AC/DC Segregation

You will need to check you local electrical regulations for these answers as it depends on the application. My understanding was it's ok (as long as you follow proper wiring segregation and creepage and clearance requirements), but it may be different in US (especially if the circuit breaker is part of the main switchboard circuit and has special requirements).

If you supply more information on your application someone here may be able to point you to the applicable regulation and chapter.

You can have the discreet devices wired in the same box but the wiring should be kept seperate. But if you have an AC circuit breaker feeding a DC controller in the same box that's OK.

If you are designing a AC to DC power supply that is on one PCB then there are manditory segregation protocols that have to be followed to meet UL / CSA requirements. But I don't think that's where you're going.

My appologies for not being clearer on my application.

The only way i could describe this application would be for the like of a control system for a diesel generator. Where we use the circuit breaker as more of an on/off switch rather than circuit protection.

Specifically, what i was wondering is that if we have the generator control section and wiring of the control section in the same box as the circuit breaker (switch) and cabling, with the intent that the control section would be attached to the front of the box with the breaker attached to the back of the box with the cabling leaving the top back of the box.

I have seen it done on other generator set control panels but none of them have been NEC, NFPA or UL Cert.

You are right, my Kawasaki generator has the AC control and engine / excitation control all in the same enclosure. I don't know if it is UL certified. I'll have to check.

You should be able to download the UL standard from their site.

Caveats: First, double check with the NEC. Second, check with your local building codes to see if they have more restrictive rules as stated previously.

My understanding is that low voltage control circuits can share the same space as long as all the wiring in that space has a minimum working voltage of the highest voltage present. Seems to me that DC circuits (Of whatever voltage) would apply here as well.

Cheers!!

AC and DC can be in the same cabinet without shielding or barriers at low voltages, but DC and AC wiring should not be put in the same conduits from such enclosures, not that you asked that question . . .