grant1985 · May 17, 2014

Hi again. Yet another post lol. Thing is I fitted some 100w spot lights to my roof bar today via a relay and a fuse up to a switch. They didnt work unless I removed the relay so can I get away with just using the fuse seen as I only use them for off roading or is a relay required. No matter what relay I use they stop working? Any advice etc would be appreciated. Thanks

Pikey · May 17, 2014

Then you've wired them wrong.

Talk us thru the setup which wire to which terminal etc. Fuse rating, Relay rating, number of lights etc.

oxides · May 17, 2014

"via a relay and a fuse up to a switch. They didnt work unless I removed the relay" This sounds wrong to me. Wiring should go via the fuse and relay, switch from live to other terminal on relay. Did you remember the earth on the relay coil? There's plenty of articles on using relays on this site......

Pikey · May 17, 2014

oxides said:
"via a relay and a fuse up to a switch. They didnt work unless I removed the relay" This sounds wrong to me. Wiring should go via the fuse and relay, switch from live to other terminal on relay. Did you remember the earth on the relay coil? There's plenty of articles on using relays on this site......

egg zacker lee

Thas why I asked him to describe wot he's done with the bugger..

Am still waiting.

Just thinking out loud but if he's fitted 4 100W bulbs, thru 1 relay did he rate everything to take a minimum of 30Amps??? Cos if he's used a 20Amp relay & a 20amp fuse he's gonna be buggered...

grant1985 · May 17, 2014

Yeah I copied a post from here showing the wiring and everything. All was exactly the same except I was using a on of switch rather than a on off on. The wiring is sufficient as its from work on the machines not sure of the rating but its bigger core than standard. The relay was from a land rover light relay and the fuse is 20 or 30a cant remember off the top my head. Had the lights going on 1 terminal. Live from the battery, earth to the truck, and nothing. Soon as I remove the relay and use with just a fuse its fine. Not a prob.

Pikey · May 17, 2014

grant1985 said:
Yeah I copied a post from here showing the wiring and everything. All was exactly the same except I was using a on of switch rather than a on off on. The wiring is sufficient as its from work on the machines not sure of the rating but its bigger core than standard. The relay was from a land rover light relay and the fuse is 20 or 30a cant remember off the top my head. Had the lights going on 1 terminal. Live from the battery, earth to the truck, and nothing. Soon as I remove the relay and use with just a fuse its fine. Not a prob.

So you don't know what the wire is rated at. the relay is operating at it's ,maximum rated thruput the fuse is seriously under rated and the switch you ran it all thru is probably rated 5 or 10 amps.

try this sum. [Watts dived by Volts equals Amps] Assuming you have used 4 lamps. 400W / 13.5V = 29.63Amps. I'd buy a fire extinguisher if I was you.

grant1985 · May 17, 2014

Oh well il just rip the crap out and start again I guess. The wiring I got is so called more than ok from the electrician at work the fuse is a 30a for sure but like I said I cant say what the relay is I know its standard land rover headlight rating as thats what it is from. And the switch isnt nothing special but im waiting for my new switch to arrive from ebay which will then be a on off on. If it arrives lol

Pikey · May 17, 2014

grant1985 said:
Oh well il just rip the crap out and start again I guess. The wiring I got is so called more than ok from the electrician at work the fuse is a 30a for sure but like I said I cant say what the relay is I know its standard land rover headlight rating as thats what it is from. And the switch isnt nothing special but im waiting for my new switch to arrive from ebay which will then be a on off on. If it arrives lol

When you redo it. you need

Live feed direct from the batteyr, thru a fuse to the relay.

Live feed thru the switch to trigger the relay the current is miniscule as all it does is activate a switch inside the relay.

A wire from relay to a good earth point

Finally the feed wire from relay to lamps.

Make sure that the earth wire on the lamps and relay is rated at least as highly as thewires used for the Live feed to the lamps.

grant1985

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