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Old 23-04-2012, 04:23   #16
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Re: Connection between mismatched wire sizes

Do you have a workable answer or do you want me to throw this to Capt Perfecto? Should be able to get you an answer by this evening unless you've got a plan already.
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Old 23-04-2012, 04:48   #17
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Re: Connection between mismatched wire sizes

Target here's your answer from the sparky himself.

Double your smallest wire over on itself to increase diameter. Butt splice, solder, one pass electrical tape then heat shrink.
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Old 23-04-2012, 05:48   #18
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Re: Connection between mismatched wire sizes

HUD, Gord, really? Those connectors are begging for some serious corrosion and weeping, especially with any mast connections.
capn bills #9 post seems to be the best solution so far. Using proper terminal blocks and ring connectors. That being said I DO NOT like suggesting splicing smaller wires to larger wires. Chances are very good (because I've seen this so many times) that the larger wire is the only one protected up to it's over current rating and the smaller wires always seem to be forgotten. These smaller wires can then carry the same current as the larger one it is spliced to. Very bad.
Think of it like the electrical panel in your house. If you wanted to add a sub panel you would not just run a larger cable from your main panel off of a say 50amp breaker to the sub panel then just splice all the 14/2 and 12/2 wire to the end of the sub feed. You add more breakers appropriate to the load.
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Old 23-04-2012, 06:02   #19
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Re: Connection between mismatched wire sizes

I was looking for a better connector.
Really like (not in the marine world) american wire nuts.
Saw those connectors look similar (but crimped). If heat shrunk properly should be ok??? To have the wires twisted together seems so much better than crimping separately in a typical but connector...

My take on a device (pump, light, fan) is that it has wire stubs that are rated to carry the correct amount of current for the device - from the manufacturer. The device must be correctly protected ( according to the manufacturer).
If mounted further away, the wire size is upped appropriately to avoid voltage drop over the run (there are tables for this). Current draw of the device remains the same and so does the circuit protector...
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Old 23-04-2012, 06:19   #20
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Re: Connection between mismatched wire sizes

If you google them you can find the in step down for just about any size.Adheasive heat and seal.Used them for years and am wondering why there not know/used here?
Butt Connectors-Step Down

This is just the first that came up when i googled them.Have bags of basically the same thing in wire bag.
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Old 23-04-2012, 10:24   #21
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Re: Connection between mismatched wire sizes

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Originally Posted by Target9000 View Post
This is very true, however... For instance the wire running up our mast is 10g and the old anchor light used/needed that big wire for such a long run. The new LED anchor light we got from Bebi is comically small in comparison. It seems nutty to rerun the mast wire.

I'm liking those crimp caps that Hud and Gord showed, never knew such a creature existed. I suppose if you crimped and then used adhesive heat shrink over it would hold up pretty well.
Wow, 10 GA up the mast. Mine is only 14Ga. For a mast top, I would use the crimp on nuts in the earlier post. You'll want to fold over the 22 Ga and make sure you get a good solid crimp on both wires. You also can selectively cut some of the 10 ga strands back a little to fit in a smaller crimp, (not at the same point or you'll get a weak spot), seal well however you do it. You most likely don't want to go up there again.
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Old 23-04-2012, 12:10   #22
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Re: Connection between mismatched wire sizes

A couple of people have mentioned it....the load should be protected. You also want to shut off devices...like the mast lights.

Batteries -> switch -> load center with main breaker (sized for 10GA wire) -> individual branch circuits (protected for load requirements; one of those runs up the mast on your 10GA, but may be low amp breaker for the load)

Up the mast, twist the wire ends together, ...

then use the described crimps with heat-shrink or dip in liquid electrical tape, ...alternatively, use self adhesive heat-shrink tube to cover the twisted wire ends. The idea is to keep the moisture out and the mechanical connection secure, so do what is necessary; such as orientation of the crimp connector so that it drains moisture instead of holding moisture.

The adhesive heat-shrink seals to itself and is durable. It's worth the extra $$ compared to the cheapest shrink tubing.

