Wire type questions

[Rainh2o2]

I am about to start rewiring my small boat. Going to totally replace all wires and install new circuit breakers and switches. The stuff that's in there now seems to be all corroded up and POs have done a hack job over the last 38 yrs with splices onto splices, combination of butt crimps and wire nutts and inline fuses. Its a mess.

Anyhow, Im curious about types of wire. I know to go with stranded type but what about the stranded zip wire? Looks sort of like lamp cord but is red and black. It claims to be true 14 guage. I do need to find out how many strands to figure true current capacity though. I was thinking it would be simpler and cleaner and easier to run. Or should I just run 2 separate wires to each circuit (same guage of course)? The only thing i can think of is heat, 2 separate wires could probably handle the heat of the circuit better.

Am I missing something?

This is all for the 12v side of things. The AC part is another story.

Edit: all lighting has been changed to or will be changed to LED by the way.

[Reefmagnet]

Using twin core is way less messy then individual wires and wont overheat anymore then a bunch of single cored wires tied together.

As for current capacity (and apologies for going metric) a rule of thumb is that each 1 mm2 of wire cross section will be good for 10 amps for up to 10 metres.

[Jman]

So long as it is tinned copper, any other material should be avoided. Technically DC wire on a boat should be yellow/red, not black/red. 14ga would be way overkill for led lights.


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[travellerw]

Be prepared for many views on tinned/non tinned.

I have tinned wire on my boat and it still corrodes if not terminated correctly (at least in the tropics). No matter what you go with, ensure you terminate it correctly (adhesive lined heat shrink).

If you are running anything through the bilge, I suggest true marine grade wire with double insulation. Believe it or not, but water will penetrate standard PVC wire if its in the bilge.

[Rainh2o2]

Originally Posted by travellerw

Be prepared for many views on tinned/non tinned.

I have tinned wire on my boat and it still corrodes if not terminated correctly (at least in the tropics). No matter what you go with, ensure you terminate it correctly (adhesive lined heat shrink).

If you are running anything through the bilge, I suggest true marine grade wire with double insulation. Believe it or not, but water will penetrate standard PVC wire if its in the bilge.

Yes I have read the tinned/not tinned views. The original wiring is not tinned and it's corroded...however like I said is over 30 yrs old. Meh. For termination I did plan on adhesive heatshrink or terminals.

The only thing I will have running through the bilge is the bilge wiring but my bilge is bone dry all the time since I resealed my windows and deck hardware but I'll check into buying some wiring for the bildge pump...that's one thing you do want to work when you need it.

I chose 14 guage due to installing a few more 12 volt outlets and I can get 100 foot of it pretty reasonable so I was just going to use 14 guage for eveything except maybe the bilge pump. Thinking some 12 guage for that.

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[alx]

I'm in the middle of a full rewire of my J/30 currently.

Previously I've found duplex wire to be unwieldy. Sometimes it makes sense to run positive wire from panel to load and then return directly to the battery. Using primary wire saves on space and has less voltage drop because circuits tend to be shorter.

I've been using tinned copper from bestboatwire.com, with heat shrunk terminals and heat shrunk labels applied using my Rhino label maker.

I should do a thread on my rewire, actually.

[rwidman]

Originally Posted by Rainh2o2

I am about to start rewiring my small boat. Going to totally replace all wires and install new circuit breakers and switches. The stuff that's in there now seems to be all corroded up and POs have done a hack job over the last 38 yrs with splices onto splices, combination of butt crimps and wire nutts and inline fuses. Its a mess.

Anyhow, Im curious about types of wire. I know to go with stranded type but what about the stranded zip wire? Looks sort of like lamp cord but is red and black. It claims to be true 14 guage. I do need to find out how many strands to figure true current capacity though. I was thinking it would be simpler and cleaner and easier to run. Or should I just run 2 separate wires to each circuit (same guage of course)? The only thing i can think of is heat, 2 separate wires could probably handle the heat of the circuit better.

Am I missing something?

This is all for the 12v side of things. The AC part is another story.

Edit: all lighting has been changed to or will be changed to LED by the way.

I don't know about that "zip wire" I've seen a black and a red wire enclosed in a sheath and listed as "boat cable".

The smartest thing you can do is to make sure any wire you use is listed as "boat cable" or "boat wire". It will have lots of fine tinned strands.

As for current carrying capacity, don't try to measure it and calculate the capacity, the size will be printed on the insulation. Look it up on the Internet or in the West Marine catalog.

