FYI FORD MustangSteve's Ford Mustang Forum / Hooking CAA power wires, gauge question?

**Posted by RTM** 10/20/2024 11:43 AM

When I look up what a 20 amp fuse it states it one should 12 gauge wire. My problem is I don't have 12g wires coming out of my fuse block. I think they are all 18g. I want to run the CAA right to my extra fuse blocks and eliminate their inline fuses. Well the inline fuse has nothing to do with my question. Just thought I would mention my game plan.

**Posted by TKOPerformance** 10/21/2024 6:12 AM

You really do need a 12 gauge wire for a 20 amp circuit. Is there a way to change the wire at the fuse block to make it 12 gauge? Alternately you can always use a relay and use the 18 gauge wire as a trigger.

**Posted by RTM** 10/21/2024 6:33 AM

TKOPerformance wrote:
You really do need a 12 gauge wire for a 20 amp circuit. Is there a way to change the wire at the fuse block to make it 12 gauge? Alternately you can always use a relay and use the 18 gauge wire as a trigger.

I need to research changing the fuse connection. Not sure if I can buy the connectors needed. I'm sure someone sells them. I just have to figure out what to search for. lol

Even if I trip a relay I need to figure out where I can pull power from.

**Posted by Rufus68** **Online!** 10/21/2024 8:30 AM

It is not as simple as gauge vs amps. You also need to factor in length of wire. Here's a chart that shows you don't need 12 gauge until the wire is 20 feet long.

**Posted by RTM** 10/21/2024 9:08 AM

Found the fuse block connectors.

**Posted by RTM** 10/21/2024 9:16 AM

Rufus68 wrote:
It is not as simple as gauge vs amps. You also need to factor in length of wire. Here's a chart that shows you don't need 12 gauge until the wire is 20 feet long.

According to the chart I could use 18g. I'm less than feet of wire.

**Posted by Rufus68** **Online!** 10/21/2024 9:37 AM

I thought that chart would help us understand some of the wiring we find in our cars.

**Posted by RTM** 10/21/2024 5:32 PM

The wires out of the fuse block are 14g. I'll just tap into those.

**Posted by TKOPerformance** 10/22/2024 5:49 AM

For me, it would also depend on whether or not the circuit is running continuously at close to 20 amps or not. For example, if what the circuit powered had say 18 amps at in rush, but ran at 10 I'd be a lot less concerned. IMO, I don't care if the distance was 6" I wouldn't use an 18 gauge wire in a 20 amp circuit. 14 gauge I think would be fine though. The issue you get with some wiring is without knowing how thick the insulation is its hard to know exactly what gauge the wire really is underneath.

**Posted by RTM** 10/22/2024 6:54 AM

TKOPerformance wrote:
For me, it would also depend on whether or not the circuit is running continuously at close to 20 amps or not. For example, if what the circuit powered had say 18 amps at in rush, but ran at 10 I'd be a lot less concerned. IMO, I don't care if the distance was 6" I wouldn't use an 18 gauge wire in a 20 amp circuit. 14 gauge I think would be fine though. The issue you get with some wiring is without knowing how thick the insulation is its hard to know exactly what gauge the wire really is underneath.

I measured the wire strands themself to confirm the gauge.

As I'm progressing with my electrical wiring skills and feeling the pride after redoing the engine bay, I'm most likely going to order the new fuse box clips and run all new12g wire to the AC. I'm not liking the spliced idea of 12g to 14g, even though it should be fine. The only question then is do I leave the CAA inline fuses in place with a fuse wire from the fuse block. Again I'm leaning towards a cleaner look and only have one fuse on those wires. Plus if I left the inline fuses in place I would have to get behind the dash to check or change them.

**Posted by Rufus68** **Online!** 10/22/2024 7:26 AM

I think your decision to run 12 gauge wire in a fuse block is solid. That said, What component of the AC is pulling 20amps DC? The compressor pulls nothing DC. The compressor clutch only powers an electromagnet with DC which I know is much less than 20amps. That only leaves the blower motor. No way that pulls a constant 20amps even on high. What am I missing? (Just trying to follow along)

**Posted by BobE** 10/22/2024 7:39 AM

There are several factors that impact the current carrying of wiring that I won’t get into. The chart that Rufus68 provided is a good guide to follow. However, for a 20 amp fused circuit, I would try to use 14 gauge wire for my own comfort.

