Workshop CU setup

[Vinny]

I know this has been covered umpteen times and I've had a good scan through but nothing really answers my question.

I've a CU in my workshop with a 63A RCCB, the ring for the sockets (ergo - the machinery) is on a 32A breaker. The workshop CU is fed from a 32A breaker on the house CU (this strikes me as being strange - a 32A breaker feeding a 63A RCCB??).

The reason for posting is that I'm thinking seriously about getting Corsets Wadkin PT, my main concern was that such a beast may be too much for my existing set up........however I'm thinking that the workshop ring at 32A would be more than ample.

Can anyone tell me if this is the case.

Cheers

Vinny

 

[Digit]

The 63Amp is the maximum LOAD that the device can handle and has nothing to do with 'safety' current, which will typically be 15-30 Milli amps.
Provided the sub circuits in you shop have their own MCBs the 63 Amp is not of great consequence.
Is the RCCB fed from the output side of the 32 Amp device or the input side?

Roy.

 

[Vinny]

its fed from the output

 

[Digit]

Which means that your shop is protected at 32 amp load, 64 would be a hell of a short circuit!

Roy.

 

[Vinny]

cheers digit

 

[WoodAddict]

what's the power of the PT you mentioned? (wattage)

 

[Vinny]

according the axi web site its 1500w

 

[WoodAddict]

Amps = Power / Voltage

1500/230 = 6.5 amps

Not a lot of power really. You should be fine with what you have.

 

[paulm]

Seems maybe a bit under powered, is it single or three phase ?

Cheers, Paul

 

[Vinny]

Paul, its single

 

[woodbloke]

Amps = Power / Voltage

1500/230 = 6.5 amps

Not a lot of power really. You should be fine with what you have.

Fine if the motor's dc, but the calculation for ac power is somewhat different. I used to be able to do this sort of thing but that was a long time ago in a different life. The main thing is that the machine will probably run from a 13A, but the start up current will briefly exceed the capacity of the ring main, so it needs to be run off a 16A type 'C' breaker.
I'm currently going through the same sorts of problems with sorting out future kit and 'electriceral' issues...Bob9Fingers is your man and will definitely give the 'yae' or 'nae' (he's given me loads of invaluable info to date) so I'd suggest you contact him when he returns from Cyprus - Rob

 

[WoodAddict]

Amps = Power / Voltage

1500/230 = 6.5 amps

Not a lot of power really. You should be fine with what you have.

Fine if the motor's dc, but the calculation for ac power is somewhat different. I used to be able to do this sort of thing but that was a long time ago in a different life. The main thing is that the machine will probably run from a 13A, but the start up current will briefly exceed the capacity of the ring main, so it needs to be run off a 16A type 'C' breaker.
I'm currently going through the same sorts of problems with sorting out future kit and 'electriceral' issues...Bob9Fingers is your man and will definitely give the 'yae' or 'nae' (he's given me loads of invaluable info to date) so I'd suggest you contact him when he returns from Cyprus - Rob

This calculation is fine for AC. You are right to think about start-up current and Type C breakers but you should not back up a 6.5amp machine with a 16amp fuse! That's far too big. If it's a ring main then it should be a 32amp circuit. With a 13amp fuse in the plug-top you'll be fine.

Paul

 

[OldWood]

I rebuilt my saw bench with a 2.1kW motor - care of a skip !! I did have to adjust the electronic starter timings and in due course I did transfer it to a dedicated 16A circuit but it only took the 13A fuse out occasionally before I changed it over. The point is that 1500W motors are used in quite a lot of household equipment - high pressure washer, lawn mower, garden chipper, hydraulic log splitter, etc. and work quite happily off 13A sockets.

Rob