Alantf

Water Warrior 2 · 07-20-2014, 12:52 AM

Got a simple question and need an answer from the best source I know. Is a 18 gauge wire adequate to run 10 amps a distance of 3 or 4 feet at 12 volts? Got a little project in mind for the Ford in my life.

alantf · 07-20-2014, 04:27 AM

Sorry, but I don't know what 18 gauge is. This must be an American/Canadian terminology. In Europe we use the metric sizes (and have done for many years) 1.5mm² would be the minimum size for 10a (if not in continuous use), while 2.5mm² would be good for up to 32a.

Just as a guess - America uses 120 volts, as opposed to Europe's 240 volts, and England's domestic lighting circuits are 5a. That means that American lighting circuits are 10a (W=VxA). So, if you find out what gauge the Americans use for domestic lighting, that should be ok for you.

mole2 · 07-20-2014, 03:24 PM

In the US we breaker/fuse 14 gauge wire at 15 amps for 120v.

This chart is for 12v.

raul10141964 · 07-20-2014, 05:43 PM

12 gauge for 120V 20A outlet

5th_bike · 07-20-2014, 06:52 PM

Well 18 gauge can handle it (max 16A for a bare wire with sufficient cooling), but (assuming a total of 2 meter of wire, 1 meter each way) you will loose more than 0.1 V per wire, >0.2V total. The wire will warm up a bit, with 1W of heat dissipating.

18 gauge is not recommended to sustain a 5A supply of power, only 2.3A.

If you want to stay with it for safety, by all means use the 18 gauge. Do wear safety glasses and have a fire extinguisher ready.

For 5A it's safer to use 14 gauge or larger.

Or, double up on the 18 gauge, then you should be OK.

Water Warrior 2 · 07-20-2014, 07:56 PM

Oh my, I have opened up a can of worms.
I will start over. I want to add a continuous draw system to my 12 volt Ford Ranger. Maximum of 10 amps.
Here is the reason. Ford in their wisdom has no way to shut off the Air conditioner compressor and still retain all the air flow control. By switching the AC compresor off I can retain full control of all air flow positions. I want to add a switch to the AC activation selenoid to control the compressor.
I can remove the OEM 10 amp fuse and add a fused and switched line inside the cab. Really a no brainer until I thought about a wire size and my actual need to know. I have all sorts of wire, fuses, connectors and such but need a confirmation of wire size without going over board with a overly large size wire which will be a bit of a PITA to run throught the fire wall of the truck.
Hope this helps.

mole2 · 07-21-2014, 08:28 PM

How about this? Use the 18 gauge wire in conjunction with a under hood relay to control the solenoid. The 18 gauge wire is only being used to make/break ground for the coil in the relay and should be fine.

Water Warrior 2 · 07-22-2014, 01:32 AM

Quote:

Originally Posted by mole2

How about this? Use the 18 gauge wire in conjunction with a under hood relay to control the solenoid. The 18 gauge wire is only being used to make/break ground for the coil in the relay and should be fine.

That is basically what I want to do. The control solenoid has the same function as a relay. I just want to have a manual control of it. The solenoid/relay has a 10 amp fuse to energize it. What I want is to control the 10 amp line manually. The only reason I am asking if the 18 gauge wire will do is I happen to have a very nice molded 2 wire cord that is also the right length.

5th_bike · 07-22-2014, 11:23 PM

Aha, in that case you will only have to figure out the resistance of the solenoid coil.

if the solenoid's resistance is 6 ohms or larger, you're good with the 18 gauge. (From: The maximum sustained amperage through an 18 gauge wire is 2.3A. R = V / I = 12.8 / 2.3 = 5.56... ohms, round up for safety)

18 gauge wire can handle 16A but will run really hot then. And in that case (short circuit) the fuse will blow before your wire melts.

Water Warrior 2 · 07-23-2014, 01:22 AM

Quote:

Originally Posted by 5th_bike

Aha, in that case you will only have to figure out the resistance of the solenoid coil.

if the solenoid's resistance is 6 ohms or larger, you're good with the 18 gauge. (From: The maximum sustained amperage through an 18 gauge wire is 2.3A. R = V / I = 12.8 / 2.3 = 5.56... ohms, round up for safety)

18 gauge wire can handle 16A but will run really hot then. And in that case (short circuit) the fuse will blow before your wire melts.

So a 10 amp power draw will be safe enough then???

