120VAC and 125Vdc Wires in Wireway

[nightfox1925]

I have a little circuit which do some VFD pre-charging. The coils are operated at 120VAC and one of the out contacts is used to close a circuit breaker rated for 125Vdc (Potter Brumfield KUEP-3A15-120).

Due to limited space for putting a separate wireway, the wires are inevitably installed in the same wireway. Both are digital signals. If the wire insulation is 600VAC, I am thinking that it will be fine as long as I properly mark which is AC and DC.

Any comments?

 

[EEJaime]

As long as the insulation is the same rating, there are no code implications.

 

[nightfox1925]

Thanks EEjaime. My next question is:

There is an unexpected requirement at site to wire in a 52b to dropout a 120VAC interposing relay coil after a successful breaker operation. Unfortunately, we ran out of spare cores on the 120VAC 4 core control cable from the switchgear to the VFD. The Digital Input control cable from the switchgear going to the VFD input card (for breaker status coming from a 52a dry contacts) has 2 cores spare. We are intending to use it for dropping the 120VAC interposing relay coil (via 52b) as mentioned above.

Since the cores are insulated to 600VAC, I believe I can combine the digital status input with the 120VAC control. I assume the digital status input is around 6Vdc powered by the VFD input card.

There is an RC snubber installed at the 120VAC interposing relay coil for arc suppression.

If we properly identify the wire tag of these cores to indicate 120VAC and say VFD input will the installation be technically acceptable?

 

[marks1080]

Are you talking about running AC and DC in the same cable? Not sure what you mean by 'cores'. Is that the same as 'conductor'?

 

[nightfox1925]

Its a 6 core, #14AWG TECK cable. Each conductors (cores) are insulated at 600V. I am using 4 cores as a digital input and the other 2 cores wired to a 52b contact in series to the interposing relay coil (used to drop out the relay coil). A surge suppressor (RC snubber) is installed across the relay coil.

 

[dpc]

It's not a code issue. There could be some induced noise, but if both the ac and dc circuits are dealing with hard-wired electro-mechanical relays and not solid-state I/O, I don't think you'll have any problems.

"Theory is when you know all and nothing works. Practice is when all works and nobody knows why. In this case we have put together theory and practice: nothing works... and nobody knows why! (Albert Einstein)