External Power - Orange wire

alexbeatle

Member
Join Date
Feb 2010
Location
San Francisco
Posts
188
Hello folks,

Trying to understand wiring rules for the PLC cabinet. Per NFPA79 13.2.4.1:
"The colour ORANGE shall be used to identify ungrounded conductors that remain energized when the main supply circuit disconnecting means is in the off position...."

If I have an orange 120VAC wire coming into a cabinet and landing on 24VDC power supply on the line side, should all the load wire of the 24VDC power supply be also orange in colour? Technically those will remain energised.

Thanks in advance.
 
I never did but I also put a label on the outside and inside of the panel noting that there is a second power source, I guess it would not hurt if its feeding a bus to note it there also.... I never once said "This guy put too many identifiers/labels in this cabinet"
 
We would never supply any equipment form outside of the cabinet without isolation but the exception was of interfaces, these were identified by orange wiring and were isolated via relays or opto isolation and placed in a separate enclosure within the cabinet with warning signs of isolation elsewhere.
 
No, because the SOURCE for that 24VDC is INSIDE of your panel, the power supply. Yes, it will remain energized even if the main disconnect it, but you can simply turn off the power supply with a breaker or pull a fuse and it is no longer energized. You can't turn off the 120V circuit coming into the panel from WITHIN the panel though.
 
No, because the SOURCE for that 24VDC is INSIDE of your panel, the power supply. Yes, it will remain energized even if the main disconnect it, but you can simply turn off the power supply with a breaker or pull a fuse and it is no longer energized. You can't turn off the 120V circuit coming into the panel from WITHIN the panel though.

It's also good to have a Sequestr Disconnects and put that 24VDC supply in there.
 
I never did but I also put a label on the outside and inside of the panel noting that there is a second power source, I guess it would not hurt if its feeding a bus to note it there also.... I never once said "This guy put too many identifiers/labels in this cabinet"

+1 +1 +1
The 'there are external power sources' label is really informative if it tells the person who is reading the label where THAT power comes from.
In the USA, this should be addressed in the written Tag Out Log Out plan, to be in compliance with OSHA 1910.147, of course.
{Everybody has a tag out lock out plan, right?}
:geek:
 

Similar Topics

Hello everyone, I have a PLC question, in regards to using several external 24 VDC power supplies, from different machines ! I only have (2)...
Replies
4
Views
3,494
Hi, I have encountered a problem with PLC and DCS I/O card power supply requirement for field wiring. Do PLC and DCS card both need external...
Replies
0
Views
3,838
Hi all... need solution for this case..I have signed 1 Ea Gas detector ( use External power +24Vdc) to DCS Yokogawa. before it, 4 ea Gas Detector...
Replies
4
Views
4,030
Hi all, I'm new to Siemens and looking to use an s7 with 3 racks. I have one simple question, does the im361 require external power, or does...
Replies
4
Views
4,209
I am trying to enable an external alarm via computer speakers for Factory Talk Network Distributed Edition. I am using Alarm and Events setup. I...
Replies
7
Views
126
Back
Top Bottom