Relay Wiring - 18GA Is Good?

[chibahawk 10+ year member]

Okay will someone just check out what I want to run?

I've got an 18G wire running direct off the battery that I want to connect into:

-2 CCFL tubes running on a switch

-4 CCFL tubes and a Music Interface device running off a switch

-4 PC fans in amp rack

-2 amps

I'm doing all this through the standard SPDT or SPST Relay.. wondering if 18AWG is good enough for all this stuff and whether or not I have made any mistakes in how I should probably wire it.

Enjoy the diagram.. im bored as kcufff at work

**edit: I've also got a spare inline fuse laying around - 40A. This would be good to use right and where do you think I should place it in the circuit? Thanks..

Click to read more...

 

[Prowler573 5,000+ posts]

Here's Jmac's wiring guide. According to that you'll want to go with 10awg. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

The relay itself acts as a fuse/breaker of sorts so IMO fusing the power line from the battery to the 12vdc input on the relay is redundant.

I'm using a relay to turn on 2 amps, two 20" neon tubes, and one 15" blacklight tube (without all the switches you plan on incorporating) and it isn't fused. Thus far I've had no problems //content.invisioncic.com/y282845/emoticons/thumbsup.gif.3287b36ca96645a13a43aff531f37f02.gif

 

[chibahawk 10+ year member]

sounds good.. ill find some more efficient use for that fuse then.

However.. I think it might be in my interest to find out the amperage of my accessories.. While Jmacs guide says 35 amps is good with 10awg wire.. thats his starting point.. if my total amperage is only like 10-20 I may be good with 18awg..

basically I've got 20 ft. of 18awg wire and I don't exactly want to replace it and have that 18awg laying around... whatcha think?

p.s. i think CCFL tubes draw is only like .5 amps or something.. really not sure though

 

[helotaxi 5,000+ posts]

Here's Jmac's wiring guide. According to that you'll want to go with 10awg. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
The relay itself acts as a fuse/breaker of sorts so IMO fusing the power line from the battery to the 12vdc input on the relay is redundant.

I'm using a relay to turn on 2 amps, two 20" neon tubes, and one 15" blacklight tube (without all the switches you plan on incorporating) and it isn't fused. Thus far I've had no problems //content.invisioncic.com/y282845/emoticons/thumbsup.gif.3287b36ca96645a13a43aff531f37f02.gif

If the relay is in the trunk and you get your +12V from somewhere not right next to the relay, you need to fuse the wire as close to the source as possible to prevent a short before the relay from burning the car to the ground.

 

[Prowler573 5,000+ posts]

If the relay is in the trunk and you get your +12V from somewhere not right next to the relay, you need to fuse the wire as close to the source as possible to prevent a short before the relay from burning the car to the ground.

Fair point.

The relay I'm using is powered off of my distros which it is within 6" of. In the OP's case this could be very different.

+1 for helo.

 

[chibahawk 10+ year member]

If the relay is in the trunk and you get your +12V from somewhere not right next to the relay, you need to fuse the wire as close to the source as possible to prevent a short before the relay from burning the car to the ground.

ok in that case ill definitely fuse this next to the battery...

helo your expertise would be appreciated regarding the 18awg powering those accessories.. its also being run from the front of the car to the relay in the trunk.. what would you suggest as a containable amperage for that size wire?

Thanks

 

[helotaxi 5,000+ posts]

I would probably go with 8-10ga for the amount of stuff you want to run. Inline fuses are easy to find for 8ga. I pull my accessory and remote power off an extra output on my disto block (4ga) and go from there to an ATC fused distro panel (power and ground). Gives me fusing for all the low current devices in the car. WIll be used for fans and maybe some lighting in the new system as well as powering my processors and supplying +12V for my remote relay. Got the distro panel off eBay for like $6. Designed to be used in custom hotrods or boats where all the wiring is custom made.

 

[chibahawk 10+ year member]

hey helo would you happen to know the amperage load for an 18awg wire? seems like it may be around 20A and I may roll with the wire I've got. Cathodes only draw about .35A and I don't think the amps drain much do they?

 

[helotaxi 5,000+ posts]

5A according to every chart I can find.