Getting three wires into one screw hole

vaio

Twisted or not doesn't really matter, what is critically important is that all conductors are firmly clamped at the connection point with a minimal amount of exposed copper

Twisting as described in # 19 is a recipe for disaster, twisting as described in #18 is fine and might even have advantages

prowla

muckybutt wrote: »

I didnt say they shouldnt be put in singularly ! that is how they should be.

As for twisting the wires takes up more room ? thats ridiculous ! the wires dont grow thicker lol and the individual wires will still be the same cross sectional area.

This is one reason part p was bought in dodgy diyers thinking they are sparkies.
Follow my or dsvardy's advice.

If you look end-on at 3 straight wires, then they will have 3 wider points and 3 grooves; if you look at 3 wires twisted end-on, then they will appear as a circle of diameter corresponding to the widest point. In other words the area viewed end-on of twisted wires is larger than 3 straight ones.

Also, since the 3 straight ones are not held together they may be coaxed to fit into an oblong hole differently, whereas 3 twisted ones won't. So obviously whether the hole is circular or oblong makes a difference.

You need to be able to understand a bit of mathematics and to visualize shapes to understand that sort of thing.

DVardysShadow

vaio wrote: »

Twisted or not doesn't really matter, what is critically important is that all conductors are firmly clamped at the connection point with a minimal amount of exposed copper

Twisting as described in # 19 is a recipe for disaster, twisting as described in #18 is fine and might even have advantages

A real corkscrew of a twist stresses the metal and you can expect it to fracture if the fitting is opened up more than once or twice. A gentle twist is OK.

One of the properties of copper is that it hardens as you work it. It comes off the reel 'annealed' - ie in a soft state. A twist which work hardens it a bit means that the copper does not retreat from the clamping screw over the first day or so, because of a small degree of work hardening. Working it with a corkscrew twsit means that you have very hard copper next to ve'y soft copper an no graduation in hardness. It tends to break at the first soft copper adjacent to the work hardened copper.

ed110220

diable wrote: »

5 years of a City and Guilds 236 Part 1 and Part 2 wasted, I should have come on here and did a distance learning course.

How many 2.5 mm cables allowed in to a 25 mm metal conduit located in an aviation fuel depot?

Half as many as the number of jackhammers allowed to be tested in a nitroglycerine store

Seriously though, thanks for the advice and no I won't twist them.

DevCoder

The wrapping wires around the lower part of one wire and then inserting the single wire into the connector is dangerous beyond belief.

Not only is there arcing/shock hazards but also you are now asking the CSA of one core to take the current of the other two as well.

So instead of each 2.5mm² taking the current to the connector, potentially 13amps, you are asking one 2.5mm² core to take potentially 39amps.

diable

ed110220 wrote: »

Half as many as the number of jackhammers allowed to be tested in a nitroglycerine store

Seriously though, thanks for the advice and no I won't twist them.

I was taught to twist them together, oh well what a wasted education.......

keystone

krisdorey wrote: »

The wrapping wires around the lower part of one wire and then inserting the single wire into the connector is dangerous beyond belief.

The perp of this absurd piece of unsafe bodgery appears to have got the message and has retired with tail well and firmly between their legs some time ago.

Cheers.

waynehayes

For what it's worth, I was taught never to twist cables togeter. One of the main reasons: If the CPC's on a ring final have been twisted together, then for some reason come away from the terminal, you will still get an end to end reading, but no earth connection at the socket. Of course, other tests should pick up the problem, so long as testing is being carried out at each socket.

DevCoder

Agreed, likewise if one of the other conductors becomes disconnected then youd end up with two radial circuits as opposed to one ring final and as electricity takes the path of least resistance then flows exceeding 16amps could be sent down one radial which would exceed the regs.

pendragon_arther

red alert, condition red!

do not use this dangerous method. I tried it and now my house is burned down. 20 fire tenders attended the fire. Now i am homeless.