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How are relays rated?

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Old Aug 2, 2008 | 07:44 AM
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Default How are relays rated?

Does anyone know how relays are rated for voltage and amps and whatever else they do. I have a relay that used to be run for a 15amp circuit .8gage wire. I am now running a 20amp 1gage wire through it. Will I burn up the relay or can it handle the potential of 5 extra amps? Anyone know?

Relay: 12177235 DOO

30 86
-- --

85 87a 87
-- blank --
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Old Aug 2, 2008 | 07:56 AM
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8 Gauge wire on a 15A circuit, and 1 ga for 20A??
Overloading that relay by 35% is not a good idea. Relay load carrying capability is determined by it's duty cycle, and the size of the components it's built with.
30, 40 A relays are readily available, and not real expensive. I'd use 1 that's rated for the actual load, and environment you will see.[water proof? etc.]

As for the wire size...That's a real ?? The application evidently was not an OEM deal, as those wire sizes are waaay bigger than the relay would ever be able to handle.
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Old Aug 2, 2008 | 08:14 AM
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Are you wiring a fuel pump? I could only assume the larger gauge of wire is to decrease voltage drop. I did the same (sort of) with my car. Everything is 10 gauge copper house wiring with 0 gauge copper thhn for battery cables and alternater wiring. I see 14.7 volts all day long just about everywhere. Even at the fuel pump.
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Old Aug 2, 2008 | 08:29 AM
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^^^^^ LOL! I see i confused some of you. Sorry bout that. I've been pouring over factory wiring diagrams for days now and they list everything in metric wire sizes. So now I think in metric wiring. .8gage = 18gage and 1gage =16gage. So i only increased the size slightly but i am still running potentially more amps.

It is for a remote hatch release. The 2002 harness uses a 15 amp relay but the release on my 3rd gen needs a 20amp feed. So I am just running a thicker feed wire that is fused to 20amps instead of 15amps. It will be a limited use relay so just checking to see if it can handle it.
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Old Aug 2, 2008 | 08:53 AM
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Talking Yep!

A whole new "ballgame" when metrics are intro'd!!
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Old Aug 2, 2008 | 09:01 AM
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Originally Posted by Old Geezer
8 Gauge wire on a 15A circuit, and 1 ga for 20A??
Overloading that relay by 35% is not a good idea. Relay load carrying capability is determined by it's duty cycle, and the size of the components it's built with.
30, 40 A relays are readily available, and not real expensive. I'd use 1 that's rated for the actual load, and environment you will see.[water proof? etc.]
....
40 amp metripack sealed relay kit here: http://www.lsxtune.com/shop/product_...roducts_id/503
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Old Aug 4, 2008 | 10:32 AM
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Still curious how you can determine what amperage a relay can handle. Say I buy that 40 amp relay kit. Does that mean it will function correctly running off a 20amp circuit? The goal here is correctly wire the circuit for the min. and max amps it will ever see. I don't want to go too low or too high. Unless it doesn't matter and this is pointless I'll just solder in a window circuit breaker and call it a day!
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Old Aug 4, 2008 | 10:50 AM
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It's determined by it's rating. If the contacts are rated to handle to handle 40amps and you are using 20 for your circuit then you have room to increase load another 100%. I'm not sure what you mean by wiring the the circuit for the "min. and max amps it will ever see". All you need to worry about is the max value though.
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Old Aug 4, 2008 | 12:33 PM
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Sounds good. Thanks for all the help. I probably will end up running a thicker gage wire to the relay and from the relay to the solenoid. But the 40 amp relay should work fine.
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