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I'm No Expert
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Discussion Starter #1
I bought a few relays for things like fuel pump, bilges, and the banderlog. They are a 30 amp relay but i'm curious what guage wire i need to feed the on/off side. I'm thinking a 18 guage wire should be enough.

Specs off the relay
Coil Voltage: 12V
pull-in Voltage: 6V
Coil resistance: 66 ohms
Nominal current: 160mA
Drop-out voltage: 3.6
SPST contacts: 30A at 12VDC

Is nominal current the amp usage of the coil side of the relay?
 

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I bought a few relays for things like fuel pump, bilges, and the banderlog. They are a 30 amp relay but i'm curious what guage wire i need to feed the on/off side. I'm thinking a 18 guage wire should be enough.

Specs off the relay
Coil Voltage: 12V
pull-in Voltage: 6V
Coil resistance: 66 ohms
Nominal current: 160mA
Drop-out voltage: 3.6
SPST contacts: 30A at 12VDC

Is nominal current the amp usage of the coil side of the relay?
If this will ever see a 30 amp load you want to use 12 or 10 for that matter. 18 gauge will get HOT with 10 amp loads 30 will be BAD!

I think I read it wrong, the signal side of the relay can be run in 18 gauge with no problems but the load side needs to be sized according to the amp load.

Brandon
 

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steelcomp was here
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If this will ever see a 30 amp load you want to use 12 or 10 for that matter. 18 gauge will get HOT with 10 amp loads 30 will be BAD!

I think I read it wrong, the signal side of the relay can be run in 18 gauge with no problems but the load side needs to be sized according to the amp load.

Brandon
Correct. The coil side isn't even pulling an amp and 18G would be plenty. ON the load side, it depends on the load. Typically, 15a or lower use 14g, 20a use 12ga, and 30a use 10ga.
 

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I'm talking about the gauge needed to feed the on/off switch side... the side that a switch usually hooks too to activate the relay. Sounds like 18g is fine for that.
Yep, that's correct. You could go with a much smaller wire but I wouldn't recomend it in a boat just so there's strength to the wire.
 

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I'm No Expert
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Discussion Starter #8
Yep, that's correct. You could go with a much smaller wire but I wouldn't recomend it in a boat just so there's strength to the wire.
I doubt i'll run 18 to them, probably 16... I always take what they recommend and step it up. Example, autometer recommened 18 for there guages between the sender and the guage... I ran 16. Just makes me feel alittle better. :D
 

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I doubt i'll run 18 to them, probably 16... I always take what they recommend and step it up. Example, autometer recommened 18 for there guages between the sender and the guage... I ran 16. Just makes me feel alittle better. :D
Whatever you're comfortable with that'll work is good. I've used as small as 24 gauge wire to trigger relay's.
 

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your talking about the control circuit of a relay, you can use 18 gauge if you want, your could even use smaller if you wanted, but i also like to go just slightly bigger because of the distance the current must travel from the front to the rear which is why i think 18 is perfect. but the load that it takes to control the relay would be like 1 of the bulbs for your gauges, its next to nothing. the reason why they are so so much safer than running it straight to a switch. i still can't figure out why anyone would think to run anything directly to a switch....everything on my boat has a relay. i've seen a boat on fire and you have absolutely nothing when its over...nothing. not worth it.

AP
 
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