Marine wiring

[Oceanic Dave]

Looking at rewiring some lights on the rocket launcher. I only have 20mm split loom tube to fit:
am/fm radio cable
vhf cable
anchor light
deck lights
front spot light

Now it can fit but will be tight. Since I am upgrading lights to LED i can remove the older thicker wiring and replace it with newer ones.

My question is, is it really necessary to buy wiring with an outer sheath?

The smallest wire diameter i can find is 2mm. They are around 15amp I think. I dont need that much for LED. What is the most common size down? I cant seem to find 1.5mm.

Thanks.

[Rip it up]

Save your space by linking all the negatives as soon as possible. Only run one negative down the tube.

And as long as you can protect against chaff and also run the right amperage wiring to avoid heating the copper you should be able to run single sheath.


Damo's dodgy boat building repair centre.

[stevebris]

Also make sure the wire is pre tinned, no corrosion. Size of cable is irrelevant, it is the amp rating you need to consider. Damo is on the money, run a single neg to all.

[Noelm]

Makes no difference if you run only one negative, or one positive, the same current passes through either "leg" how about a thicker twin, double insulated and tinned, then take the feed and returns off that?

[scottar]

Different opinion on the negative. Creates a common failure point for all adjoined services that will be in a split loom out in an area that will see water. Single sheathed wire is not an issue provide sufficient chafe protection is provided where necessary. My last tinnies lights were wired with single sheath, non tinned cable and were still fully functional 15 years after having it done due to the necessary steps being taken to protect the wire from water and abrasion. Tinned wire is a good idea as it will slow corrosion should water come into contact with the cable. The other option if you don't have sufficient room is to add a loom on the other side of your launcher frame as well. Run the low current devices either across under the dash and through the bulkhead or go the whole way around. The size of the cable serves a couple of purposes IMO - primarily to carry the current, but the secondary issue a lot of people don't consider is the physical strength in an environment that is somewhat hostile with both corrosion concerns and high levels of mechanical vibration. Personally for 12 volt, I never use anything under 3mm automotive twin and prefer 4.

[Fed]

Should be easy with six single insulated cables plus two aerial leads, what amps do you need for the lights?

[Oceanic Dave]

I don't think the lights draw more than 2 amps!

I will be giving it a go soon, maybe I will jus stick to 2mm then single sheath.

[Moffy]

Not sure if this suits - but used this for my under gunnel led install recently.

https://www.whitworths.com.au/main_itemdetail.asp?cat=123&item=33156&intAbsolutePage=1

[Fed]

1.0 mm² is good for about 10 Amps.

[scottar]

Sorry should have also made reference that "mm" when referring to automotive wiring is actually a size - not a measurement. "3mm Automotive twin" has two conductors with a cross sectional area of 1.13 square millimetres and is generically regarded as "10 Amp" cable. This is dependant on the length of your run. There is some good info on Redarc's site on this
http://www.redarc.com.au/images/uploads/files/wire_gauge_worksheet.pdf

[rayken1938]

If you go the single earth wire ensure that it can carry the sum of all the devices turned on together.
Cheers
Ray

[kizza1]

what about running a splitter on the radios, so that you only need to run the 1 aerial. then 7 core trailer wire. make sure you use waterproof joiners and you wont have an issue with corrosion. ideally use tinned wire if it will fit. whats the specs on the spot light/s? as this will draw the most power