hiding the wires

[averypb]

I'm rewiring my boat and need some advice. A goodly portion of the wiring will be going thru the engine compartment & a small amount just above the bilge. I want to keep the wiring inside conduit as much as possible. My original plan was to go w/ PVC, but then I read in a couple of sources not to do this. So I investigated flexible conduit but it's TOO expensive. What's the advice/experience/thoughts out there?

Paul

[Mike Vogdes]

Hey Paul

Whats the problem with using pvc? I have allways used it where possible and have never had any problems. Just curious..

[George Roberts]

Remember that the conduit is a wet location and you need to use a wire with a "w" in it. (Most wire THN, THHN and such is also rated as a "w" wire. Romex is not.)

[JeffH]

The trick used at Rockport Marine was to run PVC pipe through the table saw along the centerline of the pipe so a slit was cut the full length. Then standard plumbing fittings, i.e. elbows and angles and so forth, can be used to make the wiring runs. The slit, when installed, was angled as to be out of sight but accessible so that wire could be run through it at a later date should it be necessary. Simple, cheap, effective and it looks good. The only prohibition against plastic that I know of is from the Coast Guard, which doesn't like it used since it could melt in a fire and then drop live wires into the accomodations. As long as metal hangers are used to secure the PVC, I can't think of any reason to not use it. Out of curiosity, why was PVC not reccommended?

Jeff

[ 12-17-2002, 09:27 PM: Message edited by: JeffH ]

[Concordia..41]

Just use marine grade wire and bundle it with spiral wrap if you have several wires in a run and support it every 18”. That is all that is required by the ABYC standards. Anchor marine wire comes in all sizes, single strand, duplex, triplex and fourplex. There are different color codes for AC and DC installations. DC now uses a red and yellow wire, replacing the old red and black so the ground will not get connected to a hot AC black wire by mistake. AC wire is black, green and white. Marine grade wire has a tin coating and more strands as well as better insulation than auto or building wire. It cost more but is well worth it in the long run. Our Home Depot even carries it down here. They also carry a blue flexable conduit that is not expensive.

West Marine catalog has a wire chart with both 10% and 3% voltage drops for 12 volt wiring. ABYC standards are another good source for correct wiring on boats.

Dave

[ 12-17-2002, 11:12 PM: Message edited by: Concordia..41 ]

[ion barnes]

Good ol' West Marine catalog or get your hands on an Anchor catolog. They will show everything you might need to do a good and best yet, a safe job. Check out the automotive supply houses too. Spiral wrap or the split wrap is available along with nylon clips etc. In my line of work, anything related to healthcare, aviation, or marine, the pricetag is doubled or more just because its certified and it rubs the wrong way.

[Bryan Mehus]

Paul,
I see nothing wrong with using pvc pipe as a rigging tube, common sense keeps it away from high temperature sources. Always consider the heat generated in the bundled wires(or in the raceway) and adjust wire size and fusing accordingly. Much of this is outlined in marine electrical suppliers catalogs.
The blue flexible tubing that Concordia mentions is probably NMFT non-metalic flexible tubing. This can be used, again paying attention to the rated temperature and strapping properly. In this case I would probably finish the end of the tubing with the appropriate connector into a piece of aluminum or stainless angle, and have the wires issue from there. Another caveat, don't pull the ty-raps too tight, and cut the tails off with flush cutters(so as not to have that knife edge of nylon waiting to slash your radial artery)

Bryan

[Pekka Huhta]

A marine standard is to use halogen-free cables, which don't emit halogens during a fire. PVC is about the worst you can choose what comes to halogens. Check your regulations, I don't know what rules apply to small wooden boats around there. Any halogens on cables or their covering is prohibited on any larger commercial vessels.

I did my own wiring by salvaging a few coils of halogen-free multi-core cable from a dumpster at work. A length of 7-core cable was all I needed. The cable costs about $5-10 per yard if you buy it by the yard. Compared to normal cables plus spiral wrap or other covering... Not too much.

I have the "main power station" in a locker near the motor. The electricity comes from fuses/switches to a terminal strip and is divided into a 7-core 2,5 mm2 cable and a few 2-cores which go to nearby lights (running lights, compass light etc.)

The 7-core goes to the chart table where most of the electricity is needed (as you probably can count, that isn't much with one 7-core). Over there it's divided to mast lights, instruments and lighting on a smaller terminal strip.

The multicore cable is easy to clip on with screw-on cable holders and cable ties.

If you put on several cables you can have intermediate terminal strips here and there in the boat (ideally with a few unused terminals in them) and if you ever need more electricity you can just put in a small length of cable from the nearest terminal strip instead of running a cable all the way from the main fuse panel.

And remember to keep record where your wires go. A hand drawn connection diagram behind the fuse panel is your best friend when the lights go out.

Pekka

[averypb]

Thanks to all for the input. To answer Mike about why not PVC, J. Payne's Marine Electrical Bible notes not to use it in the engine room. This safety issue alluded to by Pekka and others who replied. The concern is temp rating I suppose. Of course on the other hand if you've got high heat or fire in the engine compartment then there are bigger issues to worry about than PVC melting! I have since found reasonably priced high temp stabilized nylon corrugated loom tubing & fittings that should do the trick.
Paul

[AlexM]

Originally posted by averypb:
Thanks to all for the input. To answer Mike about why not PVC, J. Payne's Marine Electrical Bible notes not to use it in the engine room. This safety issue alluded to by Pekka and others who replied. The concern is temp rating I suppose. Of course on the other hand if you've got high heat or fire in the engine compartment then there are bigger issues to worry about than PVC melting! I have since found reasonably priced high temp stabilized nylon corrugated loom tubing & fittings that should do the trick.
Paul

[AlexM]

Paul:

Where id you find the high temp product?

Alexm

[averypb]

To AlexM,
The heat stabilized nylon conduit is manufactured by Panduit, www.panduit.com. (http://www.panduit.com.) What they don't seem to have however is a good selection of connectors. Only T's, made of polyethelene & not water tight. What I've been trying to find out is if the conduit is compatible size wise w/ connectors from another manufacturer. J&J Electronics, www.jandjelectronics.com (http://www.jandjelectronics.com) has nice fittings & standard PVC corrugated conduit (smaller temp range). I started this whole process with Adaptaflex (UK company). They have everything but it's absurdly expensive. Hope this all helps.
Paul

[ion barnes]

I would look at spiral wrap above the waterline so that the wiring can dry out if it gets splashed(not often I hope), you can trace leads easily, and where you what a branch to lead out, well you just poke it out of the wrap. It does a tidy job.

Into the bilge, well the pvc is OK if the other end comes up out of the bilge water otherwise I would just lay the wiring into the bilge with the understanding that its waterresistant cable such as Anchor. Lets face it, what is attached to your electric bilge pump? A pair of wires from a pump body thats suppose to be buried in the water to be of use, right? dont overburden youself.