This is a great place to buy marine wire and cable as well as terminals:
Marine Wiring, Boat Cable and Electrical Genuinedealz.com

[exMaggieDrum]

IMO don't use zip wire for any circuit on the boat. Perhaps for speakers if you don't mind replacing it often. Duplex wire actually can be simpler and it is more durable but it does add bulk and is more expensive. I do recommend you do run positive and negative wires together for each circuit, i.e. not run the positive one way and the negative the other. It will save enormous amounts of time if you have to trouble shoot a problem, either during the installation or after. Use terminal buses for the negative wires at the panel or elsewhere and run a bigger wire back to your main negative bus. Be tidy and don't cut corners. IMO use only marine grade tinned wire for everything.

Lay wires along surface with lots of wire ties and secure points to the boat. I love wire ties and wire tie mounts. I hate the "p" type clamps that surround bundles or single wires. You'll find out why if you use them. They look really pretty sometimes and may seem simpler to install but...... I love square drive screws too - easier to hold them on your bit when you have to put one inside something you can't get your hand/fingers in to hold the screw. A real time and screw saver.

[Zil]

I don't know why there is a controversy about tinned or plain wire. On a boat use marine wire. Marine wire is fine stranded tinned copper wire with the proper insulating covering. genuinedealz is a good supplier.

[travellerw]

Originally Posted by Zil

I don't know why there is a controversy about tinned or plain wire. On a boat use marine wire. Marine wire is fine stranded tinned copper wire with the proper insulating covering. genuinedealz is a good supplier.

3 reasons.. 1 as I understand it, in Europe tinned is not a requirement.

2.. Us that have had tinned wire for a longer period on our boats don't see any benefit over standard wire. My boat was built with tinned silicone insulated wire, but the original owner added a bunch of things with standard wire. Some of that standard wire is holding up better than the tinned stuff. Its all down to termination and protection.

3 Extra cost. You can get fine stranded plain copper wire for 1/2 of tinned wire.

I'm not advocating either way, I'm just posting the facts of why its a controversy.

[Rainh2o2]

I noticed that the original wire in my boat is not tinned. It is corroded in lots of spots but it is also 38 yrs old. Meh.

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[thinwater]

Originally Posted by Zil

I don't know why there is a controversy about tinned or plain wire. On a boat use marine wire. Marine wire is fine stranded tinned copper wire with the proper insulating covering. genuinedealz is a good supplier.

• Because the US Coast Guard approves THHN wire and SAE wire.
• Because I did a 2-year salt spray chamber test of THHN wire for a sailing mag and could not induce a single failure over >100 crimps. Some of the terminal block fell apart.
• Because I've got a 20-year-old boat and all of the wire in the cabin is still shiny.

There is little question that tinned wire is easier to repair later if run in a damp area. But unless you have water up in your cabin and panel (in which case the boat is either a flooded loss or a mildew factory), non-tinned wire is fine. Damp areas (exterior lights, bilge) should be tinned, but it is not required.

[exMaggieDrum]

All I can say is that in my career I replaced many miles of untinned wire and only some tinned wire and that was usually because it was subject to salt water corrosion which corrodes all types of wire. Of course I also replaced miles of poorly installed wire with or without any corrosion, i.e. corrosion was not the reason it was replaced.

But the untinned can work especially if good practice is followed and the wire and connections are inspected on a regular basis. I say this conservatively as that is what I do with all wire on my boat.

If you do you use non-marine wire you should at least get wire that meets other important standards such as resistance to solvents, oils, and diesel. And heat if in hot spaces like the engine room. The reason to install marine grade wire is not just because it might be tinned. There is wire that is untinned that is fine, but not all of it. There have been several threads about this for battery cables in the last year. All with equal controversies.

I find it much easier to suggest marine wire to amateurs who do not know the difference and often make very poor choices. I have seen all kinds of wire on boats. Those of you who are smart enough to make good choices - fair winds and calm seas. The rest of you would do well to pay a little more for marine wire. To each his own.
Joe

[alx]

Originally Posted by exMaggieDrum

I do recommend you do run positive and negative wires together for each circuit, i.e. not run the positive one way and the negative the other. It will save enormous amounts of time if you have to trouble shoot a problem, either during the installation or after.

Can you share a little bit more about the logic of this and the types of problems that it helps troubleshoot?

[travellerw]

Originally Posted by alx

Can you share a little bit more about the logic of this and the types of problems that it helps troubleshoot?

Having a "Home Run" for both positive and negative wires makes it much easier to troubleshoot wiring issues. Since %99 of issues are terminations, this will give you only 4 terminations to check (2 at the device, and 2 at the panel). Since the wires are bonded together it makes tracing the negative and positive terminations easier as you only have to trace where the wires split and go to their respective terminations at the panel (positive to a breaker, negative to a distribution block).