07-20-2014, 12:52 AM	#1
Water Warrior 2 Senior Member Join Date: Dec 2006 Location: Squamish B.C Canada Posts: 11,409	Alantf Got a simple question and need an answer from the best source I know. Is a 18 gauge wire adequate to run 10 amps a distance of 3 or 4 feet at 12 volts? Got a little project in mind for the Ford in my life. Login or Register to Remove Ads
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07-20-2014, 04:27 AM	#2
alantf Senior Member Join Date: Nov 2008 Location: Tenerife (Spain) Posts: 3,719	Sorry, but I don't know what 18 gauge is. This must be an American/Canadian terminology. In Europe we use the metric sizes (and have done for many years) 1.5mm² would be the minimum size for 10a (if not in continuous use), while 2.5mm² would be good for up to 32a. Just as a guess - America uses 120 volts, as opposed to Europe's 240 volts, and England's domestic lighting circuits are 5a. That means that American lighting circuits are 10a (W=VxA). So, if you find out what gauge the Americans use for domestic lighting, that should be ok for you. __________________ By birth an Englishman, by the grace of God a Yorkshireman.
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07-20-2014, 03:24 PM	#3
mole2 Senior Member Join Date: Dec 2009 Location: Longs, SC Posts: 1,469	In the US we breaker/fuse 14 gauge wire at 15 amps for 120v. This chart is for 12v. __________________ 2009 V-Star 650 Silverado Pearl White 2007 Suzuki GZ250 Black (sold) Login or Register to Remove Ads Last edited by mole2; 07-20-2014 at 03:29 PM.
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07-20-2014, 06:52 PM	#5
5th_bike Senior Member Join Date: Oct 2007 Location: HoCo, Maryland Posts: 1,349	Well 18 gauge can handle it (max 16A for a bare wire with sufficient cooling), but (assuming a total of 2 meter of wire, 1 meter each way) you will loose more than 0.1 V per wire, >0.2V total. The wire will warm up a bit, with 1W of heat dissipating. 18 gauge is not recommended to sustain a 5A supply of power, only 2.3A. If you want to stay with it for safety, by all means use the 18 gauge. Do wear safety glasses and have a fire extinguisher ready. For 5A it's safer to use 14 gauge or larger. Or, double up on the 18 gauge, then you should be OK. __________________ 2005 "Saturn Black", stock + tach Login or Register to Remove Ads
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07-21-2014, 08:28 PM	#7
mole2 Senior Member Join Date: Dec 2009 Location: Longs, SC Posts: 1,469	How about this? Use the 18 gauge wire in conjunction with a under hood relay to control the solenoid. The 18 gauge wire is only being used to make/break ground for the coil in the relay and should be fine. __________________ 2009 V-Star 650 Silverado Pearl White 2007 Suzuki GZ250 Black (sold)
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07-20-2014, 05:43 PM	#4
raul10141964 Senior Member Join Date: Apr 2012 Location: Elkhart, Indiana Posts: 369	12 gauge for 120V 20A outlet
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07-20-2014, 07:56 PM	#6
Water Warrior 2 Senior Member Join Date: Dec 2006 Location: Squamish B.C Canada Posts: 11,409	Oh my, I have opened up a can of worms. I will start over. I want to add a continuous draw system to my 12 volt Ford Ranger. Maximum of 10 amps. Here is the reason. Ford in their wisdom has no way to shut off the Air conditioner compressor and still retain all the air flow control. By switching the AC compresor off I can retain full control of all air flow positions. I want to add a switch to the AC activation selenoid to control the compressor. I can remove the OEM 10 amp fuse and add a fused and switched line inside the cab. Really a no brainer until I thought about a wire size and my actual need to know. I have all sorts of wire, fuses, connectors and such but need a confirmation of wire size without going over board with a overly large size wire which will be a bit of a PITA to run throught the fire wall of the truck. Hope this helps.
	0

07-22-2014, 11:23 PM	#9
5th_bike Senior Member Join Date: Oct 2007 Location: HoCo, Maryland Posts: 1,349	Aha, in that case you will only have to figure out the resistance of the solenoid coil. if the solenoid's resistance is 6 ohms or larger, you're good with the 18 gauge. (From: The maximum sustained amperage through an 18 gauge wire is 2.3A. R = V / I = 12.8 / 2.3 = 5.56... ohms, round up for safety) 18 gauge wire can handle 16A but will run really hot then. And in that case (short circuit) the fuse will blow before your wire melts. __________________ 2005 "Saturn Black", stock + tach
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