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Joined: Feb 2004
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If a circuit supplies a fluorescent, mercury or metal halide do the neutrals still have to be counted as current carrying? This neutral will carry a third harmonic.
Thanks for any replies
Greg
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Joined: Aug 2003
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Yes, any non-linear(harmonic) load creates a current carrying nuetral.
Ryan Jackson,
Salt Lake City
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Joined: Nov 2000
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Only on 3 phase systems.
Don
Don(resqcapt19)
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Joined: Oct 2000
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... and only when that nonlinear load is the major portion (over 50%) ....
See the 2005 NEC .....
Nonlinear Load. A load where the wave shape of the steady-state current does not follow the wave shape of the applied voltage.
Article 310
(c) On a 4-wire, 3-phase wye circuit where the major portion of the load consists of nonlinear loads, harmonic currents are present in the neutral conductor; the neutral shall therefore be considered a current-carrying conductor.
FPN: Electronic equipment, electronic/electric-discharge lighting, adjustable-speed drive systems, and similar equipment may be nonlinear loads.
Joe Tedesco, NEC Consultant
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Joined: Jul 2004
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You can still induce out of phase currents in a single phase neutral (multiwire circuit) but you won't get the overload effect you get in 3 phase. It can still make measurememnts not balance if your meter isn't true RMS.
Greg Fretwell
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Lostazhell
Bakersfield, CA (Originally Orange Co.)
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