OP
OtterBrookStables
Silver Member
No fuse panel - just a switch panel overhead. All fusing needs to be done individually.
HELP!! Wire size recommendations for 4120 cab power circuit
- Thread starter OtterBrookStables
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No fuse panel - just a switch panel overhead. All fusing needs to be done individually.
jenkinsph
Super Star Member
Otterbrookstables,
On my Laurin cab I have a fuse panel in the upper roof section with an access panel to dirstribute the power to the various loads. This makes for a short run to the switches for fan, wipers and lighting. You may wan't to check on getting a small 6 circuit fuse panel if you have a place to mount it, these are available with a weatherproof cover. Makes for a neat installation as well as adding some organization to the wiring.
I agree with proper bonding of the cab and frame to get good contact for your ground path, this is just as important as the positive lead.
I see no advantage to running two circuits instead of one larger curcuit to your distribution point. If you needed more power you could go with a 6 ga lead, but the problem would be that your alternator couldn't keep up if that were the case.
I keep mentioning the boating stores because they are a good source of weather resistant wiring materials including relays, circuit breakers, terminals and timmed wire. The conditions a tractor operates under with snow and rain and chemicals would be well served with marine grade wiring components.
On my Laurin cab I have a fuse panel in the upper roof section with an access panel to dirstribute the power to the various loads. This makes for a short run to the switches for fan, wipers and lighting. You may wan't to check on getting a small 6 circuit fuse panel if you have a place to mount it, these are available with a weatherproof cover. Makes for a neat installation as well as adding some organization to the wiring.
I agree with proper bonding of the cab and frame to get good contact for your ground path, this is just as important as the positive lead.
I see no advantage to running two circuits instead of one larger curcuit to your distribution point. If you needed more power you could go with a 6 ga lead, but the problem would be that your alternator couldn't keep up if that were the case.
I keep mentioning the boating stores because they are a good source of weather resistant wiring materials including relays, circuit breakers, terminals and timmed wire. The conditions a tractor operates under with snow and rain and chemicals would be well served with marine grade wiring components.
atschirner
Silver Member
Great suggestions Steve,
My original thought about two #10 wires was the availability of connectors and ease of working with a smaller gauge wire. I don't think that the 0.25" quick terminals on a relay would stand much weight or vibration from a #8 wire. To that same end, three #14 feeds would achive the same result. A hank of 14-3 SO cord might just be the hot ticket!
I'll be watching this post for the final update.
Have a safe Holiday, Alan
My original thought about two #10 wires was the availability of connectors and ease of working with a smaller gauge wire. I don't think that the 0.25" quick terminals on a relay would stand much weight or vibration from a #8 wire. To that same end, three #14 feeds would achive the same result. A hank of 14-3 SO cord might just be the hot ticket!
I'll be watching this post for the final update.
Have a safe Holiday, Alan
jenkinsph
Super Star Member
Alan,
Boating in a heavy chop can be just as problematic for wiring as running a tractor across rough ground. The sites and storefronts I mentioned have high strand count flexible tinned copper wire with acid and chemical resistant jackets. Using this type of 8 ga or 6 ga wire should not be a problem, and these sites have heat shrink type connectors too. Maine should have a reasdy supply of this stuff, just need to know where to look.
For the record in my business I use all SO and mining rated cords they are much better than whatever is in second place.
Boating in a heavy chop can be just as problematic for wiring as running a tractor across rough ground. The sites and storefronts I mentioned have high strand count flexible tinned copper wire with acid and chemical resistant jackets. Using this type of 8 ga or 6 ga wire should not be a problem, and these sites have heat shrink type connectors too. Maine should have a reasdy supply of this stuff, just need to know where to look.
For the record in my business I use all SO and mining rated cords they are much better than whatever is in second place.
atschirner
Silver Member
Steve,
I totally agree with your suggestion of marine grade cables and connectors for all the reasons you mentioned. My thought was only toward the leverage that a wire as large as #8 would apply to a quick connect flag terminal. If we were discussing a solenoid style relay with threaded studs I could see #8 living a long and happy life. On a Bosch style 40 amp cube relay I'd be concerned about maintaining a low resistance connection for any length of time. I looked around Google and only found one 8 ga. .25 quick connect connector and it requires a "U" type crimp tool.
Painless Wiring has some really nice switch and fuse blocks but they are a tad on the pricey side.
I can't wait to hear what the final set up is.
