Running 110V next to 12V while at shore

[zinahewitt]

Hi All,

I have a Dufour 34 1975.
It never had shore power. I added a box with 30 amps, 3 switches with 2 used for outlets which I custom built somehow. {thanks youtube}

so I was planning to run an electrical wire , 110V , which will go into an outlet on the box, the wire will run in that brown piece
which runs along the boat, let us call it the Electric Conduit. This will go all the way to the V berth where I can put a generic socket.

That brown Electric Conduit thing runs from the back to the front of the boat and has the 12V wiring for lights and similar.

I was told and read one should not run 110V wire near 12V wire.
I still want to do this, so my questions are.

1. Should I do this ?
2. Do I need to use a conduit inside the brown one and if so which conduit type would you recommend ?


Thank you
Electricity and plumbing are not my strong suit.

 

[dlochner]

I was told and read one should not run 110V wire near 12V wire.

The concern is inducing an AC current in the DC wiring. This can only happen when there is AC flowing in the AC wire. So long as the wires are straight, not coiled the induced AC current is pretty small. This is "wireless charging" the way many small electrical devices are charged, things like cellphones, Apple Watches, and electric toothbrushes.

Whether the induced current on your boat is an issue or not, really depends on a lot of factors. On the DC side, if the circuit is used for sensitive electronics or LED lights, it might be an issue if the current is large enough. If the wire is solely used for incandescent lighting, probably not, but who uses incandescent lights on a boat anymore? Likewise, if the AC current is high, say running an electric heater or hair dryer, the induced current will be higher. But, if there is no DC device turned on, there will not be an issue.

Thus, while running AC next to DC might not be a problem, all the variables make the safer answer is to keep them separate.

 

[Davidasailor26]

ABYC doesn’t explicitly say that you can’t run the conductors together, only that if you do the AC conductors “shall be sheathed, bundled, or otherwise kept separate from DC conductors.” Generally if you’re using AC wire in a 3 conductor package it’ll be sheathed itself, which should meet the requirement.

Having said that, there are many other considerations that come with AC wiring which, if not done right, can affect not only your safety but also that of neighboring boats. If you don’t feel comfortable with the requirements and best practices it may be best to do further research or bring in a certified marine electrician.

 

[sailme88]

If you think about it, installing a Xantrex type battery conditioner requires that the AC & DC be in close proximity, Same holds true with an inverter. Just don't make a coil ( magnetic) zone that the other wires pass thru.

 

[jssailem]

I am unaware of any regulations that apply to this particular case.

I would be sure that the insulation on all the wires (both AC and DC) meets the requirement of the highest voltage present in the common conduit. Be sure there is adequate space throughout the entire run for all the wires. Cramming the wires together could create an opportunity for chafe issues.

 

[Davidasailor26]

Cramming the wires together could create an opportunity for chafe issues.

Bundling more wires together also has implications for their maximum ampacity, since they can’t dissipate heat as well as single conductors in air. ABYC lists this out in their wire gauge tables.