AWG, FSM and the late 60s

[vdk2010]

I'm in the middle of documenting the wiring harnesses. Take it apart, write down the colors, lengts, connector type etc. and I was surprised about how thick the factory wiring actually is. (14 AWG and bigger). Yesterday I checked all the wiring diagrams and saw, all the wires are labeled with much thinner gauge then they actually are.

Now, whom should I trust, the engineers and their labeling in the FSM or the factory and the actual wire thickness they used?!

I would tend to trust the FSM and use 16 AWG for most wires and a few 12 and 10 AWG for the thicker power leads and 2 AWG for the ground cable, but what would you guys do?

Another reason I would choose the "thinner" wires is, that it's nearly impossible to find all the colors in 2,5mm² (14 AWG) and up. The most colors are available in 1,5mm² (16 AWG).

 

[commando1]

This isa no-brainer.
For me at least.
Actual.
And, incidently, one factory that I know of that manufactured wiring harnesses, used all white wire and dyed them to get the colors.
And the cable dye machine also would apply the white "tracer" stripe if that particular wire needed it.

 

[cantflip]

I would lean toward the opposite. A larger wire is safer in the sense that it would not be as likely to drop voltage or overheat if poop went wrong...

 

[commando1]

I would lean toward the opposite. A larger wire is safer in the sense that it would not be as likely to drop voltage or overheat if poop went wrong...

I read Vodka's post to say the the actual wire used was thicker than spec'd in the manual. No?

wassurprised about how thick the factory wiring actually is. (14 AWG and bigger). Yesterday I checked all the wiring diagrams and saw, all the wires are labeled with much thinner gauge then they actually are.

 

[cantflip]

I'm a dumbass...
Thank you.

 

[commando1]

I'm a dumbass...
Thank you.

My pleasure.

 

[vdk2010]

Correct, Stan. The actual wire is much thicker then specked in the fsm.

 

[vdk2010]

I would lean toward the opposite. A larger wire is safer in the sense that it would not be as likely to drop voltage or overheat if poop went wrong...

Generally, I agree. The bigger, thae saver it is. But the used wires seem totally overkill to me after reading the FSM. Does anyone know what wire gauge painless uses for their harnesses?

 

[OneEyed]

Is it the actual wire itself that is thicker or the insulation on the wire? Bigger wire is typically better. The only downsides I could see is takes up more space and costs more..

 

[vdk2010]

It's the actual wire. The insulation is also way thicker then today, but the newer insulation material is better, so that's ok.

Most of the main wires on the engine compartment harness is labeled with 18 gauge in the fsm but is actually ~1.86mm in diameter (only the wire without insulation), which is 13 gauge.

 

[Big_John]

It's the actual wire. The insulation is also way thicker then today, but the newer insulation material is better, so that's ok.

Most of the main wires on the engine compartment harness is labeled with 18 gauge in the fsm but is actually ~1.86mm in diameter (only the wire without insulation), which is 13 gauge.

You can't measure stranded wire like that.

The AWG (American wire gauge) is based on solid wire. So if you were to measure a solid piece of wire, then yes, you would be right in identifying that wire as 13 gauge (BTW, that's an uncommon size).

But! Since you are dealing with stranded wire, you have to do some other math to come up with the size. You combine all the average wire cross sectional area of each strand and then compare it to the solid wire cross sectional area. Basically... A piece of stranded #14 wire is going to seem larger than a solid #14 wire.

I've always found the wire size to be very accurate in the FSM. You have to compare apples to apples though.

 

[vdk2010]

It makes sense as you say it. It have to be bigger with many small leads compared to one solid wire. But I took that information from many different charts I found online. But as you say, they don't say on them what type of wire. Maybe solid.

Then it would be best to stick with the informations given in the FSM on the wire sizes.

Thanks John!!!

 

[Big_John]

It makes sense as you say it. It have to be bigger with many small leads compared to one solid wire. But I took that information from many different charts I found online. But as you say, they don't say on them what type of wire. Maybe solid.

