Tinning or no...standard

[CEDEng]

Thanks all in advance...

Spirited debate here about panel wiring, with regards to securing conductors in terminal blocks, relay sockets, PLC I/O and the like.

Stranded wire (say, 18AWG for this discussion) - do you TIN or NO TIN the end of the wire?

(I'm of the NEVER TIN school, with some exceptions.)

There will be opinions aplenty on this - but is there a "standard" somewhere I can point at?

 

[petersonra]

Thanks all in advance...

Spirited debate here about panel wiring, with regards to securing conductors in terminal blocks, relay sockets, PLC I/O and the like.

Stranded wire (say, 18AWG for this discussion) - do you TIN or NO TIN the end of the wire?

(I'm of the NEVER TIN school, with some exceptions.)

There will be opinions aplenty on this - but is there a "standard" somewhere I can point at?

does anyone actually tin wires anymore?

IMO, it is a waste of time for normal wiring.

However, some form of wire protection needs to be in place for abnormal wires. I would consider anything that is smaller than #18 or finer stranded than class C stranding to be a good candidate for a ferrule or alternatively tinning.

 

[growler]

does anyone actually tin wires anymore?

Many of the conductors that are provided with equipment come from the manufacturer pre-tinned.

Crimp type connections are easier and better for field use.

 

[Little Bill]

When I worked in a plant, I had to tin wires all the time on machinery and in control panels.

They had small terminal holes that were a spring clip type device. The wires were anywhere from 16 ga to 26 ga finely stranded.

The holes were so small that it was hard to get the wires in without tinning. Sometimes you could twist them enough to get them in but I found that from the movement of the wires they were easily broken or pulled out. So the tinning not only allowed me to get the wires in the connector easier, but helped a lot to keep the wires from breaking/pulling out.

 

[mivey]

No tin. If I tin, then I'm gonna be soldering.

I use crimp terminals if under a screw like in a control panel, but not for a receptacle or switch.

 

[mivey]

When I worked in a plant, I had to tin wires all the time on machinery and in control panels.

They had small terminal holes that were a spring clip type device. The wires were anywhere from 16 ga to 26 ga finely stranded.

The holes were so small that it was hard to get the wires in without tinning. Sometimes you could twist them enough to get them in but I found that from the movement of the wires they were easily broken or pulled out. So the tinning not only allowed me to get the wires in the connector easier, but helped a lot to keep the wires from breaking/pulling out.

I could buy that. The little wire I recall in recent history went into a terminal block with screws so I did not have to tin but I did double the wire (isolation relay).

 

[CEDEng]

All good answers...thanks so far...

Tiny wires are one of my exceptions (just the tip). Press/hold terminals may be another.

There's plenty of reading that said the tinned end will compress and later loosen the connection, which is a good reason NOT to tin.

What I'm looking for, though, is a definitive answer - it can't be BEST both ways. One conductor into an IDEC relay socket? What about two in the same screw? How bout into a generic terminal block? And so on.

I've got two old-school guys here fighting it out, both swear their way is right. I'm sure there's only ONE way to do it at NASA, or the USAF, or....

 

[growler]

What I'm looking for, though, is a definitive answer - it can't be BEST both ways.

I've got two old-school guys here fighting it out, both swear their way is right.

Been doing it that way for 40 years and never had any problems.

I don't think there is and allaround right way. Different situations may call for different methods.

If I do a job for NASA I'll do whatever they spec. That's the right way for them.

 

[mivey]

Tiny wires are one of my exceptions (just the tip).

For the tiny holes (like the pencil-tip ones with a tapered entrance), you almost have to tin to overcome the spring pressure without collapsing the wire.

There's plenty of reading that said the tinned end will compress and later loosen the connection, which is a good reason NOT to tin.

Maybe for a loose screw connection but a good torque should be fine.

What I'm looking for, though, is a definitive answer - it can't be BEST both ways. One conductor into an IDEC relay socket? What about two in the same screw? How bout into a generic terminal block? And so on.

For an open terminal where you insert then screw down: No tinning needed.

For a push-in with tiny wire: probably was meant for solid or tinned stranded anyway so you would almost have to tin. Like the Greenlite GPC-254 that is for "22-12 AWG Solid or tinned stranded"

For bigger push-ins, the wire is stiff enough to not need tinning (the Wago 773 can handle #18 AWG with no tinning needed).

The Wago 222 lever nuts are not push-in but would not require tinning and can down to #28 AWG.

I've got two old-school guys here fighting it out, both swear their way is right. I'm sure there's only ONE way to do it at NASA, or the USAF, or....

Nope, there are two ways. Let them fight and you just do what works for you.

 

[spark master]

I just installed a garbage disposal. The white wire of the disposal was tinned, I couldn't get a good connection in a wire nut. I should of cut it off.

 

[Speedskater]

First we have two different 'tinning':

1] Tin plating of the individual strands of a stranded wire.

2] Solder tinning of the end of a stranded wire, effectively making it a solid wire.

You never want to solder tin the end of a wire under a screw terminal as with time and temperature changes the solder will cold flow and the screw will loosen.

You never want to solder tin the end of a wire that is subjected to high vibration as the end point of the solder will create a stiff spot that may fracture.

 

[CEDEng]

Thanks, all - that certainly brings the clarity!

I got at least one "NEVER..." in these responses. Maybe I should limit the question to a particular situation, like a screw-terminal on a relay-socket.

I really thought IDEC (to name one) would have THE way to do it. Maybe some time-tested studies or whatever. No luck so far.

But I sincerely appreciate the input from everyone!

 

[steve66]

My personal opinion is that solder is for soldered connections, and will only inhibit a good contact for a mechanical connection.

There is at least one paragraph in the NEC that prohibits solder for ground connections.

 

[Speedskater]

For stranded wire and screw terminals, think ferrules.

Ferrules - Wire Insulated Uninsulated Ferrule - Crimping Tools,
http://www.ferrulesdirect.com/