Tap Conductor Rules

Feeders Can Be Tapped Under The Following Conditions 10 Foot Tap Rule Art. 240.21.b.1.1 MAIN RULE:The Overcurrent Device Must Be Located At The Point Where The The Conductor Receives Its Supply Feeders Can Be Tapped Under The Following Conditions 1. Not Over 10 feet 2. Not Less Than The Combined Loads, Ampere Ratings of Switchboards , Panelboards, or Control Devices. 3. Termination Is Not Made Beyond the Switchboard, Panel or Control Device 4. Conductors Must Be Protected Form Damage 5. Tap Conductor Ampacity Not Greater Than 10 times The Overcurrent Device.

Tap Conductors 10 Feet or Less Article 240.1.b.1 Minimum size secondary conductors Article 240.21.B.1 3m (10) ft Tap Rules

Feeders Can Be Tapped Under The Following Conditions 25 Foot Tap Rule Art. 240.21.b.1.1 MAIN RULE:The Overcurrent Device Must Be Located At The Point Where The The Conductor Receives Its Supply Feeders Can Be Tapped Under The Following Conditions 1. Not Over 25 feet 2. Not Less Than The Combined Loads, Ampere Ratings of Switchboards , Panelboards, or Control Devices. 3. Termination Is Not Made Beyond the Switchboard, Panel or Control Device 4. Conductors Must Be Protected Form Damage 5. Tap Conductor Ampacity Not Less Than 1/3 the size of the Overcurrent Device.

Overcurrent Protection Transformer Primary Plus Secondary Conductors Article 240.21(C)(5) Tap Conductor Ampacity Must Be At Least One Third Of The OCPD Secondary Conductors Cannot Be Over Ten Feet (3) Taps Supplying a Transformer [Primary Plus Secondary Not Over 7.5 m (25 ft) Long]. Where the tap conductors supply a transformer and comply with all the following conditions: (1) The conductors supplying the primary of a transformer have an ampacity at least one-third the rating of the overcurrent device protecting the feeder conductors. (2) The conductors supplied by the secondary of the transformer shall have an ampacity that, when multiplied by the ratio of the secondary-to-primary voltage, is at least one-third of the rating of the overcurrent device protecting the feeder conductors. (3) The total length of one primary plus one secondary conductor, excluding any portion of the primary conductor that is protected at its ampacity, is not over 7.5 m (25 ft). (4) The primary and secondary conductors are suitably protected from physical damage. (5) The secondary conductors terminate in a single circuit breaker or set of fuses that limit the load current to not more than the conductor ampacity that is permitted by 310.15. (2) Transformer Secondary Conductors Not Over 3 m (10 ft) Long. Where the length of secondary conductor does not exceed 3 m (10 ft) and complies with all of the following: (1) The ampacity of the secondary conductors is a. Not less than the combined computed loads on the circuits supplied by the secondary conductors, and b. Not less than the rating of the device supplied by the secondary conductors or not less than the rating of the overcurrent-protective device at the termination of the secondary conductors (2) The secondary conductors do not extend beyond the switchboard, panelboard, disconnecting means, or control devices they supply. (3) The secondary conductors are enclosed in a raceway, which shall extend from the transformer to the enclosure of an enclosed switchboard, panelboard, or control devices or to the back of an open switchboard. FPN: For overcurrent protection requirements for lighting and appliance branch-circuit panelboards and certain power panelboards, see 408.16(A), (B), and (E). (5) Secondary Conductors from a Feeder Tapped Transformer. Transformer secondary conductors installed in accordance with 240.21(B)(3) shall be permitted to have overcurrent protection as specified in that section.

Transformer Secondary Conductors Article 240.21.b.3

Example 250 Amp Overcurrent Tap Conductors Protection Device ( Circuit Breaker) Tap Conductors Ampacity of these conductors is 40 amps

Tap conductors – 40 amps of ampacity Circuit Breakers 250 Amp Circuit Breaker