Best regards, Alan
I totally agree with your suggestion of marine grade cables and connectors for all the reasons you mentioned. My thought was only toward the leverage that a wire as large as #8 would apply to a quick connect flag terminal. If we were discussing a solenoid style relay with threaded studs I could see #8 living a long and happy life. On a Bosch style 40 amp cube relay I'd be concerned about maintaining a low resistance connection for any length of time. I looked around Google and only found one 8 ga. .25 quick connect connector and it requires a "U" type crimp tool.
Painless Wiring has some really nice switch and fuse blocks but they are a tad on the pricey side.
I can't wait to hear what the final set up is.
Best regards, Alan
jenkinsph
Super Star Member
Alan
For the record Otterbrookstables said he needed butt, ring and spade terminals to make it work.
For the record Otterbrookstables said he needed butt, ring and spade terminals to make it work.
OP
OtterBrookStables
Silver Member
Painless makes nice stuff, but it is expensive. The cube type of relay is commonly used in even higher current applications in cars and boats. The spade terminals lock in there pretty good - particularly if you just push them on and leave them. If you take the connector on and off frequently, they will loosen up some. I'll be sure to post some pics as the job progresses. Thanks for your inputs.
OP
OtterBrookStables
Silver Member
Here's an interesting factoid: I researched the Painless products and found that their 3-circuit, 40A kit has a 12 AWG main power wire. Their 40A, 7 circuit kit has a 10 AWG main power wire. I called Painless and spoke with one of their engineers - he says 10 gauge standed copper wire is more than enough for 40A, and is routinely used for 60A+ in 12VDC systems. They sell these kits by the thousands, so one would think that they must be engineered properly. Hmmmmmm........?
eepete
Platinum Member
Take a look at this site:
American wire gauge - Wikipedia, the free encyclopedia
Here's a hand waving argument on why all this is confusing. When you run current through a wire, it heats up. How much depends on the amount of current and the size (gauge) of the wire. The wire then has to get rid of this heat. The more it can get rid of, the cooler it is. If it is in the open air, like power lines that run down the street with no insulation on them and on glass insulators, the wire can get rid of a lot of heat and everything touching the wire can handle a lot of heat.
If the wire is in a bundle of wires, and that is near the top of the insulation in your attic on a hot sumer day, it's harder to get rid of the heat and you have insulation and other things touching the wire.
Things touching the wire means more than insulation. Connection points such as switches, plugs, outlets and disconnects, have a temperature rating on them just like insulation does. A popular disconnect is the Square-D disconnect which has a temperature rating of 75 degrees on it. Now look at the AWG table entry at that web site.
Note that the next to last column has ampacity with three different temperature ranges on it. Note that the "standard" amp capacity of wire as you would use in a household situation often corresponds to the 60 degree Centigrade value (140 degrees F). Those "standard values" (i.e. 12 gauge=20 amps, 10 gauge = 30 amps and 8 gauge = 40 amps) combined with minimum temperature ratings of 60 degrees C on most things you buy to wire a house let you connect things up without thinking (too much).
My 10 KW resistive electric heaters on my heat pump use a #6 wire with a 60 amp breaker. This works because the disconnects, breakers, and termination points in the heat pump have a 75 degree C rating (167 F). Note that the box stores will say that a #6 is good for 55 amps because they have to play it safe because we graduate 10 times more lawyers than engineers in this country.
More googleing of wire size ampacity will bring of lots of conflicting charts, all because they are running on different sets of assumptions. One fun one I saw was one that has the "fusing current" for a #10 at over 300 amps. If you've seen MAP gas used to braze copper, you know that's a pretty useless statistic because copper that hot would start a fire well before it melted.
From another table I have: 14 gauge wire, used with 15 amps circuits in the home, has an open air rating of 32 amps and a bundled rating of 17 amps.
In addition to the wire gauge, there are factors such as the insulation temperature rating, temperature rating for all devices connecting to the wire, the ambient temperatures the wire will see and how easy is it to get rid of the heat (bare wire, insulated, bundled, bundled and in an attic) that must be considered. Making matters more fun is the fact that the resistance of copper wire rises with temperature, aggravating the situation a bit.
So 40 amps on a #10 could work if the insulation was the right rating, the connections to it were the right rating (not hard with a ring connector crimped or soldered correctly), it was not buried in a wiring harness, didn't get run over the top of the engine, etc. There may be other information such as the fact that the actual draw on the connection is less than 40A except during brief periods where motors spin up and incandescent lighting turns on.
