ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals

>> Home   >> Electrical-Photos   >> Classifieds   >> Subscribe to Newsletter   >> Store  
 

Photos of the Week:

1923 Los Angeles Wireman's Handbook
1923 LA Wiremans Hbk

Random Gallery Image:
Recent Gallery Topics:
What in Tarnation?
What in Tarnation?
by timmp, September 10
Plumber meets Electrician
Plumber meets Electrician
by timmp, September 10
Who's Online Now
0 members (), 342 guests, and 25 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Joined: Aug 2004
Posts: 1
J
Junior Member
I'm building a heater temperature control system in one enclosure for a customer. The customer requested that they will supply the enclosure with a 120VAC single phase 10A control power and 480VAC 3-phase 30A power for the heater. Does the NEC require any warning signs be posted on the outside of the enclosure to notify the user that the system is supplied by two power sources?

Horizontal Ad
Joined: Apr 2002
Posts: 2,527
B
Moderator
That is one reason why MCC cubicles {buckets} and combination starters are available with 480:120V control-power transformers — to limit hazardous/foreign voltages [below the disconnect line terminals] when the disconnect is opened.

Joined: Oct 2000
Posts: 2,749
Member
Research Article 424, and see this because the logic is considered:

Quote
430.113 Energy from More Than One Source.

Motor and motor-operated equipment receiving electrical energy from more than one source shall be provided with disconnecting means from each source of electrical energy immediately adjacent to the equipment served.

Each source shall be permitted to have a separate disconnecting means. Where multiple disconnecting means are provided, a permanent warning sign shall be provided on or adjacent to each disconnecting means.

Exception No. 1: Where a motor receives electrical energy from more than one source, the disconnecting means for the main power supply to the motor shall not be required to be immediately adjacent to the motor, provided the controller disconnecting means is capable of being locked in the open position.

Exception No. 2: A separate disconnecting means shall not be required for a Class 2 remote-control circuit conforming with Article 725, rated not more than 30 volts, and that is isolated and ungrounded.


Joe Tedesco, NEC Consultant
Joined: Jul 2003
Posts: 394
B
Member
In my industrial facility, we were required by OSHA to post signs on our panels indicating Dual Voltages and Multiple Voltages where that applied.


Link Copied to Clipboard
Advertisement:-Right


Tools for Electricians
Tools for Electricians
 

Member Spotlight
SafetyWired
SafetyWired
Pa, USA
Posts: 44
Joined: July 2013
Top Posters(30 Days)
Admin 3
Popular Topics(Views)
366,161 Are you busy
289,017 Re: Forum
267,595 Need opinion
New Page 2
Powered by UBB.threads™ PHP Forum Software 7.7.5