Crossing AC and DC wire runs

[TheLake]

Hi all,

I understand that AC wiring and DC wiring shouldn’t be in the Sam conduit. However there doesn’t seem to be any way to avoid them being close together at pinch points and where they need to cross over each other.

In my picture the terminal strips hold the circuits for AC. On the right side are all the circuit wires going up to the breakers. I want to have some of my AC wiring going to the outlets go down the left side. But that is where the main battery cables and starter cables that run to the panel are. Is it ok for them to be beside them for that little bit? About 18”?

There will be places where the wires have to cross or come together at pinch points (eg, the single conduit going to the fly bridge.)

Thoughts?

Chris

 

[NSM]

I just took the USPS marine electrical course and I don't recall any prohibition against running AC and DC together. Maybe I missed that part?

 

[TheLake]

From what I have read is that there is an issue with induced current on the DC circuit.

 

[O C Diver]

Don't think you would have problem. I have both running through the same PVC conduits without issue. Where I draw the line is data cable with AC lines. While I would imagine most data cables (NEMA 2000, CAN bus, etc ) are shielded, putting them in with AC cables seems a bad idea.

Ted

 

[Comodave]

If it would be a big problem then most boats would have it direct from the factory. I wouldn’t worry about it.

 

[CharlieJ]

From ABYC E-11 AC and DC Electrical Systems on Boats:

11.15.4.1.4. When AC and DC conductors are run together, the AC conductors shall be sheathed, bundled, or otherwise kept separate from the DC conductors.

 

[Comodave]

Yes, they should be insulated with a sheath but they can be run along each other.

 

[NSM]

Thanks for the reference Charlie. Can you elaborate on why?

 

[Comodave]

So they don’t chaffe and get A/C on a D/C wire.

 

[CharlieJ]

@NSM #8
This has been a requirement as long as I can remember so the reason is lost in the ether. I suspect that with black insulation being used as both AC line (hot) and DC negative (B-) the idea was to keep them separate so that an unsuspecting person didn't cut into an AC line in the middle of a run assuming he was cutting into DC negative.

 

[NSM]

Thanks Charlie, that makes total sense.