Thoughts on doubling up electrical wires

[Grumblebuns]

I'm in the process of wiring up my Spal radiator fan and I'd like to maintain the stock wiring color standard as much as possible. The original B/G and Y/G wiring circuit to the fan appears to be 14 wire (equivalent to 18 AWG) which to me is pretty underwired even for the original fan much less for the higher output Spal. I'd prefer to use a 44 strand (equivalent to 12 AWG) wire instead to eliminate any voltage drops. Unfortunately the largest size British Wiring offers in the B/G and Y/G colors are the 28 strand (equivalent to 14 AWG).With the short wire run from the fuse box to the relay, the 28 strand wire probably will not cause a problem. My thought is to run an equivalent "12 AWG" wire is to double up on a 14 strand and a 28 strand to create a 42 strand B/G or Y/G run to the relay. Besides the potential DPO aspect of this, anyone see a technical problem with this?

Joji Tokumoto

[Kendo]

14AWG is good for 15A. How much does the Spal draw?

[Kendo]

And if you do double it, then keeping the right color code sounds like the thing to do.

[jbcollier]

I would go with the larger wire size rather than running two wires.  Either way it is noticeably non-standard and a single wire with a connection at either end is more reliable than two wires with four.

[Grumblebuns]

Spal recommends either 30 0r 40 amp fuses for their "high performance" paddle style fans, see photo. If I had a clamp on ammeter I would check the running current on the bench but I don't.  I ran 12 gauge orange wire for my last radiator fan swap out on another TCS; I'll ponder this further.
 

[dakazman]

  Hate to throw another monkey in the wrench , but have you thought about a fan control kit with a 40amp relay? It can also run dual fans for further cooling ?
  This kit has a 12 gauge feeder.  I would also stay away from dual wires.
Dakazman

[califkid_66]

I just installed my spal fan I just hooked it up to the original fan wiring
Should I be worried
One thing I noticed is the wiring on the spal fan is the same gauge as the original fan so
I don’t see the purpose of doubling or putting bigger wires unless you take the fan apart to change wires in it if it pulls so much power why are the wire so thin
Please let me know what you guys think
I just ran the fan a couple seconds to see if it worked
And noticed where I bought it says 25 amps at 13 volts

[jbcollier]

You can’t tell how thick the wire is without cutting off the insulation.

Use an ammeter and measure the current.  If it is over 10-ish amps continuous, then you need larger wire — yes it may be “rated” to 15 amps but you need a safety margin.

[califkid_66]

You are right Jb I didn’t remove the insulation ,the end of the fan wiring comes with a plug with two
Pins I just used U type connectors but now I’m thinking of cutting the plug off and putting tab connectors so that’s gonna give me the chance to really see what size wires are on the fan and I’ll go from there

[jbcollier]

You could also run the fan for 5 minutes and feel the wire. If it is warm, it’s too thin.

[Grumblebuns]

There seems to be a discrepancy on fuse requirements between the Spal website and what is printed on their packaging. The website has a 25 amp fuse requirement while the packaging has a 40 amp fuse. As far as I remember, there was no installation sheet included with the fan however 40 amps seemed a bit excessive to me so I'm tending to believe that the 25 amp fuse requirement is more reasonable.

In my post I stated that the stock wiring (B/G and Y/G) for the radiator fan appears to be 14 strand wire equivalent to 18 AWG. According to a wire amp capacity chart, the amp limit will be less than 10 amps at 4 feet wire length which I suspect will be pretty much at the limit for the stock wire. The Spal off the top of my head looks to be using 14 AWG which will handle 15 amps at 6 feet length.

In regards to your current setup, I don’t have the training or experience to tell you definitely if you’re exceeding the limit for current rating but with a 25 amp fuse requirement for the fan, I suspect you’re very close. The other things to consider is the voltage drop with the smaller than optimum wire size affecting fan speed and heat up of the wiring. You also have to remember that you are using the original 30 amp fuse in the fuse box for protection and not the recommended 25 amp fuse.

At the very least, I would look into running the fan through a relay.

https://www.lotuseuropa.org/LotusForum/index.php?topic=1062.0

https://jascoautomotive.com/automotive-wire-amperage-capacity-chart/

[Kendo]

Doesn’t the stock circuit complete with the temperature switch connecting to ground? As the other half of the circuit, that ground line should also get beefed up to the current rating the power feed gets. Over the years I’ve seen many posts about bigger power feeds and power relays for fans, headlights, and windows. But it just occurred to me that I haven’t seen discussion of increasing the ground line.

[Grumblebuns]

Power in should equal power out, so the ground wire size should equal the number of hot wire(s). Controlling the fan circuit through the Otter switch will reduce the longevity of the switch due the high current arcing during switch operation. That's the reason a relay is recommended to handle the current.

[jbcollier]

The rad fan switch controls the fan relay.  It is not in circuit with the fan.

There are various motors used in Spal fans.  Amp draw ranges from the teens to the forties (!).  Boxes can be generic so double check on the Spal website with the actual part number.

High power fans draw more, a lot more, amps on start up.  A fan that draws 14 amps continuous might peak above 30 on start up.  You can use a fan controller with “soft” start instead of a relay to alleviate this issue.  It also is kinder to your alternator and battery.

[Grumblebuns]

I'm trying to remember if the S2s have a radiator fan relay as stock. I know that the TCs do not, the fan is controlled directly off the Otter switch.