Splicing 12 AWG to 14 AWG question - help

[rvb]

Originally Posted by bibbs

If the inside skin is open you don't need to run the wires all the way back to there starting point. You can back feed from the nearest branch of the circuit. 15 amp or smaller fuse, you will be fine.

Spices in 120v wire should be in a box and accessible not enclosed in a wall etc. If you have not opened the walls use a surface mounted box in a location like under the bed or the back of a cabinet. Longer runs require larger wire. If you lengthen the circuit go ahead and use 12ga, just use a 15a breaker sized to the smallest wire in the circuit.

[TouringDan]

The OP said the wiring was for his 12v circuits so junction boxes are not required.

If everything was open I would probably consider running all new marine stranded wiring. I am sure #14 is fine but maybe even consider dropping to # 16 wire for all circuits except the furnace fan. I have converted to all LED interior lights and most are less than 1 amp. I do have two 40" light fixtures that use 3 amps each. By converting to LED lights the current required should be less than 15% of the incandescent light fixture requirement.

Make sure you add plenty of 12v outlets for powering/charging all your 12v electronics stuff. I just installed 7 outlets in my Tradewind.

Dan

[lewster]

Originally Posted by MelGoddard

Isn't 12 ga. max of 30 Amp?
My 30' FC is 30 Amp, with 12 ga. power cord.
( I would like to have 10 ga. cords to limit line loss over a longer run; but Jeez, they're heavy, and not readily available.)
14 ga. is max 20 amp, but fusing at 15 is very good.

All 30 amp shore cords should be a minimum of 10AWG. I'm sure yours is.

12AWG is commonly rated to 20 amps and 14AWG to 15 amps. These are MAXIMUM ratings and there are extensive tables to calculate how to 'de-rate' the ampacity of these wires (according to the ABYC) depending on the voltage applied, length of the run, number of wires contained in a run and a few other specifications.

[MelGoddard]

Originally Posted by lewster

All 30 amp shore cords should be a minimum of 10AWG. I'm sure yours is.

12AWG is commonly rated to 20 amps and 14AWG to 15 amps. These are MAXIMUM ratings and there are extensive tables to calculate how to 'de-rate' the ampacity of these wires (according to the ABYC) depending on the voltage applied, length of the run, number of wires contained in a run and a few other specifications.

Damn, you're right. I looked up some tables, and I'm gonna check out a short extension cable that I made. but not yet used.
I might have used the wrong ga. wire on it.

Raises a question though. What gauge would AS be using for 50 amp service? They have two separate circuits don't they?

[lewster]

Originally Posted by MelGoddard

Damn, you're right. I looked up some tables, and I'm gonna check out a short extension cable that I made. but not yet used.
I might have used the wrong ga. wire on it.

Raises a question though. What gauge would AS be using for 50 amp service? They have two separate circuits don't they?

It is 6AWG for the main conductors (2 hot leads and the neutral). They reduce the ground to 8AWG (which is allowed by NEC) but would also need to be 6AWG to follow ABYC specs.

All 50 amp shore cords also use 6AWG for the main conductors.

[Mollysdad]

Originally Posted by mayco

A 25 ft long, 30amp power cord "should be" #10 ga wire.

Yes, at 125 v.
The OP is talking about replacing the 12v. system and most here are quoting the specs for 125 v.

If I was doing it, and had the interior walls off, I'd replace all the interior wiring with new stranded, tinned, 14 or 12 ga. Either is fine. Tinned for corrosion resistance, stranded for vibration, and the fewest connections possible.

[batman]

Wow!
Perhaps I missed something. Here is what I read. The OP has changed the batteries and location. He wants to wire from the NEW 45 AMP converter to the NEW battery location and the NEW fuse panel.
We don't know the Amperage of the old converter (20 amps)? Nor do we know the distance from the old converter to the old battery location (15')??
The picture of the wire is a little vague, however it looks like 10awg to me. Given the guestimate I have given, 10awg would work for the old system.

We know the NEW converter is 45 amps and we know the distance is being increased, but not how far.
Lets say, it is just 5 feet. That would be 20 feet total from the converter to the batteries. 45 amps at 20 feet. That would equate to using 4awg wire.
Here is a quick reference guide. http://www.engineeringtoolbox.com/am...uge-d_730.html

It dose not matter what loads you are running off the fuse block, LED's, etc. that was not the question.

The OP also whats to "spice" additional wires to an existing light source.
Since the inside panels are off why not do it right. Run a power lead (I would run 10awg) from the new panel, to a screw type connection buss and from there run the other wire's (12 or 14 awg) to power what ever.

My best advice, do some home work.


-Dennis

[Silver Hawk]

MelGoddard:
"Isn't 12 ga. max of 30 Amp?" No!

featherbedder is right: 12 ga. is fused at 20 amp, 14 ga. at 15 amp.

at 30 amp your asking for overheating and fire before it blows!

Fuses are to protect the wiring. Not the appliances.

Check any electrical wiring manual.

[Scorge-ION]

Make a drawing! Dr. Stephas docked me points for not making a drawing even when I got the correct answer. My first professional job, my mentor told me to study the problem by making a drawing. It's still the best way to focus on the problem.
Original post was asking how to splice 12 AWG to 14 AWG.

