NEC ART. 725. Allowed min. wire section in a Class 2 circuit

[J-Luc]

Dear all

We are in switzerland and we have a interpretation dilemma with the NFPA 70 (NEC 2011) art. 725.

We produce valve actuators (small servomotor) with a fixed CL2 cable "pigtail" of 3 meters.
Our actuators works with 24Vac in Class 2 circuits. They have a nominal power consumption of 15W.

Its is for us not clear if for our CL2 UL listed cable pigtail,
conductors with a cross section of 20AWG are allowed or not? (need we AWG18)

We are very gradeful for all help that you can give us.

Thank you very much and best regards from switzerland
:?
J-L ucuu

 

[petersonra]

Dear all

We are in switzerland and we have a interpretation dilemma with the NFPA 70 (NEC 2011) art. 725.

We produce valve actuators (small servomotor) with a fixed CL2 cable "pigtail" of 3 meters.
Our actuators works with 24Vac in Class 2 circuits. They have a nominal power consumption of 15W.

Its is for us not clear if for our CL2 UL listed cable pigtail,
conductors with a cross section of 20AWG are allowed or not? (need we AWG18)

We are very gradeful for all help that you can give us.

Thank you very much and best regards from switzerland
:?
J-L ucuu

This is not a NEC issue. it is solely a UL issue. The NEC does not cover the design of components. i think as a practical matter you may well be hated by people trying to use these things if you make them with #20 wire. #18 is a lot easier to work with and less likely to break off.

 

[J-Luc]

Class 2 circuit. AWG20 allowed??? (NEC Art 725)

Class 2 circuit. AWG20 allowed??? (NEC Art 725)

You have absolutely right,
the engineer who test or actuator, says that we need AWG18 as wire section, such as defined in Art 725 of the NEC.
For the time we have AWG20. We have also see that other manufacturer use also AWG20. So we have to understand this new UL request.
Now, I am looking for arguments to convince the test engineer.

Regards

J-Luc

------------

Dear all

We are in switzerland and we have a interpretation dilemma with the NFPA 70 (NEC 2011) art. 725.

We produce valve actuators (small servomotor) with a fixed CL2 cable "pigtail" of 3 meters.
Our actuators works with 24Vac in Class 2 circuits. They have a nominal power consumption of 15W.

Its is for us not clear if for our CL2 UL listed cable pigtail,
conductors with a cross section of 20AWG are allowed or not? (need we AWG18)

We are very gradeful for all help that you can give us.

Thank you very much and best regards from switzerland
:?
J-L ucuu

 

[petersonra]

You have absolutely right,
the engineer who test or actuator, says that we need AWG18 as wire section, such as defined in Art 725 of the NEC.
For the time we have AWG20. We have also see that other manufacturer use also AWG20. So we have to understand this new UL request.
Now, I am looking for arguments to convince the test engineer.

Regards

J-Luc

------------

UL may have changed their rules about this kind of thing, or the agency doing testing for UL may not be applying UL's rules properly. I don't see how art 725 applies to the design of a component like a valve. Article 725 starts out by specifically stating this.

725.1 Scope. This article covers remote-control, signaling,
and power-limited circuits that are not an integral part of a
device or appliance.

 

[J-Luc]

Hi Bob

Not a Valve, a valve actuator. (This is the servomotor)

Thank you very much for your help.

Regards

J-Luc