gon2srf wrote:Two questions:
1. Anyone see any issues with temporarily running the two switches off of one 7.5 amp fused 12 ga. lead? Both accessories are running relays.
2. Is it safe for LOD to provide a back up lighting set up for 2 55 watt halogen lights(don't know exact specs.), a switch, inline fuse but no relay? I'm guessing they do this because they are back up lights and are hypothetically not supposed to be run for long periods of time. I think that kind of current draw warrants a relay?
1) It depends on the current draw of the switches involved. Assuming the switches are either PIAA or standard low amp draw automotive switches, you can piggyback many onto one fuse circuit, as they draw only milliamps for triggering the relay(s). This is one reason why using a relay on a higher current circuit is important - to avoid flowing high current through switches and fused circuit that can heat up from the load. I usually recommend that all the switch power wires for relay-activated light circuits run through one fuse - easy to maintain, and no wasted circuits. With a relay for the light side of the circuit, you can use smaller, 18 gauge wire for the switch wires, to the relay and the fusebox (12 gauge is waaaay overkill, and harder to bend in tight spaces). Regarding the relay itself - 2-55w lights is 110w of draw; divide by the operating voltage (roughly 14V) gives you the minimum amp rating for the relay, in this case 8 amps. Due to resistance fluctuations and voltage fluctuations, most low power light circuits use a minimum of a 15 amp relay, which is what I'd suggest here. And don't forget to put a 15 amp fuse in-line between the relay and the battery...
2) The relay is an electric switch; it connects power (vehicle battery) to a device (lights, in this case) without running all that current inside the vehicle and through the switch on the dash. This way, the high-power side of the circuit remains directly attached to the battery for efficiency and voltage stability, and very little current is used by the switch to activate the relay, protecting the lighter-duty components. ALL halogen/xenon lighting circuits, and any circuit drawing more than a couple of amps SHOULD incorporate a relay in it to increase bulb and switch life, and reduce the possiblilty of fire inside the vehicle if a problem occurs in the switching circuit. My guess is they are using a less-expensive model of imported lights that came with very basic wiring to save on cost - adding a relay (and making sure you have proper wire gauge for all parts of the circuit) is a very wise idea, and will help keep the lights working longer (and brighter).
OK, I'm out of breath now, and you are all falling asleep....but you hit on a favorite topic of mine...
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