Quad receptacles fed from two 120V panels

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IL94EE

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I'm an electrical engineer doing a peer review of a design from another firm. Without getting into too much detail or giving any security information away, it's an Air Force building with a number of offices and workstations which require power from both normal utility and from a UPS system because whatever is plugged into them can't just shut off if the power drops. The engineer doing the design is showing quadplex receptacles (two duplexes in the same box) with a UPS circuit to one duplex and a normal circuit to the other duplex. I haven't been able to put my finger on a specific code reference reason this is not acceptable, but it just screams at me that this can't be done. At the very least, it's a safety hazard to come from two different panels like that. Can anyone point me definitively to where the code prohibits this, or is it totally acceptable?
 
I am not an expert on this but if they don't share the same yolk then I don't believe it is an issue. Ups is mentioned in many articles but not sure what would apply here since we don't know what it is used for. Not sure it would matter either.

Hang on someone is bound to know for certain
 
Unless one of the circuits is an emergency circuit there is nothing wrong with two panels serving two receptacles in one box. If safety is a concern install a barrier in the box.
 
Sounds like a Legally Required circuit.

Allowed.

701.10 Wiring Legally Required Standby Systems. The legally required standby system wiring shall be permitted to occupy the same raceways, cables, boxes, and cabinets with other general wiring.
 
One possible issue would be if the adjacent devices had more than 300 volts between them, not sure if that's even possible with 120 volt receptacles from different systems. :)
 
None of it is legally required/emergency circuiting. It's just UPS power for computers and such which "can't go down". The voltage level between devices shouldn't be an issue either. So maybe it's not a code violation, but it just sounds like a recipe for someone to get shocked. Thanks.
 
IL94EE said:
None of it is legally required/emergency circuiting. It's just UPS power for computers and such which "can't go down". The voltage level between devices shouldn't be an issue either. So maybe it's not a code violation, but it just sounds like a recipe for someone to get shocked. Thanks.
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NEC code is bare minimum.


NEC 90.1 has four subdivisions:


  • (A) says the purpose of the NEC is the practical safeguarding of people and property "from hazards arising from the use of electricity."
  • (B) distinguishes from the adequacy concept (provisions necessary for safety) and other concepts. The Code is a minimum standard. Further effort may be required for an installation to be efficient, convenient, or adequate for good service or future expansion. This is a fundamental concept upon which many Code disagreements arise. The Code is not a target you’d like to hit. It is the minimum you can do.
  • (C) clearly states the Code is not intended to be a design specification or instruction manual.








IL94EE
I'm an electrical engineer doing a peer review of a design from another firm. Without getting into too much detail or giving any security information away, it's an Air Force building with a number of offices and workstations which require power from both normal utility and from a UPS system because whatever is plugged into them can't just shut off if the power drops. The engineer doing the design is showing quadplex receptacles (two duplexes in the same box) with a UPS circuit to one duplex and a normal circuit to the other duplex. I haven't been able to put my finger on a specific code reference reason this is not acceptable, but it just screams at me that this can't be done. At the very least, it's a safety hazard to come from two different panels like that. Can anyone point me definitively to where the code prohibits this, or is it totally acceptable?



building with a number of offices and workstations which require power from both normal utility and from a UPS system because whatever is plugged into them can't just shut off if the power drops.

Somewhat Fail Safe?.....

Is there any chance of a What IF happens if the two systems are installed in the same box and conduit?

I can't ever recall seeing UPS power installed in the same conduit and or box with normal power.

Jim
 
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