Re-wiring: Electrical conduit

[Iain_H]

Just been adding a circuit breaker panel to my small 27' yacht. Just discovered some burn marks on two of my cables so they are getting replaced. I'm now replacing all the old household (thin cable) with belts and braces AWG 14 tinned (insulated two core) for everything as I bought a roll of the stuff.

This has meant that I am now required to drill larger holes to accomodate the dual core cable. I'm not too keen in having extra opportunities for water to seep into other parts of my boat and I'm afraid that above water-line connections would get messy. I am therefore now considering conduit for everything. However I'm not sure how to tackle it.

I'm thinking of going for the smallest conduit I can. This would be one with an outside diameter of 11.5mm and an inside diameter of 8.4mm. I would then be considering taking the insulation off of my two core cable, leaving just the two wires to thread through the conduit. At most I would have two sets of red and black AWG 14 wires going through the conduit, together with a leading wire for any future additions. Once the conduit is in place I am considering sealing it to the wood which I am drilling through to accomodate. i.e. sealing the outside rim of the conduit to the wood to prevent water seepage.

Questions:

1. Is my conduit wide enough?

2. Do you believe its okay to take my two wires out of their insulation to place this into the conduit?

3. Although there are T-blocks etc, what is your advice for sealing the wires when they leave the conduit to attach to (e.g.) autohelm or nav lights?

4. What would I use to seal conduit to wood for waterprrof connections? Glass fibre bubbles?

5. Any other tips/suggestions?

Many thanks in advance. Oh for the day when I can surf the web bobbing on the sea paying back all your good advice by responding to queries from others.

 

[misterg]

The way I overcame this when I re-wired our 22' boat was to mount a (large-ish)waterproof junction box on the main bulkhead under the cockpit, bedded on sealant. Holes for wiring were drilled through the bulkhead into the box and the wiring was threaded through as normal. Cables exiting the box to individual items went through waterproof cable glands fitted to 'knock-outs' in the waterproof box.

This worked well, and (in theory, at least) provides a watertight barrier. Conduit is handy for keeping things neat, but use the biggest you can - again, I used 1.25" waste pipe for the major run from the fuseboard. The 20 or 30mm stuff (rigid and flexible) that B&Q carry is quite handy. What you're proposing sounds very small.

0.02p

Andy

 

[simonfraser]

you're bound to want to add to it later, so make the conduit bigger as prev post sugested.
my boat uses plasitc drain pipe. the electrical connections are above the water line.

none of the pipe connections are water proof. it's been like that for the last 8 years, seems to work well.

 

[halcyon]

Also bear in mind cables in conduits need to be a different rating, temp build up / higher rated insulation.
This also applies to harnesses, so check rating and loadings to be safe.
Brian

 

[jhughes]

You might getaway with using small bore conduit for straight runs but you will struggle pulling the wires through any bends.