25 Foot tap rule on residential job

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tortuga

tortuga

Code Historian
Location
Oregon
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Electrical Design
I dont often see feeder taps on residential and am considering using one.
The property has 2 single family dwellings. One existing and one now being built. On the new dwelling there is an attached shop / garage.
For logistical reasons the existing dwellings service is changing to a feeder and being moved to be fed underground from the ADU.
On the ADU there will be a 3 pack meter center with 2 200A mains. The 3rd meter / feeder is a 100A to the shop / garage space so it could be a common area if both units were separate rentals. Since the owner is living in the existing dwelling he would like the shop on his house meter to avoid the 2nd meter fee.

There is about a 20 foot run of PVC from the meterpack to the 100A main breaker panel in the shop mostly under concrete slab. I am considering making a tap off the 200A existing house feeder in the meter pack for the 100A panel.
The tap conductors would be #3 CU and not more than 25 feet long to the 100A main.
When the home owner moves it would be a service call to undo the tap and land the wires on the 100A main in the meter center.
There is plenty of room in the meter center for a tap, but since this is not installed yet I could do something different.

Is this code? I think the reference is 240.21(B)(2). Is there anything somewhere else that blocks this on residential?
Thanks in advance
 
How about using jumpers in the 100A meter. I've seen the local utility use specific metal bars to jump a meter temporarily when a very old SEC burned through one leg on the side of a stone house. The utility came out in the mid of the night and jumped the meter with bars putting all loads on the good leg.

Or, you can buy a utility style meter and pop it in...not cheap.
 
conmgt said:
How about using jumpers in the 100A meter. I've seen the local utility use specific metal bars to jump a meter temporarily when a very old SEC burned through one leg on the side of a stone house. The utility came out in the mid of the night and jumped the meter with bars putting all loads on the good leg.

Or, you can buy a utility style meter and pop it in...not cheap.
Click to expand...

If you jump a meter you will be placing the load ahead of the other meters, this would have the load as un-meterd and would be utility theft.



To the OP

Is there a reason you can't install a single meter on each dwelling, I would think it would be much cheaper then installing a multiple meter pack and using feeders?? also if the property is ever sold as separated in the future it would all have to be changed to separate services.

Also if you install a single meter you can take advantage of 230.40 exception 3 by using a 320 meter with double lugs on the load side of the meter and feeding the garage with a 3 conductor cable as allowed because they are service entrance conductors, you won't even need a disconnect for the garage at the house for the same reason as they do not enter the house, all you do is install a main breaker panel at the garage and a grounding electrode system as code would require anyways for a separate building, and since your on the load side of the meter at the house you don't need a meter at the garage.

Also if the existing service for the existing dwelling is a main breaker panel then you would have to relocate the existing grounding electrodes to the new meter pack, as well as separate all the grounding and neutrals and remove the neutral to ground bond in this existing panel, by using the above method this would not have to happen.

Also if you feed the new dwelling from a meter pack on the existing dwelling you will still have have a main breaker panel or disconnect at the new dwelling as well as its own grounding electrode system.

If you are up sizing the existing service for the garage load the 320 meter will take care of that as you can supply the existing service with 100 amps and the garage with a 100 amps, you could also use a tap box below the meter with a 200 amp meter base to do the same thing or locate a 200 amp meter base with the ability to use double lugs on the load side, I think Mid-West used to offer one.

Check with your local or state AHJ as some might not like this way of feeding a garage but it is and has always been allowed by the NEC.

Also check out this thread for more info as the thread starter had an AHJ trying to reject his use of 230.40 exception 3 buy saying the disconnects had to be grouped.:

This thread
 
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