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发表于 2014-3-24 16:45:38
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本帖最后由 北方郎 于 2014-3-24 16:48 编辑
回复 20# 治学以诚
NFPA 70-2011National Electrical Code
210.10 Ungrounded Conductors Tapped from GroundedSystems.
Two-wire dc circuits and ac circuits of two or more ungrounded conductors shall be permitted to be tapped from the ungrounded conductors of circuits that have a grounded neutral conductor. Switching devices in each tapped circuit shall have a pole in each ungrounded conductor. All poles of multipole switching devices shall manually switch together where such switching devicesalso serve as a disconnecting means as required by the following:
(1) 410.93 for double-pole switched lampholders
(2) 410.104(B) for electric-discharge lamp auxiliary equipment
switching devices
(3) 422.31(B) for an appliance
(4) 424.20 for a fixed electric space-heating unit
(5) 426.51 for electric deicing and snow-melting equipment
(6) 430.85 for a motor controller
(7) 430.103 for a motor
貌似此处为局部TT系统,也可以用哈。 |
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