Tap Rule ? - Electrician Talk - Professional Electrical Contractors Forum

Xknob&Tube · 04-23-2010, 12:10 AM

I have an existing 250 amp fused disconnect on a detached garage where the meter is. I will run #300 URD to house about 50 feet away. There, I would like to set a gutter outside to TAP to a 125 amp MB panel nearby (just on the other side of the wall inside the garage) and also TAP to a 200 amp MB panel in the basement about 30 feet away.

1. Must I put a 200 amp OCD outside near the TAP box for that 200 amp panel?

2. Can I use #1/0 AL SER cable for the 125 amp panel?

3. Can I use #4/0 AL SER for the 200 amp panel?

JohnJ0906 · 04-23-2010, 06:58 PM

Quote:

Originally Posted by Xknob&Tube

I have an existing 250 amp fused disconnect on a detached garage where the meter is. I will run #300 URD to house about 50 feet away. There, I would like to set a gutter outside to TAP to a 125 amp MB panel nearby (just on the other side of the wall inside the garage) and also TAP to a 200 amp MB panel in the basement about 30 feet away.

You will need disconnecting means for that feeder - 225.31, 225.32, 225.34

Quote:

1. Must I put a 200 amp OCD outside near the TAP box for that 200 amp panel?

Yes, 30' is too long - 240.21, as well as the disconnecting means requirement.

Quote:

2. Can I use #1/0 AL SER cable for the 125 amp panel?

3. Can I use #4/0 AL SER for the 200 amp panel?

IMO, no to both - 310.15(B)(6) doesn't apply, because neither is the main feeder serving the dwelling.

Your best bet may be to run the feeder into a trough, do your taps there to (2) disconnects, a 125 and a 200, and then run the feeders to the 2 individual panels.

You will have to use table 310.16 to size your feeders.

Nephi · 04-23-2010, 07:13 PM

1. yes
2. yes
3. yes

Xknob&Tube · 04-23-2010, 11:00 PM

Quote:

IMO, no to both - 310.15(B)(6) doesn't apply, because neither is the main feeder serving the dwelling.

Wouldn't 310.15(B)(6) feeder definition be valid here because it is the feeders feeding the house from the fused (main) disconnect at the meter at the garage?:

Table 310.15(B)(6), shall be permitted as
120/240-volt, 3-wire, single-phase service-entrance conductors,
service-lateral conductors, and feeder conductors
that serve as the main power feeder to each dwelling unit
and are installed in raceway or cable with or without an
equipment grounding conductor. For application of this section,
the main power feeder shall be the feeder between the
main disconnect and the panelboard that supplies, either by
branch circuits or by feeders, or both, all loads that are part
or associated with the dwelling unit.

Also, because the 125 amp panel is less than 10 feet away (240.21) I do not need a OCD at the tap location (the MB on the panel is required)?
Thanks for the help, I've never done a service like this before

kwired · 04-24-2010, 01:17 AM

Quote:

Originally Posted by Xknob&Tube

I have an existing 250 amp fused disconnect on a detached garage where the meter is. I will run #300 URD to house about 50 feet away. There, I would like to set a gutter outside to TAP to a 125 amp MB panel nearby (just on the other side of the wall inside the garage) and also TAP to a 200 amp MB panel in the basement about 30 feet away.

1. Must I put a 200 amp OCD outside near the TAP box for that 200 amp panel?

2. Can I use #1/0 AL SER cable for the 125 amp panel?

3. Can I use #4/0 AL SER for the 200 amp panel?

240.21

Quote:

(5) Outside Taps of Unlimited Length. Where the conductors are located outdoors of a building or structure, except at the point of load termination, and comply with all of the following conditions:
(1) The conductors are protected from physical damage in an approved manner.
(2) The conductors terminate at a single circuit breaker or a single set of fuses that limit the load to the ampacity of the conductors. This single overcurrent device shall be permitted to supply any number of additional overcurrent devices on its load side.
(3) The overcurrent device for the conductors is an integral part of a disconnecting means or shall be located immediately adjacent thereto.
(4) The disconnecting means for the conductors is installed at a readily accessible location complying with one of the following:
a. Outside of a building or structure
b. Inside, nearest the point of entrance of the conductors
c. Where installed in accordance with 230.6, nearest the point of entrance of the conductors

You can run taps unlimited lengths outdoors if you follow proper conditions.

Are the two panels in question serving the same building if so then you must have disconnects grouped together.

Quote:

225.34 Grouping of Disconnects.
(A) General. The two to six disconnects as permitted in 225.33 shall be grouped. Each disconnect shall be marked to indicate the load served.

Xknob&Tube · 04-24-2010, 05:52 PM

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Are the two panels in question serving the same building if so then you must have disconnects grouped together.

Thanks, I forgot about that (something I never consider for a single family residence)

Quote:

Your best bet may be to run the feeder into a trough, do your taps there to (2) disconnects, a 125 and a 200, and then run the feeders to the 2 individual panels.

I'll do it this way...thanks for all your help! http://www.electriciantalk.com/image...es/biggrin.gif