Crimping t/y splice into 16mm2 cable

[towpathrider]

I am about to rewire my boats with 16mm2 cable that will feed a number of 12v sockets and a couple of wired in static/stationary 12v devices.

 

I plan to run one circuit and tee off smaller tails for the sockets, does anyone have any good suggestions as to how could crimp the cables together?

 

I don't want to have to cut the 16mm cable, so was thinking of getting butt crimps large enough to slide over the insulation, so that I can remove insulation in the places I want to put a socket, exposing enough wire to make a splice crimp.

 

I have a pair of hydraulic crimpers for this.

 

Does anyone have a better idea?

[John V]

Been thinking about this one. Presumably you will be using fairly thick tails for the Tee (or doubling the end where it goes in the crimp).

I can't see any flaws in it......it should be pretty good mechanically and electrically.......have you given thought to insulating ?

Possibly those small snap over covers full of "magic gell" might be better than taping up even using self amalgamating. and would mean you could access the joint easily if you needed to.

The only alternatives I can think of that don't cut and join the main feed are those "double clamps" that are used in some of the armoured cable underground joints but they are physically much bulkier and to be honest they are not a connecter I have ever been keen on.

 

 

edit for spelnig and phat phingers

Edited April 12, 2016 by John V

[MtB]

I think the awkwardness and practical difficulty in doing this is the reason it is not normal practice to wire power sockets (of any voltage) in this manner.

 

Simpler and more easily altered if necessary at a later date to run some fat wires to a pair of bus bars at the front of the boat, then run individual pairs of cables to each power outlet ('star' format).

[John V]

I suppose it comes down to how sure your installation is not going to require modification.......a very hard thing to predict.

If the OP wishes to do it this way I can think of no reason not to from a purely technical perspective

[RLWP]

The only thing I can think of is the danger of damaging the cable while trying to remove the insulation

 

I wouldn't do it like this

 

Richard

[Tony Brooks]

Remember that if you use thinner cable for any spur then it must have its own fuse so you end up with fuses scattered throughout the boat. If this idea appeals then I would suggest that you use Mikes idea but maybe feed three local distribution/fuse/mcb boxes. One at each end and one in the middle. That way you get the fusing you need, easily identified points for fault finding and easy connections for the smaller cables.

[John V]

 

Remember that if you use thinner cable for any spur then it must have its own fuse so you end up with fuses scattered throughout the boat. If this idea appeals then I would suggest that you use Mikes idea but maybe feed three local distribution/fuse/mcb boxes. One at each end and one in the middle. That way you get the fusing you need, easily identified points for fault finding and easy connections for the smaller cables.

 

 

I would take issue with that as a categorical statement.

 

Often the cable dimension on a 12v circuit are way in excess of the fused ratings as often it is determined by the permissible volt drop as opposed to the current carrying capacity. As long as the carrying capacity of the spurs is in excess of the main fuse this is not the case

Edited April 12, 2016 by John V

[Split Pin]

These used to be commonly used in industrial installations on 3 phase circuits, normally in an insulated box http://www.cablecraft.co.uk/line-taps-for-branch-joints-10mm.html

 

Any good industrial electrical wholesalers should have them.

 

Steve

Edited April 12, 2016 by Split Pin

[ditchcrawler]

These used to be commonly used in industrial installations on 3 phase circuits, normally in an insulated box http://www.cablecraft.co.uk/line-taps-for-branch-joints-10mm.html

 

Any good industrial electrical wholesalers should have them.

 

Steve

Long time since I used one of them, so much so I had forgotten until I followed your link. OK up in the air but a bit bulky if you plan on 6 pairs down the side of the cabin.

[John V]

These used to be commonly used in industrial installations on 3 phase circuits, normally in an insulated box http://www.cablecraft.co.uk/line-taps-for-branch-joints-10mm.html

 

Any good industrial electrical wholesalers should have them.

 

Steve

 

Blimey, I'd forgotten those.........I think I have only seen them once and that was a loooooong time ago

[Guest]

Long time since I used one of them, so much so I had forgotten until I followed your link. OK up in the air but a bit bulky if you plan on 6 pairs down the side of the cabin.

They are similar idea to what were called "line taps" as used by the Leccy Board that I once worked for. They do the job but are clumsy (the leccy board type) and would have to go in an insulated box in a boat environment.

I had once thought of wiring our boat thus but quickly changed my mind.

I will be skinned alive for saying this on here, and wouldn't recommend it on a boat, but the neatest way of spurring a small cable from a large one is to do a "married joint" with solder (never used one in the real world and only ever did one as an apprentice!)

Edited to avoid confusion.

Edited April 12, 2016 by Guest

[ditchcrawler]

"married joint" with solder (never used one in the real world and only ever did one as an apprentice!)

