Need to know how to connect a relay?

[GBBiker]

I've noticed a few posts asking how to connect relays and a few problems that have occured due to incorrect wiring.

This is how to connect up a 12vDC 4 pin aftermarket automotive relay.



Remember to fit an appropriatly sized fuse.

To work out what size fuse you need, divide the total wattage of your ancilliary items by the voltage.

Example

2x 55 watt spotlamps = 110 watts.

110w / 12v = 9.167Amps

Allow 40% for initial surge = 3.667A

9.167A + 3.667A = 12.834A

Fit 15A fuse

I know it will look a little complicated to some, but it really is a simple calculation. Don't forget to allow for the initial surge when selecting your fuse size - you will be amazed how many 'pros' can't figure out why a 10A fuse blows when fitted to 2x 55w spots

[ake]

The switch wire to pin 86 should also be fused if taking it from the battery as shown, 2 or 5 amp would do

[GBBiker]

The switch wire to pin 86 should also be fused if taking it from the battery as shown, 2 or 5 amp would do

It's not completely necessary, but it is a good idea I agree. TBH, a 2A fuse will be more than enough, you will only be drawing mA to power the coil.

There you are, changed it