grounded conductor overcurrent protection

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don_resqcapt19

don_resqcapt19

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I know that we do not protect the grounded conductor directly with an OCPD. I also know that the code rules often permit the grounded conductors to be smaller than the ungrounded conductors for services, feeders, and in some cases branch circuits. What code section permits a grounded conductor to be installed without overcurrent protection. The wording in 240.4 says "conductors", not "ungrounded conductors" and therefore applies to the grounded conductor.
Don
 
don_resqcapt19 said:
I know that we do not protect the grounded conductor directly with an OCPD. I also know that the code rules often permit the grounded conductors to be smaller than the ungrounded conductors for services, feeders, and in some cases branch circuits. What code section permits a grounded conductor to be installed without overcurrent protection. The wording in 240.4 says "conductors", not "ungrounded conductors" and therefore applies to the grounded conductor.
Don
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240.22 Grounded Conductor.

No overcurrent device shall be connected in series with any conductor that is intentionally grounded, unless one of the following two conditions is met;
(1) The overcurrent device opens all conductors of the circuit, including the grounded conductor, and is designed so that no pole can operate independently.
(2) Ehrt trwuitrf ny 430.36 or 430.37 for motor overload protection.
 
don_resqcapt19 said:
I know that we do not protect the grounded conductor directly with an OCPD. I also know that the code rules often permit the grounded conductors to be smaller than the ungrounded conductors for services, feeders, and in some cases branch circuits. What code section permits a grounded conductor to be installed without overcurrent protection. The wording in 240.4 says "conductors", not "ungrounded conductors" and therefore applies to the grounded conductor.
Don
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I understand what you are saying, but does that mean, by that logic, that it applies to the EGC as well? I think 240.4 is intended to apply to ungrounded conductors. I, like yourself, like the code to say what it means, but I think in this case it doesn't. I believe 240.4 applies only to the ungrounded condcutor, and that 310.10, 210.19, 215.2 and 230.42 take care of the grounded conductor.
 
don_resqcapt19 said:
I know that we do not protect the grounded conductor directly with an OCPD.
Click to expand...
We don?t. But just for the sake of its entertainment value, let me say that the electrical rules for ships sometimes do require the use of two-pole breakers that switch the ungrounded and the grounded conductors that serve single phase 120 volt loads.
don_resqcapt19 said:
What code section permits a grounded conductor to be installed without overcurrent protection.
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My guess is that protecting the grounded conductor ?directly with an OCPD? is not necessary, and therefore is not required by the code. Can you conceive of a circumstance in which, despite the entire circuit having been installed in accordance with code, an overcurrent condition can exist in the grounded conductor, without there being the same overcurrent condition also existing in the ungrounded conductor? I cannot.
 
Pierre,
I am not saying that the grounded conductor should have an OCPD installed in series with it. I am just saying the the current code rule requires the grounded conductor to be protected at its ampacity. This protection is provided anytime the grounded conductor is the same size as the ungrounded conductors of the same circuit. The only current that can flow (forgetting harmonics) on the grounded conductor must also flow on one or more of the ungrounded conductors of the same circuit, thus the grounded conductor is protected at its ampacity when it is the same size as the ungrounded conductors. There are a number of rules in the NEC that permit the grounded conductor to be smaller than the ungrounded conductor and in these cases the grounded conductor is not protected at its ampacity as required by 240.4.
Don
 
Charlie,
My guess is that protecting the grounded conductor “directly with an OCPD” is not necessary, and therefore is not required by the code.
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I agree that such protection is not necessay, but I don't agree that it is not required by the code. The current code wording requires overcurrent protection of "conductors". A grounded conductor is a "conductor".
Don
 
Ryan,
Don, are you going to make a proposal to clarify this? I can put it on my "to do list" if you aren't.
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I'll add it to my list, but multiple proposals sometimes get more attention by the CMP, espeically where they are the same concept by not identical word for word. I will be working on a number of proposals that have to do with the use of the pharse "shall be permitted" which is, in my opinion, incorrectly used in a number of code sections. An example is 310.4.
Don
 
I understand exactly what y'all are saying, but have a different take on it.

Part I of Article 240 is GENERAL
Part II of Article 240 is LOCATION

240.4 says conductors shall be protected against overcurrent in accordance with their ampacities.

To me, this does indeed mean all conductors, ungrounded, grounded, and grounding. Now, notice that 240.4 does not say WHERE the overcurrent devices have to be LOCATED.

As an example, say we have a 120 volt circuit: Circuit breaker to ungrounded conductor to load to grounded conductor to neutral bar.

The grounded conductor is protected by the circuit breaker by virtue of the protection of the ungrounded conductor having an OCP device. I am also suggesting that any eguipment grounding conductors of the circuit are also protected by the circuit breaker.

Now, Part II of Article 240 talks about LOCATION of OCP.

240.21: This is where it says that fuses/breakers shall be installed in series with ungrounded conductors at their point of supply.

240.22: This says not to put OCP directly in series with the ungrounded conductor.

I don't really see an issue with this. Except, perhaps, there should be a section equivalent to 240.22 except applying to grounding conductors.
 
Pierre C Belarge said:
240.22 Grounded Conductor.

No overcurrent device shall be connected in series with any conductor that is intentionally grounded, unless one of the following two conditions is met;
(1) The overcurrent device opens all conductors of the circuit, including the grounded conductor, and is designed so that no pole can operate independently.
(2) Ehrt trwuitrf ny 430.36 or 430.37 for motor overload protection.
Click to expand...


What in the world is this???
Who Typed this, me? :grin: What was I smoking?
 
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