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Double locknuts required? #88891
08/05/04 01:32 PM
08/05/04 01:32 PM
B
Bill39  Offline OP
Member
Joined: Nov 2001
Posts: 75
Indianapolis, IN, USA
Are 2 or 4 locknuts required if I use a RMC close nipple in this situation:

Two small dry-type tranformers are bolted together (back-to-back) and a close nipple used a a raceway between the transformers. There is about a 3/4 inch gap between them, which is too long for a chase nipple. A ground wire is pulled between the two transformers and terminated properly. Article 250.97 does not apply because the voltage is only 120vac to ground (230 phase to phase). Insulated bushings are required because the wire size is #2AWG.

2017 / 2014 NEC & Related Books and Study Guides
Re: Double locknuts required? #88892
08/05/04 02:05 PM
08/05/04 02:05 PM
E
electricman2  Offline
Member
Joined: Nov 2003
Posts: 269
Thomasville, NC USA
I would say 4 unless you devise some sort of spacer. Otherwise you wouldn't be able to properly tighten up the locknuts without distorting the transformer case.


John
Re: Double locknuts required? #88893
08/05/04 03:04 PM
08/05/04 03:04 PM
C
cpal  Offline
Member
Joined: May 2004
Posts: 162
Cohasset MA
Many manufactures produce metal bushings with insulated throats. these satisfy the requirements of 300.4 F . These types of bushings also have a serrated face that will grip like locknuts.

in situations not requiring double locknuts ( over 250V ), one of these bushings on the inside and a locknut on the outside should do it


charlie P


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