Fuses and wire gauge are something else.
There are two separate issues with wire gauge:
1. keep the plastic insulation from melting (fuse it low enough to keep the wire from overheating)
2. prevent excess voltage (I*R) drop (you have more to play with using 120 Vac than with 14 Vdc. E.G., if you have a half-ohm wire and 20 amps going through it, you will have a ten volt drop. Ten volts - 120 down to 110 is significant but a ten-volt drop on a 12 volt circuit would leave you with only 2 volts!

Now, back to the OP.
Several ways to splice but the common crimp-on butt splice is underrated.
Common crimp-on butt splices: I've used them quite a bit but we don't have the corrosion problems in northern Nevada that you have. Clean the wires very well so fresh, bare copper is exposed. This is because the splice material fuses to the copper wire - they're essentially spot welds. This is good enough that it's the standard practice in the telecommunication industry where everything is expected to be operational 99.999% of the time. Similarly, the aviation industry has done careful statistical analysis of crimped vs. soldered connectors and found no difference in reliability. Military aviation thinks nothing of running silver-plated copper wires to reduce corrosion in crimped on connectors.
DO NOT put anti-seize lube on the wires before joining. Anti-seize will prevent the wire spot welds.
However, I've found it good to coat the joint with anti-size or Cosmoline AFTER joining. (Actually, I use Sanchem No-Ox-Id A Special. Cosmoline brand is too expensive and not as handy.)
Then put a good tacky-inside shrink tube over it.
Yes, I've used everything from Western Union splices to insulation displacement connectors on low voltage connections. This works as well or better in every situation except where there's tension on the splice; and there, think about removing the tension.
Best regards, Dave the Scourge of the ION

[crispyboy]

Here is a wire splice procedure from the automotive industry that I have successfully used.

Attachment 280236

Also there are some crimp connectors available at Fastenal, a good hardware store, etc....with the heat shrink already on them. Just crimp the wires and seal with a heat gun. Very easy to use and I carry some in the trailer emergency tool box. I have used these on brake wiring with success.

https://www.fastenal.com/products/el...10%20AWG%22$|~

[garry]

Assuming you have the new converter and fuse panel as "close" to the batteries as possible I would say you are OK using max 15 amp fuses at the new 12V fuse panel.

Wire from the converter/batteries to new 12v fuse panel should be sized by distance at 45 amps. Up to 3 ft I would use 6 gauge with a 40amp slow blow fuse or 40 amp ckt breaker.

[MelGoddard]

Originally Posted by lewster

It is 6AWG for the main conductors (2 hot leads and the neutral). They reduce the ground to 8AWG (which is allowed by NEC) but would also need to be 6AWG to follow ABYC specs.

All 50 amp shore cords also use 6AWG for the main conductors.

OK, Thanks for the info. BTW; I did check my homemade 'shortie', and it is 10 ga. so I'm OK there.

[waninae39]

go 12 GA the whole way, replace the old 14 GA
the losses on 12 GA are lower than 14GA.
under higher loads you will notice the difference.
if you use both , you are limited by the lowest cable ie 15 A with 14ga
go 12 GA and use a 20 fuse

[nocmanus]

Originally Posted by batman

Wow!
Perhaps I missed something. Here is what I read. The OP has changed the batteries and location. He wants to wire from the NEW 45 AMP converter to the NEW battery location and the NEW fuse panel.
We don't know the Amperage of the old converter (20 amps)? Nor do we know the distance from the old converter to the old battery location (15')??
The picture of the wire is a little vague, however it looks like 10awg to me. Given the guestimate I have given, 10awg would work for the old system.

We know the NEW converter is 45 amps and we know the distance is being increased, but not how far.
Lets say, it is just 5 feet. That would be 20 feet total from the converter to the batteries. 45 amps at 20 feet. That would equate to using 4awg wire.
Here is a quick reference guide. http://www.engineeringtoolbox.com/am...uge-d_730.html

It dose not matter what loads you are running off the fuse block, LED's, etc. that was not the question.

The OP also whats to "spice" additional wires to an existing light source.
Since the inside panels are off why not do it right. Run a power lead (I would run 10awg) from the new panel, to a screw type connection buss and from there run the other wire's (12 or 14 awg) to power what ever.

My best advice, do some home work.


-Dennis

There is NO old Converter. The old univolt system is out. Old original battery out. The wires hanging down (see pic) went into the old univolt system. My question was in regards to 12 volt wiring ONLY. Could I splice those 14 gauge wires at the current location with 12 gauge and run the 12 gauge into the NEW fuse box with a 15 amp fuse for each circuit.? 3 wires, 3 15 amp fuses. The reason, is because I have moved the location of where the batteries will be. The batteries will be in front, I needed a longer run if I wanted to splice. The new Converter will be next to the battery bank.

This Post really went wrong so fast. lol

[nocmanus]

Originally Posted by garry

Assuming you have the new converter and fuse panel as "close" to the batteries as possible I would say you are OK using max 15 amp fuses at the new 12V fuse panel.

Wire from the converter/batteries to new 12v fuse panel should be sized by distance at 45 amps. Up to 3 ft I would use 6 gauge with a 40amp slow blow fuse or 40 amp ckt breaker.

That is the plan. The new converter and fuse box will be within 3 feet from the battery bank. Thanks for the reply.