Use terminal blocks with ring terminals on wire ends inside the boat to connect the return path (negative connection). It is the most secure. ABYC is the standard. Also note that the current standard for 12VDC also says the conductors are colored red (pos) and yellow (neg), so there is no confusion with 120VAC conductor colors, black (hot) and white (neutral). So, if you're buying wire for 12VDC, buy red and yellow colored conductors if you have the choice. Good luck.
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Old 23-04-2012, 12:15   #23
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Re: Connection between mismatched wire sizes

Ok, here is the more detailed info I promised.

From the description it sounds like 10AWG wiring is being used as bus wiring to provide power to multiple consumers. This being the case, installing one or more fused distribution panels at strategic locations in the boat should be considered. At the fuse panel the correct fuse rating for the consumer and it’s wiring can be installed. The consumer wiring can then be terminated with ring crimps and soldered

The reason for adding fused distribution is:
i) The protection device supplying the 10AWG wire is likely to be significantly higher than the current carrying capacity of the small gauge wire mentioned. This being the case, if you connect directly the small gauge wire to the 10AWG you’ll have the following issues:
a. An overcurrent situation at the small gauge wire can result in overheating and fire risk,
b. If connecting multiple consumers to the 10AWG wire, a short circuit at an end device will cause a loss of supply to all devices. Fault finding in this scenario becomes more difficult
c. It is a code violation to have a protection device rated higher than the current capacity of the wire.
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Old 23-04-2012, 12:30   #24
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Re: Connection between mismatched wire sizes

Most people think the breaker is to protect the end equipment from catching fire, but that's not correct. The correct size breaker is to prevent the wire from overheating and causing a fire. Both Tellie and Mimsey are correct.
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Old 23-04-2012, 12:46   #25
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Re: Connection between mismatched wire sizes

As a side note, I know about correct breaker/fuse size for minimum wire in the circuit. Just ran into a situation with the mast where I really don't want to rewire it until we take it down but do want to install the LED lights since our old lights don't currently work.
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Old 23-04-2012, 12:52   #26
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Re: Connection between mismatched wire sizes

Just sail the boat to Houston and you and Capt. Perfecto can get all jiggy with the wiring while your good lady wife and I have margaritas.
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Old 23-04-2012, 12:54   #27
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Re: Connection between mismatched wire sizes

"Honey, can you pass me the crimper?"

"Sure baby, just as long as you can pass me back that bag of limes."
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Old 23-04-2012, 13:44   #28
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Re: Connection between mismatched wire sizes

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Originally Posted by Tellie View Post
HUD, Gord, really? Those connectors are begging for some serious corrosion and weeping, especially with any mast connections ...
Not really.
If using the Splice Cap Crimp Terminal c/w Splice Cap Insulators, I fill the cap with silicone, and heat shrink overall.
If the wire bundle isn’t very big (diameter) you might have to install a shrink over the wires first (prior to installing cap; to increase diameter so final o/all shrink will get a grip on both cap & wires).

Sometimes, I’d forgo the insulator cap, and just shrink (sometimes double) over the copper crimp sleeve, having filled the open end /w silicone.

The major downside of these crimps, is the need for (another) expensive crimper (Ideal/Buchanon #C24 @ ±$80).

Doubling (tripling) the smaller wire might be OK, if the smaller wire isn't "too" small".

Step-Down butt splices are great (& better than doubling), but generally only reduce a single wire gauge (or 2).
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Old 23-04-2012, 14:12   #29
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Re: Connection between mismatched wire sizes

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Most people think the breaker is to protect the end equipment from catching fire, but that's not correct. The correct size breaker is to prevent the wire from overheating and causing a fire. Both Tellie and Mimsey are correct.
This isn't technically correct , this is just a "custom and practice" thing, CBs can be used at much lower rates then the wire can carry. I use them instead of inline fuses, which I hate. I have wires capable of carrying 30amps, with 5amp Cbs protecting the equipment.


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Old 23-04-2012, 17:01   #30
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Re: Connection between mismatched wire sizes

In the OP's case, he just wants to fix a light on the top of the mast. I'm sure all the lights are on a single low amperage fuse. The 10 Ga isn't the problem, it's the 22ga to the LED which is probably milliamps.

Short of rewiring the mast, which he didn't want to do, his only option is to have a connection of some kind at the top. I recently had to do the same thing, but with a much smaller difference in wire sizes. I don't see any option but to have some kind of connection at the top of the mast, just make it a solid connection and seal it watertight. In a few years, (more if you did a good job sealing it), replace it.
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