Mike Furlan
Member
- Location
- Lemont Il
Does the ampacity of Flexible Cord and Cable have to be adjusted when used to supply a continuous load?
Continuous Load, Flexible Cord and Cable
- Thread starter Mike Furlan
- Start date
- Status
- Location
- Logan, Utah
The load ampacity would need to be adjusted if it is continious, see 210.19. This could cause you to have to use a larger cord for the adjusted ampacity of the load.
Chris
Chris
Mike Furlan
Member
- Location
- Lemont Il
That make perfect sense.
But, Article 210 covers branch circuits. My flexible cord is plugged into a branch circuit.
Article 400, that covers Flexible Cord and Cable doesn't mention any continuous load adjustments, just temperature adjustments.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
The ampacity of any conductor is not impacted by the type of load it serves. Ampacity is a limit on the amount of current we are allowed to pass through the conductor. The question of how much current you need to be able to pass is a matter of calculating the load. That is where such considerations as continuous versus non-continuous loads come into play.
Mike Furlan
Member
- Location
- Lemont Il
All of this makes sense.
However the only references in the code to continuous loads are in the Articles on Branch Circuits and Feeders.
The flexible cord I am concerned about powers utilization equipment, and is plugged into a branch circuit, but is not itself a branch circuit.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
I am not sure what point you are trying to make. The answer to your original question is a simple ?no.?
The design process for feeders and branch circuits always starts with figuring out what the load is. The next step is to select a conductor that has sufficient ampacity for that load. The final step is select an overcurrent device that can protect the conductor.
What you are describing appears to be outside the scope of the NEC. If a piece of utilization equipment gets its power via a plug & cord connection, then that cord is most likely supplied with the equipment. In that case, it is up to the manufacturer to ensure that the cord is adequate for its purpose. The user need not question its ampacity, since the NEC does not apply to manufactured equipment.
The design process for feeders and branch circuits always starts with figuring out what the load is. The next step is to select a conductor that has sufficient ampacity for that load. The final step is select an overcurrent device that can protect the conductor.
What you are describing appears to be outside the scope of the NEC. If a piece of utilization equipment gets its power via a plug & cord connection, then that cord is most likely supplied with the equipment. In that case, it is up to the manufacturer to ensure that the cord is adequate for its purpose. The user need not question its ampacity, since the NEC does not apply to manufactured equipment.
Mike Furlan
Member
- Location
- Lemont Il
Well, Article 400 covers flexible cords and cables. And I would think that in most cases it would be used to power utilization equipment.
The item in question was not manufactured, but was specially built.
Aren't the ampacities in 310.16 continuous load ampacities? In 210.19 (A) Exception 2, you can take 100% of the total load, continuous or not, as the limit on grounded conductors that don't land on an overcurrent device. I think this whole 125% thing is because of circuit breakers.
This would seem to imply that continuous or not doesn't matter for a cord that isn't landing on a circuit breaker.
This would seem to imply that continuous or not doesn't matter for a cord that isn't landing on a circuit breaker.
Mike Furlan
Member
- Location
- Lemont Il
I think I found my answer elsewhere, in Article 670, Industrial Machinery.
Requires conductors to be sized at 125%, with few exceptions.
- Status