metal sheath on the outside. also, I use the self regulating heat cable, wet location rated. I would suggest you look into the self regulating type as it only gets hot when the temp drops, the energy savings over having heat cable on all the time could be substantial.
the above is assuming it is 120V heat cable. If not 120 V and its 277 or 480, then you definitly want GFPE, due to the fire hazard if it faults.
Re: Article 427
Different but related topic. We use heat trace for a sample line (transporting a chemical through a heated line). We spec GFPE breakers for this use. My question pertains to start up currents. The start up currents for a line can be MUCH higher than the running current. The start up currents typically last 30s - 60s. If a line runs at 36 amps for 30s, then drops down to 22 amps for the rest of the time, can I put this on a 30 amp circuit (and breaker)? Am I allowed "short" start up currents?
Different but related topic. We use heat trace for a sample line (transporting a chemical through a heated line). We spec GFPE breakers for this use. My question pertains to start up currents. The start up currents for a line can be MUCH higher than the running current. The start up currents typically last 30s - 60s. If a line runs at 36 amps for 30s, then drops down to 22 amps for the rest of the time, can I put this on a 30 amp circuit (and breaker)? Am I allowed "short" start up currents?
- Location
- Illinois
- Occupation
- retired electrician
Re: Article 427
srasz,
You need to look at the time trip curve for the breaker that you are using. Looking at a trip curve for one manufacturer's 30 amp breaker shows that the trip time with a 37.5 amp load will be a minimum of 70 seconds and the maximum permitted trip time is never. At 45 amps it should trip between 30 and 300 seconds and between 10 and 50 seconds for a 60 amp load.
Don
srasz,
You need to look at the time trip curve for the breaker that you are using. Looking at a trip curve for one manufacturer's 30 amp breaker shows that the trip time with a 37.5 amp load will be a minimum of 70 seconds and the maximum permitted trip time is never. At 45 amps it should trip between 30 and 300 seconds and between 10 and 50 seconds for a 60 amp load.
Don
Re: Article 427
Don,
I understand what you are saying and it makes sense. What I can't get past is Article 210.23 "In no case shall the load exceed the branch circuit ampere rating". At 36A on a 30A circuit, even for a short time (60s), am I not in violation of this article? There must be an "out" as there are many devices out there that have switching power supplies with very high inrush currents (even though the time is very small). Please help.
Don,
I understand what you are saying and it makes sense. What I can't get past is Article 210.23 "In no case shall the load exceed the branch circuit ampere rating". At 36A on a 30A circuit, even for a short time (60s), am I not in violation of this article? There must be an "out" as there are many devices out there that have switching power supplies with very high inrush currents (even though the time is very small). Please help.
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