what amp rated cable should i use for spotlights

Hugh Jardon · 17 January 2006, 11:37

a question for you leckies out there, what amp cable should i use to run a pair of spotlights that are 55w or 100w at a distance of 6-7m from the switch and relay assembly. I cant seem to find any info easily that tells me this. gauge of wire or amp rating would be fine, i would probably just go with twin 55w lamps but would be interested in cable sizing for 2x100w lamps

Mollers · 17 January 2006, 11:51

Stroll on!! Talk about boat building by numbers! Didn't you get any instructions with it?

Hugh Jardon · 17 January 2006, 12:02

i am prewiring the boat for additional items i will add in the near future or items a future owne could add, so that it is just a case of connect and go so to speak, flood wiring it could be referred to as i suppose!!

Quote:

Originally Posted by Mollulnan

Stroll on!! Talk about boat building by numbers! Didn't you get any instructions with it?

Mark Halliday · 17 January 2006, 13:33

28/0.03 2mm² is the smallest you want.

Standard cable rated @ 17.5A
Thinwall cable rated @ 25A

Why?

P=iV

i = 200W / 12v = 16.666.....A

[Edit]
Have a look at www.vehicle-wiring-products.co.uk/VWPweb2000/homepage/home.html for some useful info.

Hugh Jardon · 17 January 2006, 13:51

thanks for the link to the site, very useful, it was the voltage drop i was interested in over a 7m length but i have been advised it should be minimal so will order up some cables today

thanks

Quote:

Originally Posted by Mark Halliday

28/0.03 2mm² is the smallest you want.

Standard cable rated @ 17.5A
Thinwall cable rated @ 25A

Why?

P=iV

i = 200W / 12v = 16.666.....A

[Edit]
Have a look at www.vehicle-wiring-products.co.uk/VWPweb2000/homepage/home.html for some useful info.

Mark Halliday · 17 January 2006, 15:02

There wont be much voltage drop over that length.

Again by the above formula, yer 200W will be little less, thats all.
You will still have enough to dazzle your hardboating chum.

Scary Des · 17 January 2006, 15:07

I’d be inclined to use marine grade wire

it does help to stop the rot

having said that tis more expensive so it might be worth doing a cost benefit analysis

Des

Nauti Buoy · 17 January 2006, 15:11

Quote:

Originally Posted by Mark Halliday

You will still have enough to dazzle your hardboating chum.

Oooohh B**ch

Hugh Jardon · 17 January 2006, 15:16

i am fitting a rear view mirror especially so i can keep and eye on him....haha

Quote:

Originally Posted by Mark Halliday

You will still have enough to dazzle your hardboating chum.

Mark Halliday · 17 January 2006, 15:25

Quote:

Originally Posted by Scary Des

I’d be inclined to use marine grade wire it does help to stop the rot having said that tis more expensive so it might be worth doing a cost benefit analysis Des

A dab of "Liquid Tape" can stop the nasty salty air getting down inside joint and the insulation.

Quote:

Originally Posted by Nauti Buoy

Oooohh B**ch

Quote:

Originally Posted by Hugh Jardon

i am fitting a rear view mirror especially so i can keep and eye on him....haha

Hugh Jardon · 17 January 2006, 15:34

Quote:

Originally Posted by Scary Des

I’d be inclined to use marine grade wire

it does help to stop the rot

having said that tis more expensive so it might be worth doing a cost benefit analysis

Des

i did some cost benefit analysis on marine grade wire and decided to tinn the ends and crip and solder as well so the ends are sealed from our friend mr salty

a much cheaper option and does the job nicely

Mark Halliday · 17 January 2006, 15:44

Tinning will only protect a short length of conductor inside the insulation.

Liquid Tape will seal the end of the insulation to stop moisture (with added salt) tracking down the inside and turning it all green and horrible. I only treated some of my wiring this way, and the bits that were not sealed have gone yukky in under a year.

Now go and rip out all that lovely wiring and do it properly.

Nauti Buoy · 17 January 2006, 15:49

Quote:

Originally Posted by Mark Halliday

Now go and rip out all that lovely wiring and do it properly.

yeah!! and get rid of that rear view mirror whilst you're at it too.... unless you want to use it to put ya lippy on

jwalker · 17 January 2006, 17:13

I would use the theory and then triple it. You'll likely then only need 55w bulbs.

Rogue Wave · 17 January 2006, 19:24

Quote:

Originally Posted by Hugh Jardon

i did some cost benefit analysis on marine grade wire and decided to tinn the ends and crip and solder as well so the ends are sealed from our friend mr salty

a much cheaper option and does the job nicely

The sir you really don't know much!

The problem with an opiniated person giving everyone the benefit of his lack of experience is that some novices might take it!

I find it quite irksome that you dish out iffy advice whilst masquerading as a boat builder......what kind of service do you think that does the Forum.......Your'e not from Swansea are you?

Hugh Jardon · 17 January 2006, 21:06

Mr Wave,

occupation is listed as boatbuilder in jest only as i seem to be spending my evenings out there fiddling around and taking pleasure in building MY rib, MY rib, repeat My rib, not anyone elses!!!! so to save confusing you i have changed my occupation ....just for you!

Do i have an opinion, i sure do, do i push it on other people, hopefully not, but more than happy to speak my mind.

On this thread I asked advice on the grade or rating of wire to use for spotlights over a 6-7m run considering the drop that may occur, hardly think i was pushing out advice do you?

SOOOOOOOO

thanks to all those below that gave some good info and advice and those that pm'd with some good info on voltage drop..

and

Rogue Wave, thanks for your valuable contribution, much appreciated, or as my Mrs just said.....what an asshole!!

Quote:

Originally Posted by Rogue Wave

The sir you really don't know much!

The problem with an opiniated person giving everyone the benefit of his lack of experience is that some novices might take it!

I find it quite irksome that you dish out iffy advice whilst masquerading as a boat builder......what kind of service do you think that does the Forum.......Your'e not from Swansea are you?

Hugh Jardon · 17 January 2006, 21:12

this was sent via pm to me and is a very useful chart, just wanted to share it for others to reference

Rogue Wave · 17 January 2006, 23:56

Quote:

Originally Posted by Hugh Jardon

Mr Wave,

occupation is listed as boatbuilder in jest only as i seem to be spending my evenings out there fiddling around and taking pleasure in building MY rib, MY rib, repeat My rib, not anyone elses!!!! so to save confusing you i have changed my occupation ....just for you!

Thank you. I guess I didn't miss you much eh

Hugh Jardon · 18 January 2006, 08:28

to any newbies out there here is some information that may be of use

Pre-tinned wire is the best by far but it seems few boat builders and assemblers use it. Many ribs out there are built with standard wiring it would seem. Pre-tinned wire is quite/very expensive, however there are some steps you can take to extend the life of standard wiring, if you have standard wiring keep an eye on it and be prepared to change out cables if problems occur.

some boat builders only use a2 fasters, a4 are the best, but Titanium is better still!!, some dont even use stainless!

some boat builders dont use lock nuts and just use normal nuts so everything keeps coming apart which can be a real danger at sea at worse and a real pain in the arse at best.

take advice from more than one source and form your own opinion

a lot of things in life are a compromise or just personal choice

Jerry Davis · 18 January 2006, 19:42

to any newbies out there If it's worth doing it's worth doing right!