leitmotif
Member
OK some background
In the Navy just about all equipment used 440 (or 250DC for DC equipment) for control power. 440 was obtained from two of 3 phases.
I have also in civilian world seen 125 (and I believe 250 DC) for control power at Trojan Nuclear plant. But this was for switchgear control only not motors if I recall correctly.
Now I know the NEC excludes shipboard and utilities.
I also like the idea of low voltage ie 120 or less control power ESPECIALLY with ground referenced wiring. A ground on 220 or 440 control circuit could be enough to energize the contactor. That would be the SxxTS if you thought it was turned off.
BUT the question is this
Who says I gotta use 120 or less for control power?
I cant find it in NEC - would it be NFPA 70??
If I recall correct NFPA 70 is Electrical Worker Safety.
Is there not another NFPA "chapter" for motor control?
I'm doing this at home, and I do not have a set of NFPA at work much less home.
Could someone tell me the book and IF they got a few minutes give the chapter # and a quote where it says "thou SHALT"
Thanks
Dan Bentler
In the Navy just about all equipment used 440 (or 250DC for DC equipment) for control power. 440 was obtained from two of 3 phases.
I have also in civilian world seen 125 (and I believe 250 DC) for control power at Trojan Nuclear plant. But this was for switchgear control only not motors if I recall correctly.
Now I know the NEC excludes shipboard and utilities.
I also like the idea of low voltage ie 120 or less control power ESPECIALLY with ground referenced wiring. A ground on 220 or 440 control circuit could be enough to energize the contactor. That would be the SxxTS if you thought it was turned off.
BUT the question is this
Who says I gotta use 120 or less for control power?
I cant find it in NEC - would it be NFPA 70??
If I recall correct NFPA 70 is Electrical Worker Safety.
Is there not another NFPA "chapter" for motor control?
I'm doing this at home, and I do not have a set of NFPA at work much less home.
Could someone tell me the book and IF they got a few minutes give the chapter # and a quote where it says "thou SHALT"
Thanks
Dan Bentler