So there is the hand waving argument. I just want to create awareness of the factors in play here and hope the real electricians in the crowd won't toast me (and I don't mean with a beverage). For me, when I wire stuff, I use the household AC current ratings (as in 30 amps on a 10 gauge) and use 105 degree C 600V insulation stranded wire or SO cable if below 10 gauge. I like the 600V insulation for both it's higher rating and it's bigger size which is better mechanical protection. It really sucks when your wiring harness protects your fuse. A few bucks more and the fuses and everything works as it should without setting the tractor on fire. If it's a closed system where I have full control of everything, I do the math as I suspect Painless has done too.
Pete
American wire gauge - Wikipedia, the free encyclopedia
Here's a hand waving argument on why all this is confusing. When you run current through a wire, it heats up. How much depends on the amount of current and the size (gauge) of the wire. The wire then has to get rid of this heat. The more it can get rid of, the cooler it is. If it is in the open air, like power lines that run down the street with no insulation on them and on glass insulators, the wire can get rid of a lot of heat and everything touching the wire can handle a lot of heat.
If the wire is in a bundle of wires, and that is near the top of the insulation in your attic on a hot sumer day, it's harder to get rid of the heat and you have insulation and other things touching the wire.
Things touching the wire means more than insulation. Connection points such as switches, plugs, outlets and disconnects, have a temperature rating on them just like insulation does. A popular disconnect is the Square-D disconnect which has a temperature rating of 75 degrees on it. Now look at the AWG table entry at that web site.
Note that the next to last column has ampacity with three different temperature ranges on it. Note that the "standard" amp capacity of wire as you would use in a household situation often corresponds to the 60 degree Centigrade value (140 degrees F). Those "standard values" (i.e. 12 gauge=20 amps, 10 gauge = 30 amps and 8 gauge = 40 amps) combined with minimum temperature ratings of 60 degrees C on most things you buy to wire a house let you connect things up without thinking (too much).
My 10 KW resistive electric heaters on my heat pump use a #6 wire with a 60 amp breaker. This works because the disconnects, breakers, and termination points in the heat pump have a 75 degree C rating (167 F). Note that the box stores will say that a #6 is good for 55 amps because they have to play it safe because we graduate 10 times more lawyers than engineers in this country.
More googleing of wire size ampacity will bring of lots of conflicting charts, all because they are running on different sets of assumptions. One fun one I saw was one that has the "fusing current" for a #10 at over 300 amps. If you've seen MAP gas used to braze copper, you know that's a pretty useless statistic because copper that hot would start a fire well before it melted.
From another table I have: 14 gauge wire, used with 15 amps circuits in the home, has an open air rating of 32 amps and a bundled rating of 17 amps.
In addition to the wire gauge, there are factors such as the insulation temperature rating, temperature rating for all devices connecting to the wire, the ambient temperatures the wire will see and how easy is it to get rid of the heat (bare wire, insulated, bundled, bundled and in an attic) that must be considered. Making matters more fun is the fact that the resistance of copper wire rises with temperature, aggravating the situation a bit.
So 40 amps on a #10 could work if the insulation was the right rating, the connections to it were the right rating (not hard with a ring connector crimped or soldered correctly), it was not buried in a wiring harness, didn't get run over the top of the engine, etc. There may be other information such as the fact that the actual draw on the connection is less than 40A except during brief periods where motors spin up and incandescent lighting turns on.
So there is the hand waving argument. I just want to create awareness of the factors in play here and hope the real electricians in the crowd won't toast me (and I don't mean with a beverage). For me, when I wire stuff, I use the household AC current ratings (as in 30 amps on a 10 gauge) and use 105 degree C 600V insulation stranded wire or SO cable if below 10 gauge. I like the 600V insulation for both it's higher rating and it's bigger size which is better mechanical protection. It really sucks when your wiring harness protects your fuse. A few bucks more and the fuses and everything works as it should without setting the tractor on fire. If it's a closed system where I have full control of everything, I do the math as I suspect Painless has done too.
Pete
Last edited:
jenkinsph
Super Star Member
Nice detailed write up there Pete.
Now being an idiot and knowing nothing about electricity I am still befuzzled by the comment on page 1 about two circuits being more efficient than one. What do you think?
Now being an idiot and knowing nothing about electricity I am still befuzzled by the comment on page 1 about two circuits being more efficient than one. What do you think?
