Any mains electricians on board?

[some bloke]

My new lathe twice out of maybe 20 starts did what I'm calling a hard start - with a thunk that knocked the power supply to my workshop off.

First check was the fused spur indoors - 3 amp fuse was fine. Then noticed my PC had force stopped - yup no ring main!
Checked that fuse = OK...

House lights were still on indoors. RCCB section circuits on the fuse board had tripped, mains was still available to lights & cooker.

Do I need some kind of Anti Surge adaptor - or whatever?

[terry1001]

I'm not an electrician but I know that a lot of motors draw much more power to start than when running under load. If you have extension leads as well that could be enough to trip the circuits although the normal way they go is a leakage to earth.
Is there anything which is adding load to the lathe making it harder to start spinning? Is this one of the lathes with electronic speed control which need to be started with the control set to zero and then turned up?
Hope there is something here which helps.

[SikaStag]

Dave
I would say a 3 amp fuse is way too low. How long is the extension cable you are using.

I have a 32 amp feed going to my machines in my workshop. all through extensions cables that are the proper armoured type for that rating. here should be a plate on the motor of the lathe that should give you the amps it runs on. Great advice from terry. Have the speed control at minimum and make sure the power feed is disengaged.


Ian

[Marky610]

I am an electrician and it's nothing to do with your fuses

It's your MCB, most domestic circuits are fitted with 'B' type MCB's

You need 'C' type for inductive loads like motor's, allows for a larger starting current

[some bloke]

Cheers chaps, it's an induction motor according to the plate on it, 550W, 57 amp??? power rating 3/4 HP fuse rating 13 amps. Its not one of the variable speed ones. http://www.machinemart.co.uk/shop/produ ... etal-lathe

The power supply to it is a 3 amp fused spur off the ring main, internally sub spurred from within the back box via armoured underground cable to the workshop, maybe 12 feet long. The original plan was that I would only ever need a pillar drill and band saw in addition to two 30 watt 3ft strip lights in there.


Thanks Marky, This is the culprit then:


Can it be swapped for the C type that you suggest?


I have this in my conservatory which is quite close to the workshop - would there be any benefit running the lathe from this via a short extension lead, or could that just be a similar thing to what I have in the fuse box?



The house is about 20 years old so it could be that the consumer unit is obsolete and the required component is unavailable. If the likelyhood of getting a C type is out of the question would there be some kind of transformer that sort of stores enough electricery in coils or whatever to smooth the whump?

[some bloke]

I've set the belt to a lower head speed - seems ok now thanks chaps.