I want to make sure I am applying this exception correctly. If I have a 60 amp continuous load, with 75 degree terminations at the breaker, the load and using 75 degree conductor(110.14 C), 125% of 60 is 75 amps requiring #4 conductor (85 amps) and an 80 amp breaker (240.4(b)). The grounded conductor of this 120 volt single phase to neutral would only need to be a number 6? Where in branch circuits does it state that the grounded conductor is not protected by the OCPD? If it is protected, what kind of protection is it? Is a branch circuit only the ungrounded conductors? The definition of branch circuit seems to leave this as a possibility. Thank you.
210.19(A )exception 2
- Thread starter jmccamish
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jmccamish said:
I think your terminology is off a bit.
Firstly. except. 2 from art. 210.19(A)(1) is when there is no overcurrent protection. For an example-- from the meter base to the first disconnect where there is no main breaker.
Your calculations are good. Depending on the load the breaker may be allowed to be a 90amp using 240.4(b) or even more in some circumstances.
The last part I don't understand. If the load is continuous and the neutral is carrying the same load as the grounded conductors then it needs to be the same size. Perhaps explaining where the #6 comes into play will help us understand what you are asking.
jmccamish said:
Yes
jmccamish said:
It doesn't. . It based upon your usage of the grounded conductor.
jmccamish said:
I believe the main reason for your confusion is the shorthand that we all commonly use. . We usually refer to the grounded conductor as the neutral because the grounded conductor usually is a neutral. . But a 3phase corner grounded delta system has 2 ungrounded phases and one grounded phase. . You run 3phase circuits for 3phase loads out of a 3pole breaker, and when you have a corner grounded delta it's still commonly done with 3pole breakers. . The grounded phase conductor is connected to one pole of the 3phase breaker and then is a grounded conductor connected to an overcurrent device. . The neutral [if used] is "Grounded conductors that are not connected to an overcurrent device".
jmccamish said:
The branch circuit is all conductors, grounded, ungrounded, and grounding.
Dennis Alwon said:
210.19 doesn't apply to the service
Dennis Alwon said:
A #4 [85a] could go on a 90a breaker based on 240.4(B) + 6(A). . But the #6 [65a] would need a 70a breaker.
Dennis Alwon said:
Dennis,
210.19(A)(1) Ex2 is new for '08. . It allows a neutral conductor for a continuous load to be sized at 100%. . 125% is no longer required.
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- Chapel Hill, NC
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Thanks David
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- Chapel Hill, NC
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- Retired Electrical Contractor
dnem said:
I don't get this. Why would the neutral (#6) come into play with the OCD in this situation.
branch circuit conductors
branch circuit conductors
If the branch circuit conductors are all the conductors, then the why wouldn't the grounded conductor need to be protected per 210.20 which points to 240.4 which bases the OCPD off the size of the conductor in 240.4(B). If this is the case a #6 75 degree copper cannot be protected by a breaker higher than 70 amps. Seems like a conflict to me.
branch circuit conductors
If the branch circuit conductors are all the conductors, then the why wouldn't the grounded conductor need to be protected per 210.20 which points to 240.4 which bases the OCPD off the size of the conductor in 240.4(B). If this is the case a #6 75 degree copper cannot be protected by a breaker higher than 70 amps. Seems like a conflict to me.
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- Chapel Hill, NC
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- Retired Electrical Contractor
Check out 240.15 Ungrounded conductors. Then read art. 240.22. Art 240.22 does not require OCP on the grounded conductor.jmccamish said:
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