From the Wikipedia link: American wire gauge - Wikipedia

The AWG tables are for a single, solid, round conductor. The AWG of a stranded wire is determined by the cross-sectional area of the equivalent solid conductor. Because there are also small gaps between the strands, a stranded wire will always have a slightly larger overall diameter than a solid wire with the same AWG.

AWG gauges are also used to describe stranded wire. In this case, it describes a wire which is equal in cross-sectional area to the total of all the cross-sectional areas of the individual strands; the gaps between strands are not counted. When made with circular strands, these gaps occupy about 10% of the wire area, thus requiring a wire about 5% thicker than equivalent solid wire.

Stranded wires are specified with three numbers, the overall AWG size, the number of strands, and the AWG size of a strand. The number of strands and the AWG of a strand are separated by a slash. For example, a 22 AWG 7/30 stranded wire is a 22 AWG wire made from seven strands of 30 AWG wire.

 

[BJS racing]

Generally, I agree. The bigger, thae saver it is. But the used wires seem totally overkill to me after reading the FSM. Does anyone know what wire gauge painless uses for their harnesses?

Actually I know very well what we use in our harnesses. Once again it is all dependant on what the circuit is. But also you have to take into account that the grade of wire used back then compared to what we use now. Most of the time we will still use the same size wire that the factory used even though we could likely go to a smaller wire to do the same job since we use TXL grade wire and it will carry more current. This plays into the safety factor as we mentioned earlier incase someone does something different than stock. Our 14 gauge wire can carry up to 35 amps where as the factory wire at most could carry 20-25 amps. If in doubt go bigger.

 

[vdk2010]

Actually I know very well what we use in our harnesses. Once again it is all dependant on what the circuit is. But also you have to take into account that the grade of wire used back then compared to what we use now. Most of the time we will still use the same size wire that the factory used even though we could likely go to a smaller wire to do the same job since we use TXL grade wire and it will carry more current. This plays into the safety factor as we mentioned earlier incase someone does something different than stock. Our 14 gauge wire can carry up to 35 amps where as the factory wire at most could carry 20-25 amps. If in doubt go bigger.

Thanks for the clarification! I went with TXL (FLRy) wire as well. And there are Conversion table from AWG to mm² I used to find the correct metric counterpart to the wires described in the FSM.

Do Painless sell bulk wire? I have trouble finding some colors here in Germany.

 

[Big_John]

Try these guys. I have bought their cloth covered wire for my 53. They have a good assortment of wire and terminals.

Rhode Island Wiring Service Inc.

 

[BJS racing]

Thanks for the clarification! I went with TXL (FLRy) wire as well. And there are Conversion table from AWG to mm² I used to find the correct metric counterpart to the wires described in the FSM.

Do Painless sell bulk wire? I have trouble finding some colors here in Germany.

We offer 25' and 50' rolls of wire in different colors and sizes. If you look at page 92 of our PDF catalog on our website that will show you all the wire we offer.

 

[MrMoparCHP]

I just got new harnesses, Evans does engine and forward lamp, M & H does them all. My dash harness was in good shape, saved it, the others all new.


Alan

 

[vdk2010]

I found that the '69 Imperial is not "good" for using an universal harness of any Manufacturer. I will use relays on more circuits then the factory did and will ad several circuits for accessories and stereo. So I decided to make my own harness instead.

And you learn a LOT about your car, while studding the OEM harness, wiring diagrams and searching for options to add circuits and relays! That's complicated (at least for me) but a lot of fun!

 

[cantflip]

I found that the '69 Imperial is not "good" for using an universal harness of any Manufacturer. I will use relays on more circuits then the factory did and will ad several circuits for accessories and stereo. So I decided to make my own harness instead.

And you learn a LOT about your car, while studding the OEM harness, wiring diagrams and searching for options to add circuits and relays! That's complicated (at least for me) but a lot of fun!

By modern standards, the wiring of these cars leave much to be desired in the circuit protection department...

I have had some similar thoughts, but I won't let myself tear a car apart unless I have the ability to finish the job in short order... It's a space consideration for me.