[RE-wrenches] Feeder without a dedicated breaker

[William Miller]

Dan:

As I read it, the ampacity of the wire need only be 1/3 of the OCP.  And 
yes, the OCP for this tap is the 200 amp main, although it can be construed 
that the circuit breaker at the down-stream end of the feeder provides 
protection as well (if you short the bus the feeder is supplying, the 
down-stream CB prevents the feeder from melting due to the 3X ampacity of 
the upstream protection).

Also at issue is the question: is the romex wire protected "by other 
means"?  Judgement call.

See citation below from 240.21(B):

(2) Taps Not over 7.5 m (25 ft) Long. Where the length of
the tap conductors does not exceed 7.5 m (25 ft) and the tap
conductors comply with all the following:
(1) The ampacity of the tap conductors is not less than
one-third of the rating of the overcurrent device protecting
the feeder conductors.
(2) The tap conductors terminate in a single circuit breaker
or a single set of fuses that limit the load to the ampacity
of the tap conductors. This device shall be permitted
to supply any number of additional overcurrent devices
on its load side.
(3) The tap conductors are protected from physical damage
by being enclosed in an approved raceway or by other
approved means.

End of citation

William Miller







At 01:06 PM 10/25/2011, you wrote:
>William,
>
>The tap conductor ampacity must not be less than the rating of the breaker
>protecting that circuit, which in this case (if I understand the configuration
>correctly) would be the main breaker in the panelboard.
>
>Any smaller gauge would require its own OCP device of appropriate rating
>if it's to be code-compliant.
>
>Dan
>
>
>
>--- On Tue, 10/25/11, William Miller <william at millersolar.com> wrote:
>>
>>From: William Miller <william at millersolar.com>
>>Subject: Re: [RE-wrenches] Feeder without a dedicated breaker
>>To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
>>Date: Tuesday, October 25, 2011, 2:54 PM
>>
>>Jamie:
>>
>>Thanks for getting me started.  I did not think to consider this as a 
>>tap, but it appears to match the criteria.
>>
>>William Miller
>>
>>
>>
>>At 11:38 AM 10/25/2011, you wrote:
>>>William, I would start with Article 240.21(B).
>>>
>>>Jamie Johnson
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Miller Solar
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email: william at millersolar.com
http://millersolar.com
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