Three phase switch on single phase.

[Maker]

Is it safe?
I've got this big three phase switch;

And I want to use it to switch the mill's single phase motor on and off. Is it safe/acceptable to wire it with only one live? Obviously neutral can go through the neutral connection but I don't want to break it by only giving it one live.

 

[brightspark]

its ok to use if the contacts are rated to the motor current draw

 

[Maker]

Okay, thanks.
Is T1,2,3 or L1,2,3 the supply? Or does it not matter?

 

[Paulbarrett]

L1/2/3 supply side,
Can use that fine with single phase, id assume its rated at 16a looking at size of it but it should say in it somewhere

 

[Maker]

Well this is embarrassing, there's a little sticker with the ratings for both single and three phase In my defence, the sticker is very small and upside down. It's good for 1.5HP on 240V which is plenty. I'll make a bracket and get it all wired in in the morning.

 

[Maker]

Whatever you do do don't do what I saw someone else did do

I picked up a motor at a boot sale which had a switch unit and a plug fitted, seller was all "it's ready to go, I wired it all up fine" - yeah, ok, it was cheap enough, soooooo...

He'd used a 3 phase switch and put live to L1, neutral to L2 and EARTH to L3.

Do not switch your earth!

Don't worry, I'm not stupid. There's an earth connection next to my thumb in the picture.

 

[Maker]

Here it is, on a neat little bracket;

And I know you want to check my wiring;

Neutral is black because it was 4 core cable with only earth, grey, brown and black.

I don't have any strain relief on the cables yet and I don't have any clips to run the cable along the wall yet either. The motor does run though so I'm happy, now to sort out the really tight belt tension and then I can finally use the bloody thing.

 

[Maker]

Just thought I'd mention it, y'know, because I hear there are people who can't sew or plait a woggle

I did just learn to sharpen drill bits on a bench grinder so who cares about sewing and plaiting skills.

 

[Robotstar5]

Glands are cheap enough and should be fitted before vibration starts chafing the insulation.

 

[dobbslc]

Stuffing glands are what you want, before you snag one of the cables and pull it out!

 

[Maker]

I've asked dad to get me a couple from work.

 

[Maker]

Here it is, with glands fitted;

The black one is the supply and should really be replaced with some conduit back to the wall. The white one in the box section is cut down and glued in.

 

[Maker]

That would be great, thanks.