Light Relays???

MackAttack · Nov 9, 2005

I need to hook up some lights to prevent the loader shadows. Do I need to use relays ?? If so how come?? I plan to use a 6 switch box which is designed to work with multiple lights on a police car. This box has one main power feed and the switches each have a 20 amp fuse. Do you think will be okay?

My mechanic at the dealer stated to me that the alternator on my TC35D is more than capable to handle the load.

I come here to the top of the mountain to seek advice from a wise man. /forums/images/graemlins/grin.gif /forums/images/graemlins/confused.gif /forums/images/graemlins/smirk.gif

MikePA · Nov 9, 2005

I installed 2 sets of lights, one set facing the rear and one on the ROPS facing front. The 2 lights facing to the rear are hooked up to the power feed that NH uses for their optional work light. I used an outdoor toggle switch rated for the amps the lights draw to control them.

For the set of lights on the ROPS, I purchased a Hella driving light kit that came with the lights, a switch and a relay. I ran a separate, fused, feed directly from the battery, to power them. Since their instructions indicated a relay should be used, I used the one they provided. I believe that a relay is used so that the full current draw doesn't have to go through the switch, making it a safer installation. I imagine if your switches are rated for the current the lights will draw, you'll be OK without a relay. Hopefully, someone who isn't as electrically challenged as I am can confirm, or correct, what I've typed.

BobReeves · Nov 9, 2005

It's all about contact ratings....

If your lights draw 20 amps and you want to turn them on with a 5 amp switch you will need to use a 20 amp (preferably higher) rated relay and use the switch to energize the relay. If your lights draw 10 amps and you use a 20 amp switch you can hook them directly to the switch.

Volts times Amps = Watts, Amps = Watts divided by Volts, 30 Watt bulb at 12 Volts would be 30/12 = 2.5 Amps. Two of these lights would total 5 Amps etc.

Always try to have the relay/switch contacts rated 25 to 50% over the max current of the load (light bulb(s)) and use a wire chart to determine the minimum wire size to use when hooking everything up.

PineRidge · Nov 9, 2005

If you reside in the colder climate and want nice warm heated switches when you reach for them then you can forget the relays. /forums/images/graemlins/wink.gif

If it were me the relays would not be an option, they would be a must.....

jinman · Nov 9, 2005

I think there are lots of factors that effect the longevity of a direct switch circuit in a low voltage DC circuit. Switch bounce and contact resistance are two that come to mind. When the switch is new, it will work fine, but over its life, due to bounce of the contacts and arcing, the switch will deteriorate and contact resistance will increase causing the contacts to weld themselves together. It you have an expensive switch with very good contacts, it will take a long time to fail, but I would not rely on the switch in a high current DC application above more that a couple of amps. I'd go with the relay. It's a little more work, but a much more elegant solution that will outlive the switch alone.

Soundguy · Nov 9, 2005

A relay saves copper and switch rating size. That is.. you can use a small switch and small gauge wire run fromt he op compartment of the tractor to the engine compartment to then control a relay and a shorter piece of heavy gauge wire.. vs running that heavy gauge wire the whole way and having a monster switch inline.

Soundguy

MackAttack · Nov 9, 2005

Do I need a relay for each light or can I hook up more than one light to a relay??? Where can I get relays??? And how do I hook them up??

I thought about hooking up the following lights- 2 on the canopy facing forward, 2 facing rear, a little dome light under the canopy and a strobe on the top of the canopy. What would you do???

The link to the switchbox I'm using is below. it uses a 10g wire to feed the power and has a wire for each switch. In addition, it has a separate wire that hooks up to the ignition to power the LEDs for the switchs and labels.

http://www.galls.com/style.html?assort=general_catalog&style=SE083&cat=2664

PineRidge · Nov 9, 2005

Inexpensive relays and relay sockets click here

Size the relay to work as many lights as you need.

daTeacha · Nov 10, 2005

Just wondering, where are you guys mounting all these lights? My ROPS installation instructions specifically and emphatically prohibited drilling holes in the thing or welding or screwing stuff to it, so I had to rig up some angle iron clamps and mount the lights on the angle. Are you drilling the ROPS or doing something else? Is it safe to drill a typical OEM ROPS? Mine's a factory part from the dealer installed on a tractor that predates the requirement.

Soundguy · Nov 10, 2005

IMHO.. you never modify a rops.. that includes drilling, torching, cutting.. bending.. etc. About the only thing you can do is use brackets and clamps that bolt around it in a friction mount style.

U or D bolts are examples.. When I have to mount stuff to rops.. I build a bracket.. mount the stuff to that.. then use U or D bolts to attach the bracket to the rops..

Lots of people DO drill their rops.. that's a personal choice between you, your familly, your estate lawyer, and your life insurance policy.. any advice you reviever other than to follow the manufacturer/dealer recomendation of not modifying your rops should be viewed very carefully.

Soundguy