Multiple Voltage in One Box

[SpencerSpe]

We are involved in a remodel of a retirement home. The architect has decided to put all the switches in one location in a four gang configuration. We have found that some of the lights are 277 volts others are 120 volt. The voltages are in separate conduits. Does this break code?

 

[texie]

See 404.8 (B)

 

[mikeames]

Many threads on it. Someone did the math on all the possible combinations, but I cant find it.

404.8(b)

Can someone explain this in normal language. Is this from different systems or from the same panel? Is this for toggle switches and the like. Really confused.

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Voltage Between Adjacent Devices

On Page 157 of Mike Holt's "Changes to the NEC 2008" is a picture of a 277V circuit feeding a switch and a 120V circuit feeding a receptacle in the same device box. According to the illustration, the voltage between the ungrounded 277V conductor and the ungrounded 120V conductor is 380V. Does...

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404.8 (b)

What is the intention of 404.8 (b)? Does this literally mean I can't have two switches from different circuits in the same box?

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[don_resqcapt19]

I believe there are at least 7 possible voltages between the conductors of a 208Y/120 volt system and those of a 480Y/277 volt system, with 3 of those voltages being less than 300 volts.
Most AHJs will require the barriers even where there are conductors from both systems in the box.