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Illustrated Changes to the NEC, 2005 Edition - Part 1

Article 210

Branch Circuits

210.4 Multiwire Branch Circuits

Part I. General Provisions

New FPN alerts the Code user to ensure that the continuity of the grounded neutral conductor of a multiwire circuit isnít interrupted (open), because doing so can result in a fire and/or destruction of electrical equipment because of under- or over-voltage.

(C) Line-to-Neutral Loads. Multiwire branch circuits must supply only line-to-neutral loads.
Ex 1: A multiwire branch circuit is permitted to supply line-to-line utilization equipment, such as a range or dryer.

Ex 2: A multiwire branch circuit is permitted to supply both line-to-line and line-to-neutral loads if the circuit protection device opens all ungrounded conductors of the multiwire branch circuit simultaneously under a fault condition (multipole circuit breaker with common internal trip). Figure 210-1

FPN: See 300.13(B) for the requirements relating to the continuity of grounded neutral conductor on multiwire circuits.

CAUTION: If the continuity of the grounded neutral conductor of a multiwire circuit is interrupted (open), the resultant over- or undervoltage could cause a fire and/or destruction to electrical equipment. Figure 210-2


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