Same here, but I think its against the BSS rules a soldered joint

[GUMPY]

Any crimp large enough to pass over the insulation will not crimp down far enough to make a decent joint.

Personally I wouldn't do it this way but if you must:

Cut the cable where you want the spur and use 16mm through ferrules insulated with heatshrink. You can get at least one bit of 2.5 in the ferrule as well as a bit of 16mm so creating the spur.

 

Remember it must be fused to allow for the thinest cable in the circuit......

Edited April 12, 2016 by Loddon

[Guest]

Same here, but I think its against the BSS rules a soldered joint

Soldering is not ideal really for a few reasons. Much better some kind of crimp or mechanical method on't boat.

[MtB]

Same here, but I think its against the BSS rules a soldered joint

 

 

Really? Can you (or anyone) cite the rule please?

 

Thanks.

[RLWP]

Any crimp large enough to pass over the insulation will not crimp down far enough to make a decent joint.

 

Well spotted

 

Richard

[GUMPY]

Just tried and the smallest crimp that will go over 16mm cable is 50mm, case rested m'lud

[Guest]

Just tried and the smallest crimp that will go over 16mm cable is 50mm, case rested m'lud

Agree a crimp wont do without cutting the main cable. The only ways I can think (without cutting main cable) solder (not ideal) or a clamping device as per another post (likely better than soldering but not as sound as a crimp.)

For these reasons I abandoned the idea of using this method of wiring my boat.

[John V]

Just tried and the smallest crimp that will go over 16mm cable is 50mm, case rested m'lud

 

 

Hmmmmm.......not so sure........a 50mm crimp slips easily over the insulation of a 25mm tri-rate. I don't have any 16mm tri-rate on board to check but I would have thought a 35mm would go over it

[towpathrider]

Thanks for all the replies, i think i will go with my method, the reason for using large wire, and wanting to t off as close to the socket/appliance as possible is just voltage drop/efficiency in a 60ft narrow where the living area is the opposite end to the batts.

 

The wiring will be concealed, but accessible under the gunwhales, so i will make sure to slide on extra crimps and heat shrink in case i need to add or alter.

 

The wire I have is the thick stranded type, this means i can easily remove the insulation with a craft knife without cutting through any of the strands.

 

If i were to use the spider method some of the legs would have to be pdetty long, which would negate the large wire in the first place, unless i replaced it with much larger cable.

 

The main worry i had is with the strength of the crimp, but i will be using 6mm2 for the tails so hopefully will be ok.

 

Is there such a thing as an "open" butt splice crimp that i coukd put on without havjng to silde it over the wire?

[BMC problems]

They are similar idea to what were called "line taps" as used by the Leccy Board that I once worked for. They do the job but are clumsy and would have to go in an insulated box in a boat environment.

I had once thought of wiring our boat thus but quickly changed my mind.

I will be skinned alive for saying this on here, and wouldn't recommend it on a boat, but the neatest way of spurring a small cable from a large one is to do a "married joint" with solder (never used one in the real world and only ever did one as an apprentice!)

 

Clumsy? How so? in a box they look like a fairly neat solution - do you use rings once the tap is bolted tight?

The main argument would seem to be one of cost, at £10 the pair for 16mm

 

I think rings to a bus bar in an IP65 box at 4 or 5 locations is the way to go. Then have a fuse in each box, a clever solution would be an LED bridging each fuse so if it blew the LED would light although fault finding is not complicated - "the saloon lights are out, it's probably the saloon junction box fuse" not beyond the wit of man.

[towpathrider]

Just missed the last few replies re. Crimp size - i havent been able to test but the wire i have has quite thin insulation, much thinner than the thick stuff that is usually found on multi strand cable of that size. The cable is actually a 50m drum of earth wire that i got a good price on.

 

I was hoping to fit over a 25mm crimp, but havent been able to test. I know that isnt ideal, but the hydraulic crimper does quite a good job of squishing. . .

[BMC problems]

I could start an argument now by making the statement "voltage drop is not as important as it's made out to be"

[towpathrider]

And yes, planning to fuse everything.

If anyone has a measurement for the inside diameter of a 25mm crimp thay would be super useful!

If anyone has a measurement for the inside diameter of a 25mm crimp thay would be super useful!

[towpathrider]

These used to be commonly used in industrial installations on 3 phase circuits, normally in an insulated box http://www.cablecraft.co.uk/line-taps-for-branch-joints-10mm.html

 

Any good industrial electrical wholesalers should have them.

 

Steve

I like the look of these - would solve a few issues. If i fit them side by side - slightly offset, woukd there be space under a 6-7 cm gunwhale?

 

Only problem then would be insulating them.

Edited April 12, 2016 by towpathrider