Tap Rule ?

[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 OCPD outside near the TAP box for that 200 amp MB 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?

 

[jumper]

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 OCPD outside near the TAP box for that 200 amp MB 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?

I believe you need a full sized disconnect at the house. 225.31

I do not think you can use T310.15(B)(6) when sizing sub panels in residential. One main set of service conductors has to carry the full load when using this table.

 

[infinity]

You need to comply with 225.31 and 225.32.
For SE cable you would need to size the conductors according to the 60? ampacity in table 310.16 so your proposed conductor sizes are too small.

225.31 Disconnecting Means.
Means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure.
225.32 Location.
The disconnecting means shall be installed either inside or outside of the building or structure served or where the conductors pass through the building or structure. The disconnecting means shall be at a readily accessible location nearest the point of entrance of the conductors. For the purposes of this section, the requirements in 230.6 shall be utilized.
Exception No. 1: For installations under single management, where documented safe switching procedures are established and maintained for disconnection, and where the installation is monitored by qualified individuals, the disconnecting means shall be permitted to be located elsewhere on the premises.
Exception No. 2: For buildings or other structures qualifying under the provisions of Article 685, the disconnecting means shall be permitted to be located elsewhere on the premises.
Exception No. 3: For towers or poles used as lighting standards, the disconnecting means shall be permitted to be located elsewhere on the premises.
Exception No. 4: For poles or similar structures used only for support of signs installed in accordance with Article 600, the disconnecting means shall be permitted to be located elsewhere on the premises.