Wiring loom for spots

[Slugsie]

OK, I've bought 6 spots to fit to a light bar. I could make up a loom for it myself, but I spotted this one on ebay.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...034491788&rd=1

I figured it's roughly the same cost as I could buy the bits for, and it's rated to carry enough current (about 27AMPs for 6x 55W lights), so it'd just make life a bit easier for me.

Well, it turned up today, and I'm just not sure it's man enough for the job. Sure, the relay seems OK, and it does have an OK switch that I can mount in the cab, but the rest of the wiring seems far too flimsy.

The main feed from the battery is a single strand of 1.5mm cable rated up to 300/500v. That doesn't seem big enough.

But worse than that is the single strand of cable which can't be an more than 1mm for the earthing.

So, what do the electrical know-it-alls around here reckon? I'm tempted to just strip the relay, fuse, and switch from this kit and make my own loom up as I probably should have done in the first place.

[POPEYE]

Dont know enough about that loom to comment really, looks ok and will be if your useing standard 55watt bulbs in em, when i did mine i used one 30amp relay per pair of spots, (with 55watt bulbs) but used 3mm heavy cable in case i wanted to upgrade the bulbs later, you could just replace the feed to the relay and supply to the spots with a heavyer cable, "safe than sorry" and all that, also used 3mm for earthing, prob is it makes one bl00dy thick loom for six spots,

[Slugsie]

I thought some more about this last night, and I think I'll go with making up my own looms. I've decided that I want to wire them up in individual pairs. If I use a common wire for earth that'll only need 5 wires (the spots hand a halo ring too) so not too bad to route all the cabling.

[TobyJug]

I thought some more about this last night, and I think I'll go with making up my own looms. I've decided that I want to wire them up in individual pairs. If I use a common wire for earth that'll only need 5 wires (the spots hand a halo ring too) so not too bad to route all the cabling.

sounds like a plan mate the 1mm cable will be ok for a bit (about 15 mins hehe) but if u put the lights on for a while I recon it will melt away..
use the proper thick 25amp cable and u cant go wrong..

2x55 watt spots will draw about 7/12 amp I wud imagine so much safer with a bigger cable and per pair.
The 30 amp relay shud be fine but I wud fuse it on 15amp per two..
U gonna run the power straight of the battery?
In that case I wud cut out the relay and just fuse the cable...
lol
If u need some 25 amp thick power cable I am sure I got a few meters laying about somewhere cus I bought half a roll to put my amateur radio's back in..
(hav not put them in yet tho lol)
But not sure will hav a look

[Slugsie]

Cheers Toby.

I've already got some cable around 30amps that I will use for the earth. I'm popping into Maplins sometime soon to get some dash switches and an extra couple of relays so I'll pick up some 10amp cable for the power then.

[Apache]

Dont see how you *can* cut out the relay. How are you gonna switch the lights???

[Slugsie]

Dont see how you *can* cut out the relay. How are you gonna switch the lights???

A high current switch?

I'm going to do it the normal (proper) way. I think I'll use some of these to switch them on and off.

[TobyJug]

Dont see how you *can* cut out the relay. How are you gonna switch the lights???

A high current switch?

I'm going to do it the normal (proper) way. I think I'll use some of these to switch them on and off.

yep thats the way. u can get 30amp switches too.
also u can get a 2, 4 or 4 base/port switch so u wire the lights in pairs into one switch so they all go on and off at the same time.
I used them on my hilux pick me up in australia and they give a nice color too when they are turned on.... lol
Had two roof switches (1 for 6 front facing lights and 1 for 2 back facing lights) and then 1 for the four bullbar lights..
I will see if I can find the pic's but I had a hard drive crash last year so not sure if I can get them...
I matched the colour up with my radio's lol gonna do the same again when I put a roofrack with lights on the surf and lights on the bullbar..

the only thing is tho u might need to re-build alternator and use 900milly amp battery's lol

anyway hav fun putting the lights on post a pic when they are done...

[rainmaker02]

The only problem using those heavy duty switches is that they will need all the wiring to be capable of handling the current draw.
At least using the relay you can have 'lightweight' cable from the switch to the relay.
I'd leave 'em in, personally

[TobyJug]

The only problem using those heavy duty switches is that they will need all the wiring to be capable of handling the current draw.
At least using the relay you can have 'lightweight' cable from the switch to the relay.
I'd leave 'em in, personally

true I see ur point, I always use 25amp cable all the way through tho..
Same for amateur radio, cb etc.. even if I only use it on lower power I like to use the top cable hehe..
At least that way if I ever upgrade it I have the lot there lol

[Apache]

Yeah, leave the relay in.

Its silly to run heavy duty cable all the way from the battery to the dash and back to the front of the car. The losses you'll get will be far more than using lower duty cable in as short a line as possible between battery -fuse - relay - lamp.

I dont switch my spots separately anyway. I just use the full beam as the 'switch' line for the spotlamp relay. I do have an inhibit switch for the rooflight connector though, as plod dont like you using them on the road.

[Slugsie]

I dont switch my spots separately anyway. I just use the full beam as the 'switch' line for the spotlamp relay. I do have an inhibit switch for the rooflight connector though, as plod dont like you using them on the road.

I thought about adding in a two way switch that allows me to select either using the main beam as a switch, or manually without main beam having to be on.

[Apache]

I always wonder why you would ever put spotlights on without main beam though...

[roylittle0]

Just to set the record straight a 55-watt spot light at 12-volts draws 5-amps (by calculation "P (watts) / V (volts) = I (amps)" basic ohms law)

Therfore 4 lamps will draw 20-amps, if you are using a 1.5mm Tri-Rated cable (automotive cable) which is 16awg (American Wire Guage) this will have a Nominal Overall Diameter of 3.2mm including insulation and has a current rating of 21-amps.

Edit: Just had a better read at the post and i now see you want 6 lamps, thats 30-amps, the Current carrying capacity of 2.5mm cable is 30-amps, therefore the cable on the e-bay item should be 2.5mm CCA, this will have a Nominal Overall Diameter of 3.65mm including insulation

I would recoment splitting the circuit into 3 and having 2 lights on each 20-amp relay using a 1.5mm cable, install all 3 relays in the engine bay and run smaller cables into the cab for the switches, remember you will need atleast a 2.5mm earth cable or run 3 seperate cables

As Apache pointed out, 30-amps is alot to switch especially on DC and i would not recomend this, use a relay they have better contact seperation and are protected from back emf by a diode

Also, basic electrics dictate thatwhat goes in must come out, so the earth cable should always be the same as the supply cable

[roylittle0]

Just had a little thought that most of the time you will or should be running the lights with the engine running then the charging voltage will be somthing like 13.8-volts ish, that will actually give a running current of 4-amps for one lamp at 55-watt, therefore 6 lamps will be 330-watts @ 13.8-volts = 24-amps.

Therefore 2.5mm cable will be no problems at all.