Wiring a compressor control board in to garage?

[JOEPRO]

I have just bought a used tandem air compressor. Single phase, 32 amp supply required.

I recently installed a new dedicated 32amp welder supply to my rear garage. So I have the correct sized supply there already which I can tee off. (It has a type C breaker etc and works perfectly)

My question relates to the best way to wire in the compressor control board. It looks like this:



This is mine inside:



There is a red rotary isolator inbuilt to this panel.

Is it OK to bring the 32 amp supply right into the board? (For clarity it is fed from an RCD protected type C MCB in my main garage)

Or would I need to leave off a 32 amp socket beside it (can include isolator) and plug the panel in instead? So in effect it may not be considered as a part of the fixed electrical installation of my garage.

 

[AVI_8]

The way I‘ve seen one of these wired in the past was the supply going straight to the compressor board, however I don’t see why it would be wrong to put a 32 amp plug on a cable, that way you could just unplug the compressor when you want to use the socket to weld. I‘m not a spark though.

 

[JOEPRO]

The welder socket is near the door and I have a cable which reaches the whole garage for the welders. Works great so I don't have a "need" for a second 32 amp socket but I suppose it certainly won't do any harm to have it.





I would like to mount the compressor control board up high on this wall:



The compressor will be in the loft above, well ventilated and visible from a large hatch.

 

[brightspark]

you can wire it in direct as a radial as its fitted with an isolator .if u have no need for an extra socket its pointless fitting one

 

[addjunkie]

Id use a socket, to stopyou trying to use both at once

 

[JOEPRO]

Id use a socket, to stopyou trying to use both at once

Fair point but the panel can still be isolated and 99% of the time the compressor will be off anyway.

I'm the only one using this garage and I'll know not to overload anything.

 

[JOEPRO]

you can wire it in direct as a radial as its fitted with an isolator .if u have no need for an extra socket its pointless fitting one

Thanks for that, yes I think I'll keep it simple and use the panel isolator.

I'll take it as a radial from the current welder socket and protect any exposed cables in conduit.

 

[brightspark]

Fair point but the panel can still be isolated and 99% of the time the compressor will be off anyway.

I'm the only one using this garage and I'll know not to overload anything.

and even if u did it would just knock the breaker off

 

[JOEPRO]

I can do better than the PO anyway. He had it connected to a 2.5 T&E and a 13amp fused spur.

It still worked though but it's supposed to be 32 amp feed

 

[AVI_8]

I can do better than the PO anyway. He had it connected to a 2.5 T&E and a 13amp fused spur.

It still worked though but it's supposed to be 32 amp feed

View attachment 398335

How inventive of him !
Even 4mm is I’m sure? only rated to 30 amps when in conduit.

 

[brightspark]

both running will be about 24 amps but if ones running and the other starts up 5 seconds later it will take it up to nearly 30 amp for a few seconds

 

[Jack_K]

I can't answer the legality of either way but I would wire it direct without a plug and socket. It would reduce failure points and take up less space.

 

[Turbo]

Does that control box operate a solenoid valve on each pump to allow the motors to start up unloaded? If it doesn't you should only use the red knob on top of the black boxes to start & stop each pump.

 

[JOEPRO]

Does that control box operate a solenoid valve on each pump to allow the motors to start up unloaded? If it doesn't you should only use the red knob on top of the black boxes to start & stop each pump.

There is a central black box unloader valve on the compressor itself. This when activated turn the pumps on and off.

The control box allows selection of either the left pump, right pump or both being powered up on demand.

 

[Agroshield]

The compressor will be in the loft above, well ventilated and visible from a large hatch.

If the compressor is in a different room to the control box, would it be prudent to put a simple isolator adjacent the compressor itself?

In the photo in your original post, the white 3-core cable coming into the top of the box looks skinny compared to the internal single core wires.

 

[8ob]

I have never understood why you can’t draw 30 amps off a ring main, it’s fused at that in the board and as long as you aren’t drawing this off a spur your outlet should have 2 x 2.5 cables feeding it
Not saying it’s ideal but is it really a disaster?
Bob

 

[JOEPRO]

If the compressor is in a different room to the control box, would it be prudent to put a simple isolator adjacent the compressor itself?

In the photo in your original post, the white 3-core cable coming into the top of the box looks skinny compared to the internal single core wires.

Well its 2no cables serving the pumps and also another cable to the black box. So 3x isolators would be needed.

Yes the wire gauges are all over the place and incorrect. I'll be redoing that.

 

[JOEPRO]

I have never understood why you can’t draw 30 amps off a ring main, it’s fused at that in the board and as long as you aren’t drawing this off a spur your outlet should have 2 x 2.5 cables feeding it
Not saying it’s ideal but is it really a disaster?
Bob

You maybe could I'm not sure. My back garage has a single 2.5 T&E feed for the LED lighting and general sockets.

And a separate dedicated 32amp welder power supply. (6mm2 cable IIRC) So in this case it makes sense for me to utilise a radial off the welder supply for my tandem compressor.

 

[Agroshield]

Well its 2no cables serving the pumps and also another cable to the black box. So 3x isolators would be needed.

Could you route the incoming supply to the control box up to the loft, through the isolator and then back down to enter the box? For no real reason, it just strikes me as potentially useful to be able to switch the machine while you are looking at it.