Svenska IF-båtförbundets forum • Cable type
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Cable type

Postat: sön 18 jan 2015 22:16
av Captain_frog
Hello Sailors

I would like to install an Anchor light (LED 1,5 watts) on the mast top of my IF. What kind of cable should I use in the mast to be sure it does not produce short cuts and how should I proceed to be sure it does not get entangled with the main halyard.

Any suggestion is welcome

Re: Cable type

Postat: sön 18 jan 2015 23:49
av maja
As the power is quite low (only 1.5 W), the voltage drop through any cable will also be low. So I imagine that the essential voltage drop will occur in the cable connections. So, as LEDs are sensitive from voltage drop, you should pay extra attention of having all connections well done and of high quality.

Re: Cable type

Postat: mån 19 jan 2015 20:15
av johan swe-1870
Good question!

The power is 1.5 W. I = P/U = 1.5/12 = 0.125 A.

I can't find data for such a low current. However I found this diagram showing Maximum distance one-way of various gauge two conductor copper wire from power source to load for 2% voltage drop in a 12 volt system:


AWG 4 wire has 15 A at distance 40 ft, AWG 12 wire has 1.5 A at distance 40 ft. It would seem plausible that for 0.15 A and 40 ft an AWG 20 is enough. AWG 20 wire has a cross section area of 0.5 mm2.

It would be quite interesting to read more on how to choose copper wire in a 12V system at low current. I think the new LED light bulbs' requirements are not fully documented.

Please research and add to this thread!

Re: Cable type

Postat: mån 19 jan 2015 20:27
av johan swe-1870
Here's another interesting page on Cable Sizing & Selection

Re: Cable type

Postat: ons 10 jun 2015 14:38
av kubal
When dealing with 0.125 A, do not care about wire cross-section. Mechanical properties are more important. Select the electric cable like a rope: take it into hands and try to judge whether it can withstand the pulling and the wearing by friction with halyards. If it can, than it will have sufficiently thick wires :-). Try to select cable with tinned wires. Do not use silicon rubber or other soft insulation. I was lucky to find tinned cable with some quite hard plastic insulation in one better electric shop.

If you do not find some way to fix the cable inside the mast and let it hanging from the top, it will produce noise after every slightest movement of the boat, even in a harbour. You and your neighbours might become crazy because of the permanent noise! I have it done this way, so I get used to it. It has never been entangled with halyards. Be sure that the electric cables and halyards are not turned around each other when puling them through the mast, that the electric cable is not loose and that the lower end can not be pulled inside the mast. David