Single phase from three phase sockets?

[reb78]

I have a number of single phase machines (180 amp Oxford arc welder, 180amp mig and plasma cutter Cut40) that really need a 16 or 32 amp supply. The Mig and Plasma are currently on 13amp plugs.

I have a number of three phase sockets around the shed but the single phase is just normal 13 amp.

Can I run 16/32 amp plugs from one phase of the three phase sockets with an adaptor lead or are there reasons not to so this? I have some spare points at the distribution board so could get dedicated supplies put in but of i can avoid that it would make things quicker!

 

[WorkshopChris]

Yes if the neutral is wired and they are 5 pin not 4 pin.

 

[Pete.]

As Chris said above. The only possible problem is if the 3 phase is rated much higher than the equipment demands. If there's a fault in the plant or cable it might all catch fire before the supply trips out.

 

[hotponyshoes]

I don't know if you are supposed to do it but it does work.

I have the 5 pin sockets in a workshop and you can just wire the single phase to one of the phases, nutral, and earth.

If you are going to be doing this on more than one machine I would wire each plug to different phases to spread the load over the 3 phases.

Another thing to bear in mind is that the 3 phase breaker may be 3x16a so you might not actually be able to pull 32A from it.

A lot of the newer breakers will trip out if they detect an imbalance inbetween phases as well so that might be something to consider

 

[pressbrake1]

As Chris said above. The only possible problem is if the 3 phase is rated much higher than the equipment demands. If there's a fault in the plant or cable it might all catch fire before the supply trips out.

He wants to use three phase plugs on a single phase service

 

[hotponyshoes]

If you have single phase plugs on the kit already then it might be better to make up some 5-pin plug to 3-pin socket adaptors ,
You could make 3 and have each on a separate phase.

Edit, I see you have already mentioned adaptors above!

 

[WorkshopChris]

A lot of the newer breakers will trip out if they detect an imbalance inbetween phases as well so that might be something to consider

How would that work, its a new one to me.

 

[reb78]

Thanks. Some are four pin and some five. I will check what the breakers are rated for on the five pin circuits.

If it makes any difference, its only me in there so I cant think of a situation where two of the machines will be running at the same time.

 

[hotponyshoes]

Don't know.
Its probably the 3 phase version of an rcbo?

I got a large lamp on a trolley for paint drying.
It was used, tried it at the guys place and it worked fine, it was on a 3phase plug but a single phase unit.

Got it back and plugged it into my 3phase socket by the booth and it tripped it out. Sparky said it was because the breaker (newish) was detecting an imbalance between the phases. I fitted a longer lead and it works fine on a 16a single phase socket.

 

[Pete.]

Thanks. Some are four pin and some five. I will check what the breakers are rated for on the five pin circuits.

If it makes any difference, its only me in there so I cant think of a situation where two of the machines will be running at the same time.

If some are four and some are five pin then move a 5 pin outlet to the handiest spot and make up a patch lead so you can run it out to any of the single phase machines you need to power.

He wants to use three phase plugs on a single phase service

That's not how I read it. Seems to me he wants to pull single phase out of a 3 phase service.

 

[pressbrake1]

Read it properly now.
I’d be putting that Oxford stick welder on two phase and it will be much better.

 

[WorkshopChris]

Sparky said it was because the breaker (newish) was detecting an imbalance between the phases.

Sounds very strange to me as you will always have a imbalance between phases( as the voltages will never be exactly the same -so current draw varies). a 3 phase rcd still works in the same way as single phase detecting the difference in whats going out and coming back in.

 

[brightspark]

that sounds very iffy to me a bit of bs because he cant explain it if that was the case and you have a 3 phase board with mixed 3 phase and single phase breakers the main rcd would not stop on rcd work on current imbalance so if you take off one of the phases and use the neutral the load is balanced