Which cable for tri light?

[PhillM]

Mast down so re-wiring the lights. What is the best cable to use for a tri-25 W 12 v light? I have read that I need to take into account voltage drop etc. I want to use best quality as I dont plan to take the mast down for another 5 - 7 years.

I also need to run a cable for a steaming / deck light combo. I am assuming 3 core for this but again need to take into account voltage drop.

Boat is 25' and mast 8M high so assuming that total run from mast head to switches is about 15m (30m return).

What does the forum think?

 

[prv]

I think it's worth fitting LEDs. This in turn makes the wiring easier, as you don't need to pump 25 watts up there. Also much easier on the batteries, and less likely to fail in a number of ways.

I've just bought 100m of this cable for rewiring on the new boat, including the mast: http://www.iem-services.co.uk/showdetails.asp?id=1324 . If you insist on heating up old-fashioned coils of wire in your lamps, you may need something chunkier (I haven't done the maths).

Pete

 

[Ru88ell]

I think it's worth fitting LEDs. This in turn makes the wiring easier, as you don't need to pump 25 watts up there. Also much easier on the batteries, and less likely to fail in a number of ways.

+1

 

[VicS]

Mast down so re-wiring the lights. What is the best cable to use for a tri-25 W 12 v light? I have read that I need to take into account voltage drop etc. I want to use best quality as I dont plan to take the mast down for another 5 - 7 years.

I also need to run a cable for a steaming / deck light combo. I am assuming 3 core for this but again need to take into account voltage drop.

Boat is 25' and mast 8M high so assuming that total run from mast head to switches is about 15m (30m return).

What does the forum think?

25 watts is approx 2 amps at 12 volts

Taking 3% as the max acceptable volts drop, 3% of 12 volts = 0.36 volts.

The resistance which will cause this at 2 amps is 0.36/2 = 0.18 ohms

So if your 30 m of cable has a resistance of 0.18 ohms, 1000 m would have a resistance of 0.18 x 1000/30 = 6 ohms

If you look at THIS TABLE You will see that cable which has this resistance per 1000m would be between AWG 12 and AWG 13
or about 3 mm².

So the minimum cable size for no more a 3% volts drop is 3 mm²


Thats pretty heavy! You could reduce it to 2 mm² if you accept a 5% volts drop

You can virtually over come the problem by using an LED light. Not only will the current be much less but the LED lights are less voltage dependent

 

[Allan]

Adding to the other comments about LEDs at the top of the mast. The Nasa tricolour/anchor light only requires two wires.
Allan

 

[PetiteFleur]

Good advice previously on cable size but don't forget to get Tinned Copper cable as it won't corrode. I went through this excercise a couple of years ago, used tinned copper cable, bought off the internet, but from memory could only get 1.5mm² cable which seems to OK although I should have got a larger size if available.
I used www.kojaycat.com but their website appears to down at the moment

 

[VicS]

Good advice previously on cable size but don't forget to get Tinned Copper cable as it won't corrode. I went through this excercise a couple of years ago, used tinned copper cable, bought off the internet, but from memory could only get 1.5mm² cable which seems to OK although I should have got a larger size if available.
I used www.kojaycat.com but their website appears to down at the moment

Furneaux Riddall have 2 and 3 core tinned cable in 1.5mm² and 2.5mm²

Merlin Powerstore have tinned 2 core in 10, 12, 14 and 16 AWG and 3 core in 12 and 14 AWG

 

[prv]

Furneaux Riddall have 2 and 3 core tinned cable in 1.5mm² and 2.5mm²

Merlin Powerstore have tinned 2 core in 10, 12, 14 and 16 AWG and 3 core in 12 and 14 AWG

The cable I linked to is tinned. I'll admit I didn't bother checking this time around, but it will have been the best price readily available two years ago when I rewired Kindred Spirit.

Pete

 

[PhillM]

Thanks guys, LED was on my to-do list but has had to drop off due to cost overuns in other areas. I shall return to that later.

I have gone for tinned 2.5mm two core for the tri and 3 x core single for the steaming / deck combo.

As I don't plan long multi-night trips, I think this will be ok for next season.

I think that I have enough juice in my 110 leisure to run the tri for around 3 nights or the low levels for one night.

(110 / 40% = 44 amps available. 25w / 12v = 2.083amp so 44/2.083 = 21hours)

The only other draw on the battery is VHF / GPS / LOG and Depth and I dont think they draw much.

Does that sound about right?

 

[davei]

Hi

Thanks guys, LED was on my to-do list but has had to drop off due to cost overuns in other areas. I shall return to that later.

I have gone for tinned 2.5mm two core for the tri and 3 x core single for the steaming / deck combo.

As I don't plan long multi-night trips, I think this will be ok for next season.

I think that I have enough juice in my 110 leisure to run the tri for around 3 nights or the low levels for one night.

(110 / 40% = 44 amps available. 25w / 12v = 2.083amp so 44/2.083 = 21hours)

The only other draw on the battery is VHF / GPS / LOG and Depth and I dont think they draw much.

Does that sound about right?

For what its worth if things are that tight I would be putting a meter in all the other stuff to see what they really do draw.
Good luck

 

[Jaguar 25]

NAS tricolour/anchor light - 3 wires not 2

Adding to the other comments about LEDs at the top of the mast. The Nasa tricolour/anchor light only requires two wires.
Allan

I have just rewired my NASA tricolour / anchor light. There is a positive feed to each light i.e. two wires individually switched plus one common return. So, 3 in all. I used 1.5mm2 tinned wire, which seems fine on my Jaguar 25.

 

[davei]

I have just rewired my NASA tricolour / anchor light. There is a positive feed to each light i.e. two wires individually switched plus one common return. So, 3 in all. I used 1.5mm2 tinned wire, which seems fine on my Jaguar 25.

The new combined NASA tri colour / anchor light on needs 2 wires
It has a switch that simply reverses the polarity

John

 

[VicS]

I have just rewired my NASA tricolour / anchor light. There is a positive feed to each light i.e. two wires individually switched plus one common return. So, 3 in all. I used 1.5mm2 tinned wire, which seems fine on my Jaguar 25.

The Nasa Supernova Combi Tri and Anchor L.E.D mastlight works using only two wires

A simple two wire connection powers the Combi light. Connecting the red wire to positive and the black wire to negative will illuminate the tricolour light. Reversing the connections will illuminate the anchor light.
A rotary switch is supplied with the Combi light to facilitate the supply reversal​

Much lighter cable than 1.5mm² can be used because the lights only draw 0.20 amp and will operate with a supply voltage as low as 10 volts.
The limiting factor for cable size will be physical robustness rather than volts drop

 

[Jaguar 25]

NASA tricolour - number of wires!

Obviously there must be a later (cleverer) version to mine but my combined tricolour anchor light does have three wires.

 

[lustyd]

Are the LED lights officially legal now? The LED guy I spoke to at the boat show was saying there was still a problem with approval of the colours and brightness and I seem to remember one of the mags saying the same within the last year. This is the reason I've held off so I may swap if things have changed.

 

[VicS]

Obviously there must be a later (cleverer) version to mine but my combined tricolour anchor light does have three wires.

There is and its the only only one for which I can now find any info. There must have been very few made like yours.
People were making combined lanterns themselves from the separate tri and anchor lights then the two wire Combi seemed to appear to satisfy the need for a combined unit.