Can you put two wires in a crimp?

Steve T said:

Hi all,
Just wondering whether it is better to put two wires into one crimp or use two crimps with one wire in each?

The crimps in question here are ring crimps and the cable is flexible(fine stranded) 1.5mm2. If I put both of the wires into one crimp I would use the blue ring crimp but if one wire in each crimp I would of course use the red ones.
Thanks for any replies!

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I'd put them in individual crimps.
If you needed to separate the wires for testing (or any other reason) then you couldn't if they are in the same crimp.

Crimps or ferrules.
You can get double ferrules.

Paignton pete said:

Crimps or ferrules.
You can get double ferrules.

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Taking about crimps here. I've seen double ferrules so knew its OK to do for ferrules but wasn't sure if the same applies for crimps as they are somewhat different in structure

Steve T said:

Taking about crimps here. I've seen double ferrules so knew its OK to do for ferrules but wasn't sure if the same applies for crimps as they are somewhat different in structure

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Ppersonally I don’t see why you can’t put two in one. I never have, but I can see situations where it may make life easier.

Spoon said:

I'd put them in individual crimps.
If you needed to separate the wires for testing (or any other reason) then you couldn't if they are in the same crimp.

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What I'm doing is linking up 3 earth bars in a wiska box so I thought that putting two wires into one crimp would mean fewer connections so fewer failure points but that is really clutching at straws. I suppose it would be even better if I could remove sections of the wire insulation without cutting it at the points where the crimps need to be leaving the wire continuous throughout its length but I expect I may need a few attempts on flex?

Usually... a crimp connection is designed for a specific conductor size. I have no idea of exactly what you're trying to do from the brief details supplied, but I'd think very carefully before doing it.

The OP wants to crimp two conductors into one terminal, such that the total conductor area of the two is within the range suitable for the terminal.

If the ring terminals are of good quality, correctly crimped and securely screwed to the plate, the difference in reliability between two stacked rings and one ring with two cables should be trivial. But there are certainly situations (for me, not so much in installation work but within equipment) where it is helpful to crimp two into one and I sometimes do this in situations where a slight reduction in mechanical retention of the cable insulation (not conductor) would not be an issue.

Care is needed to ensure all strands of both cables go right to the end of the crimp tunnel; I like to strip them, cable tie them together with the ends of the insulation aligned so that they behave as one, and then trim the conductors to length. Depending on the type of terminal and insulation thickness, the entry funnel sometimes does not have room for the two cables side-by-side due to the extra layers of insulation. Obviously to make a satisfactory job the insulation must enter as far as possible, so it is sometimes necessary to form the entry into an oval first.

Actually last night (or this morning, I didn't finish Sunday's work until 2am Monday) I used a 25mm² copper tube butt crimp to connect six 4mm² stranded conductors to one 16mm² for some DC distribution in some mobile plant. Same deal, strap all six into a bundle with the insulation exactly level and the conductors over-length, gently form up the conductors together with a very slight twist, then trim to length and crimp. The 16mm² I stripped double-length, cut 10mm² of the strands to length and folded the rest back, to fill the terminal. Doubling a complete conductor back so that it loops through unbroken is nice in theory but difficult in practice, because the fold point bulges out at the sides and is larger than the sum of the two conductors.

In general, I would say care and skill are needed to ensure any non-standard deployment of crimps is sound. It is probably forbidden by the NEC (US wiring regs) where there is a specific requirement that only one conductor is placed in each terminal unless specifically designed for two.

IMO, two wires OK for stranded conductors but NOT for solid b

If space is extremely tight then ‘doubling up’ cables into a single crimp seems a logical solution.
you could keep the cable continuous and just peel back some insulation and feed the continuous loop into a single lug or crimp also

Steve T said:

I suppose it would be even better if I could remove sections of the wire insulation without cutting it at the points where the crimps need to be leaving the wire continuous throughout its length but I expect I may need a few attempts on flex?

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Thats possible with any of the automatic strippers that pull the sheath, just do it twice the distance apart you need and then cut the piece between the two, I have been using these to great effect: RS PRO, 450 V DIN Rail Connector, Screw Termination | RS Components - https://uk.rs-online.com/web/p/din-rail-terminal-blocks/3882861/ the end connector allows the rail to slide out and the continuous earth cable to be inserted, then the bonding cables suitably ferruled into the other terminals.

I use this type to pull the sheathing apart, they seem to be the best type as the cable can pass through the handle and strip mid length: CCS12 Cable Stripper 0.75mm - 16mm² - https://www.cablecraft.co.uk/ccs12-cable-stripper-0-75mm-16mm

I managed to strip sections out of a continuous piece of wire with a knife without nicking any strands, and doubled those stripped bits over to fit into a crimp. Crimped it tight with my tool and seems like a good joint. Certainly gave me a bit more space to work with inside the wiska box.
Unfortunately you can't really see the crimps themselves but I'm sure you get the idea. Thanks guys

I would say that is fine I have put two 1.5mm wires into a 4mm bootlace crimp without a problem pretwist them together and once the crimp is on it is a very tight fit without even being crimped, once crimped the connection is perfectly adequate in my view.

You can get dual-entry bootlace ferrules though, which are correctly sized e.g. a dual 1.5 is sized to take 3 sq mm copper in total, and has a suitably wide entry funnel. But there are no dual-entry insulated crimp terminals, which I think was part of what drew @Steve T 's attention.