Another tap rule question

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darekelec

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nyc
I would like to tap 300 Amp from 800 Amp service switch that already has other loads. My tap conductors will have to pass thru electric meter and then go to 300 Amp fused switch.
Does 240.21 B(2) (2) limit me and I have to have my conductors less than 10 feet?

(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

Can one interpret this as immediately terminate - not pass thru anything f. e.g. meter
I guess not but I would not like to redo the install.
You guys are professionals.
Thank you and have a wonderful rest of weekend.
 
darekelec said:
load side.
Eagle, can I make it on line side?
Click to expand...
Maybe.
But if it is on the load side of the disconnect you cannot run it in the same raceway with service conductors that are on the line side.
Depending on local codes and POCO you may not be allowed to run from load side through a meter (unless it is a private rather than POCO meter.)
 
darekelec said:
I would like to tap 300 Amp from 800 Amp service switch that already has other loads. My tap conductors will have to pass thru electric meter and then go to 300 Amp fused switch.
Does 240.21 B(2) (2) limit me and I have to have my conductors less than 10 feet?

(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

Can one interpret this as immediately terminate - not pass thru anything f. e.g. meter
I guess not but I would not like to redo the install.
You guys are professionals.
Thank you and have a wonderful rest of weekend.
Click to expand...

When it says "terminate" it means where it is electrically connected to something else and has nothing to do with raceways or enclosures it passes through before it does "terminate".

That said and as others have hit on, you can not have service and non service conductors in the same raceway, wireway, aux gutter, the latter two can if there is a barrier installed effectively making them separate wireways or gutters. Also POCO may or may not allow additional conductors in the meter enclosure even if NEC does allow them.
 
If the service conductors are actually routed thru the meter cabinet, at 800 amps, I would think there are CTs in the cabinet also. Local POCOs use a CT cabinet that has terminals.
I think my first stop would be with POCO to see if they already have a point in the meter cabinet where you can connect and also see what their take is on routing thru their cabinet.
 
Metering is done in this matter in all the basement - 4 stores, house panel and a lot of apartments after 800 amp service switch. I assume the POCO will tell me to stick with this manner.
My concern is if I can have my conductors 10 feet or 25 feet as per 240.21
Existing tap conductors to mentioned stores and apartments from SS are somewhere between 5 and several feet but they were installed when nyc was very tolerant about nec so I cannot use that as a guide.
I can run my 300 amp taps on top (more tan 10 feet - less work) or under slab (less that 10 feet - much more work).
what bothers me is interpretation of 240.21 B(2) (2)
 
darekelec said:
Metering is done in this matter in all the basement - 4 stores, house panel and a lot of apartments after 800 amp service switch. I assume the POCO will tell me to stick with this manner.
My concern is if I can have my conductors 10 feet or 25 feet as per 240.21
Existing tap conductors to mentioned stores and apartments from SS are somewhere between 5 and several feet but they were installed when nyc was very tolerant about nec so I cannot use that as a guide.
I can run my 300 amp taps on top (more tan 10 feet - less work) or under slab (less that 10 feet - much more work).
what bothers me is interpretation of 240.21 B(2) (2)
Click to expand...

(B)(2)(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
Click to expand...

It says the conductors must end in a single overcurrent device rated no more than the ampacity of the conductors. In your case you are wanting to tap 300 amps. If you make this tap to a 300 amp overcurrent device then the conductors must have an ampacity of 300 amps. A conductor with an ampacity of say 285 (300kcmil copper)can not use the next standard size up rule in this instance even if the connected load is less than 285. So minimum copper conductor would need to be 350kcmil, plus meet the other requirements of (B)(2).
 
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