**Posted by TKOPerformance** 10/22/2024 2:49 PM

RTM wrote:
TKOPerformance wrote:
For me, it would also depend on whether or not the circuit is running continuously at close to 20 amps or not. For example, if what the circuit powered had say 18 amps at in rush, but ran at 10 I'd be a lot less concerned. IMO, I don't care if the distance was 6" I wouldn't use an 18 gauge wire in a 20 amp circuit. 14 gauge I think would be fine though. The issue you get with some wiring is without knowing how thick the insulation is its hard to know exactly what gauge the wire really is underneath.

I measured the wire strands themself to confirm the gauge.

As I'm progressing with my electrical wiring skills and feeling the pride after redoing the engine bay, I'm most likely going to order the new fuse box clips and run all new12g wire to the AC. I'm not liking the spliced idea of 12g to 14g, even though it should be fine. The only question then is do I leave the CAA inline fuses in place with a fuse wire from the fuse block. Again I'm leaning towards a cleaner look and only have one fuse on those wires. Plus if I left the inline fuses in place I would have to get behind the dash to check or change them.

I personally hate inline fuses. I really try to have fuses either in the fuse panel or in/near the device. My fan for example has a 40 amp fuse in a fuse holder which mounts with a screw right next to the relays for the fan. Its clean and I know where it is. I'm okay with that. My amps use fuses which are mounted on the same board as the amps (these are also big fuses in nice looking holders).

**Posted by RTM** 10/22/2024 6:42 PM

Rufus68 wrote:
I think your decision to run 12 gauge wire in a fuse block is solid. That said, What component of the AC is pulling 20amps DC? The compressor pulls nothing DC. The compressor clutch only powers an electromagnet with DC which I know is much less than 20amps. That only leaves the blower motor. No way that pulls a constant 20amps even on high. What am I missing? (Just trying to follow along)

The fan had a 20amp inline fuse and the ECU has its own power line with a 20amp fuse. I'm sure the ECU doesn't draw 20amp but then again, I'm not the brightest electrical guy. Learning a lot as I go. First time I've ever done anything like this electrically, on any kind of car.

**Posted by Rufus68** **Online!** 10/22/2024 7:37 PM

What gauge wire is feeding the fan? Is it 12 gauge? I've replaced 2 blowers in the last 2 years in later model cars. Neither had wires that were 12 gauge.

Regardless, having a bigger wire doesn't hurt anything. The original question was what size wire was needed.

**Posted by RTM** 10/23/2024 5:33 AM

Rufus68 wrote:
What gauge wire is feeding the fan? Is it 12 gauge? I've replaced 2 blowers in the last 2 years in later model cars. Neither had wires that were 12 gauge.

Regardless, having a bigger wire doesn't hurt anything. The original question was what size wire was needed.

You know I never confirmed that the two power wires on the CAA were 12g. I just assumed they were. I won't be able to check until next week now. Off on vacation.

**Posted by RTM** 10/30/2024 4:28 PM

I finally got one of the clips removed from the fuse block. Hard to remove something when you don't know what style clip it is and your eyes are not what they use to be. Lol

Dies any one know who makes this clip? I'm still looking but haven't found it yet.

**Posted by RTM** 10/30/2024 5:09 PM

Ordered these

**Posted by RTM** 11/09/2024 9:29 AM

The connectors were suppose to arrive yesterday and they did not get delivered. Amazon is now saying they will arrive on the 22nd. I was really hoping to finish the wiring this weekend.

The same just happened to a mountain bike frame I ordered. It to had a delivery date that was Nov 4th. Now it looks like it could be an 8-10 week delivery time because it went by boat and this was USPS from Northern Mariana Island. Seller claims he did not know USPS ground would take this long.

Maybe I'm just spoiled with getting things so quickly. Lol

**Posted by RTM** 11/23/2024 1:38 PM

Sadly the clips should have been delivered last night and the delivery date got bumped out again to the 28th. Was really hoping I could finish the wiring this weekend.

Just had pretty the same thing happen with an eBay purchase. Ended getting a refund on the eBay item and the seller claims it's still on its way.

Still waiting on the metal clips for the contour fan plugs I bought with the fan controller. Seller forgot to box them. He did send them out and may be here today. Having bad luck buying things lately.

**Posted by RTM** 11/23/2024 5:38 PM

The clips were in the mail box when the wife checked the mail. Maybe Amazon will send me more. Lol

I was able to wire the 12g wire for the AC system directly to the fuse block. I'm very happy. May try to test start the it tomorrow with the key.