Any ungrounded conductors that supply, or pass through, a structure must have a means of being disconnected [225.31]. But where do you put the disconnecting means?
It must be:
1. Inside or (immediately) outside the structure being served [225.32].
2. At a readily accessible location near the point where the conductors enter the structure.
Four exceptions apply to the rules just stated. The disconnects can be elsewhere on the premises in any of the following situations:
1. The installation is under single management, documented safe switching procedures are established and maintained for disconnection, and qualified individuals monitor the installation.
2. The structure qualifies under the provisions of Art. 685 (Integrated Electrical Systems).
3. The installation is a tower or pole used as a lighting standard.
4. The installation is a pole or similar structure used only to support signs installed per Art. 600.
You can’t have more than six disconnects per supply, grouped in any location [225.33]. But an exception applies; if the disconnect is solely for the control circuit of the ground-fault protection system or the power-operated supply disconnecting means, it doesn’t count toward the limit of six.
