This is one of my first assignments as a co-op. I need to figure out what size SO cord to use to supply 460VAC at a 72A full load current. the total distance from 100 amp wall mounted disconnect to control panel/machine is about 75 feet. I looked in the NEC book and based on 100 amps (over estimate) the conductor size needs to be 3 AWG. Looking online, I find SO cord based on voltages and not current. I also need quick connects. I didn't know you needed quick connects when connecting power cord to breakers. Apparently I don't know enough about power, I'm excellent with coding though. Any information is appreciated. thanks.
power cord
- Thread starter hurt33
- Start date
- Status
Cold Fusion
Senior Member
- Location
- way north
First Q: 3ph? 3W, 4W, 5W?
Second Q: Where in the NEC did you see 100A rating for SO cord? Look at T400.5.A and B. For 3phase, #2 SO cord is only good for 80A.
Requirements for attachment plugs is in 400.7.B. The application may require quick connects. The code may not. Could be a design issue.
Crouse-Hinds, appleton make pin and sleeve plugs and and receptacles. Amazingly the C-H 100A plug will not take a 4C-#2 SO. The sheath is too big. Look at T400.5.B, type G or W, 75C, column F. #6 is good for 77A, #4 is good for 101A. For these types of applications, I've found G or W to be a better fit.
Several of the wire mfgs will have spec sheets on the web.
cf
Cold Fusion
Senior Member
- Location
- way north
It's a lot easier if you take a class the first time, from a good instructor. It's hard to pick up the cross connections (references) the first time through - and there are a lot. Unfortunately you won't know if the instructor is any good until you have taken three or four classes from different instructors.
The code panel members that write the NECs are not paid for their work. They use a unique form of english called "obscuritus confundus." I think it is revenge for not getting paid and having a bunch like me that regularly throw insults at them for their occasional lack of any sane connection to any known science or physics.
Never forget the NEC is written to get state governments to incorporate it into the state statues. It is a legal document made up of minimum that might work and shouldn't burn the palce down. The NEC is not a design guide.
All that aside, if I am not familiar witha particular installation method, I tend to ask the electricians, "What's a normal method to do this?" The good ones will be a bit surprised, but will answer - and that is always appreciated.
cf
- Status