Is my new install legal?

darekelec

Senior Member
Location
nyc
I am trying to tap 300 amps from 800 amp service switch. I do not know if that conforms with tap rules. Especially with
240.21 (B) (2) Taps Not over 7.5 m (25 ft) Long.
(2) The tap conductors terminate in a single circuit breaker


  1. I am only concerned about my new install as basement is full of violations. There was no meeting yet with POCO but my boss assumes that metering will be required in this fashion because it is done like this in all basement.
    Is my new install NEC compliant?
    I asked this same question some time ago on this forum but I did not express myself clearly ,I think, and did not get black and white answer. 1 blueprint is a 1000 words.
    http://forums.mikeholt.com/showthread.php?t=157153
    What do you think?
    Thank you in advance for input.




 

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GoldDigger

Moderator
Staff member
I am trying to tap 300 amps from 800 amp service switch. I do not know if that conforms with tap rules.
What do you think?
Thank you in advance for input.
If the service switch is also an 800A overcurrent device, and the only OCPD on your new wiring is a 300A main in the new panel, then you have a tap. The conductors would have to be large enough to be protected by that 300A OCPD, and meet the other length and size requirements for the appropriate type of tap.
If you have a 300A MLO panel, and are relying on the sum of the branch breakers from that panel to protect tap wires, then you do not meet the rules that allow up to 7.5 meters.
Once you put the meter base into the picture, without OCPD before it you also lose the application of that set of tap rules. The meter base has a current limit also and is not protected in any way except at the 800A level. Even if the meter base can handle 800A, you have still "tapped a tap" to continue on to the panel.
If you use a 300A OCPD before the meter and an MLO panel after it, you should be OK, provided the rest of the applicable tap rules are met.
 
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david

Senior Member
Location
Pennsylvania
If the 800 amp switch is a service disconnect that would imply it has over current protection. If the 800 amp switch is your service location than the rest are feeders.
How do you unbound the neutral in your meter base?
 

david

Senior Member
Location
Pennsylvania
The OP said he was only concerned with the new installation to the new 300 amp panel in the basement for the store. Are you saying the feeder?s neutral to the new panel can bond to the meter enclosure?
 
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