Multiple power source

[ceb58]

Here is the set up, every thing 120/240 single phase. Utility power into a ATS from service disconnect. ATS then supplies a MDP that runs lights, A/C and gen use recpts. also out of MDP it feeds a service switch with a UPS that powers a UPS panel that runs communication equipment.

Some one connected a piece of equipment in the UPS panel that should not have been. It should have been feed from the MDP. The guys that were sent to correct this wanted to just install another piece of conduit from the UPS panel to the MDP, make a splice in the panel and carry it to the MDP. I said that I did not think that was code due to the fact that the UPS panel had a separate power source aside from the normal utility or gen. power that the panel would receve from the MDP. Am I wrong on this?

 

[iwire]

Please don't keel me, but IMO you are mistaken.

 

[ceb58]

Please don't keel me, but IMO you are mistaken.

No prob Bob. not the first time wont be the last.
Please explane why I am wrong, Just want to know

 

[iwire]

No prob Bob. not the first time wont be the last.
Please explane why I am wrong, Just want to know

There is no rule in the NEC that I am aware of that prohibits multiple sources in one enclosure and many times it is common.

I once wired 480 volt GFP breakers that required an external source of 120 VAC to operate.

 

[ceb58]

There is no rule in the NEC that I am aware of that prohibits multiple sources in one enclosure and many times it is common.

I once wired 480 volt GFP breakers that required an external source of 120 VAC to operate.

Not trying to be a pain but.... In my mind I am thinking catastrophic mishap. If something were to interrupt utility power and gen. did not take over and there were a short in the UPS panel between the conductors it could back feed power to the MDP. I'M just thinking out loud.

 

[Pierre C Belarge]

As Bob mentioned, it is not a violation of the NEC.

If you are concerned about a short imposing itself onto the conductors, maintain some space between the conductors during the installation process.

 

[hurk27]

Don't have my NEC here right now, but something on the lines or circuit conductors of different sources needs identification comes to mind, and the neutral needs to be marked. 200.6(D) if my memory still serves me.
But as for ungrounded conductors, I can only remember a requirement for circuits of different voltages 210.4(D) I think
But I still mark any wire from other systems to where they originate

 

[Pierre C Belarge]

That info is fairly new. 200.6(D), 210.(5)(C) and 215.12(C)

 

[ceb58]

As Bob mentioned, it is not a violation of the NEC.

If you are concerned about a short imposing itself onto the conductors, maintain some space between the conductors during the installation process.

Thanks for the help guy's. We have over 200 communication sites all over the state. My self and one other guy are the only electricians for all of them, me being the only one licensed. (State agency so licensing is moot) The electronic techs do a lot of electrical installs, which I have found major violations. My boss doesn't like the mixing of power sources and I feel that even if it is not a violation it would be better not to do it. The electronic techs. are good at what they do with the communication equipment and I would not begin to try and understand some of the equipment they install and maintain. But from a safety stand point of some one not knowing what is going on inside these panels it would be best not to mix the different power sources except in thing like transfer switches.