Lathe shocks

Hi

I think I have an issue with my lathe... can't be sure yet... but I think I get small shocks from it sometimes. I mean electric shocks. Obviously it's not from the 240V wall because I would be sure if that happend

It feels like small electric shocks... but only sometimes... not even most of the time. It's not those static charge shocks like when touching metal (e.g. closing the door of a car... which is why I only touch the window now) because I get those a lot and know how they feel.

I also suspect it's something to do with me... like I get those static shocks a lot, after I felt I got a couple of shocks my girlfriend touched the lathe in any way that I did, even much more, and couldn't get a shock at all.

It's an Sieg SC3 and I double made sure all the wires were ok and the same as the instructions on ARC's website, except mine has four ground wires as opposed to three in the instructions.

After a while I stopped getting them and for the last half hour of working with the lathe I got none.

I'm just wondering if someone got them before and can suggest if I'm not imagining it and why it might happen?

Thanks

I would check all the earth connections again first to make sure they are correct. Make sure there is an earth connection from the motor to main earth connection. Check the plug earth and make sure that the socket that you plug into are earthed.

Bri

I would agree with Bri, I got called to a working machine in a customers a while ago, everytime somebody used the machine they got a shock particularly every time they touch it, I checked all of the earth connections and found that the plug earth had come loose, I remade the connection and the problem went away.

Martin P

Thanks.

I couldn't get another shock now that I touched all the parts again... but I checked a few thigns anyway.

There are four earth wires connected to the headstock. One is coming from under those black plastic round blocks at the bottom. One is inside the thick black sleeve that wraps around a few wires, coming under the head on the right side of the photo (from the operator's POV). Two are coming from under the head, just under the 2nd from left in the photo.

I don't remember everything, but I think one is coming from the wall cable itself, one definitely from the electricity board on the "back" of the head (operator's PV), one from those round blocks and the last... I don't remember. Maybe from the motor itself? I'm not sure. I don't think the order matters but I installed back the same as they were before just in case.

You can see the plug itself only has two prongs... but isn't it supposed to be this way?
The wall socket is just above a table reinforcing bar, so if the plug had three prongs it actually wouldn't fit now. I have to connect it upside down. Should I change to a three prong plug and somehow manage to fit it?

Though if the shock would be from the 240V from the wall I would definitely know it... no? 

Sorry I really know next to nothing about anything electric.

Edited By Nitai Levi on 02/08/2015 07:35:40

Of course you should check the electric safety aspect.. but I recall owning one pair of shoes that gave me frequent static shocks whenever i earthed myself. Leather soled and on a polished lino foor I could manage a 1" spark from me to a radiator...

Nitai,

Your plug is a european type, the earth is the flat steel band which runs between the two pins and will make contact within the socket.

Martin P

Thanks

pgk pgk, I've tried with and without shoes... I think it happened both times...

martin perman, yes, but being flat, it only touches the plastic of the wall plug since it's not getting into the hole itself. Is that how it's supposed to work? I know some wall sockets have metal bits sticking out for the earth.
If the shock was the 240V from the wall wouldn't it be obvious and much stronger?

The wall socket looks like this:

If I search for European socket they mostly look like this:

Edited By Nitai Levi on 02/08/2015 08:22:16

Edited By Nitai Levi on 02/08/2015 08:23:05

Nitai,

I've never seen your socket type, I'm used to the second type you show which would suit your plug.

Martin P

Nitai,

Are you in Israel as your socket is particular to that country so you may have to change your plug as its incorrect for the socket.

see this

http://www.worldstandards.eu/electricity/plugs-and-sockets/ at style H

Martin P

Yes. I guess I should look for an adapter? Do the metal parts on both the top and bottom of the European plug mean I could use a an adapter (if I find one) both ways (i.e. either one could be used for earth)? Or should I change the plug? Molded plugs are more reliable... I would prefer not to change it... unless I have to.

You can place a european plug either way so the metal earth strip will always be in contact.

Martin P

Your plug is NOT correct for your socket because the socket has neither the male earth pin or the earth pin fingers as shown in the second photo. Your machine is NOT earthed and is potentially dangerous.
The socket you show requires a plug with 3 male pins. I would cut off the existing plug and replace it with the correct plug. If you are not confident in doing this, you should seek a local contractor who does understand your system. As others have said, you could use an adaptor, but for me, I would change the plug as some adaptors are not particularly well made.

**LINK**

In the above, your plug is for types 'E' and 'F' and your wall socket is type 'H'

In any case, you should NOT use the machine until you have changed the plug or use the correct connector.
Bob H

Hello Nitai,

Yes your plug and socket may well work together, but you are not making the earth connection - change it immediately!

Neil

OK thank you. I'll see if I can get a decent quality local plug to replace it with. I have made/soldered audio cables and electricty switches and cables before... but never ones with earth, only low voltage transformator cables. I'll look into this and possibly ask someone else. Unfortunately I can't say it's surprising that the store is selling lathes with European plugs without mentioning anything about it... Thanks again.

Edited By Nitai Levi on 02/08/2015 09:24:44

i had exactly the same problem on my Sieg C4, changed the mickey mouse plug, end of problem

If you are getting a shock, then you have leakage to earth and should not use the machine until you get it checked out by an electrician.

The earth wire is there to enable the circuit breaker or rcd to work and disconnect the supply safely so you do not get a potentially lethal shock.

Without an earth , you are completing the circuit the earth wire would have made.

Do not play with mains electricity if you do not understand the consequences.

The leakage to earth is probably due to the reactive current through the capacitors inside the mains input filer which will probably be part of the speed controller. It would be wise to check for leakage with an insulation tester which will use DC so will not show reactive current through the capacitors. Do not set the insulation tester to more than 500 volts or it will probably destroy the capacitors in the filter.

Les.

Looks like you should change the plug to suite the sockets for what ever part of the world you are in. Alternatively you may find that you can buy and adapter but take care. In the UK there are 2 types that accept the European plug you have, one adds the earth connection and the other for electric shavers etc doesn't. The earth connection is on the side of the european plugs - sometime sort of bent over onto it.

If you post a photo of the colours of the wires if you change the plug many on here can tell you which one is which. If your plug is fused the live connection will go to that.

There can be another reason for this problem but it's more common on older lathes that use brushed motors such as hobbymat etc. The carbon from the brushes wears to fine dust and coats the inside of the motor. The answer to that is to dismantle the motor and clean it very thoroughly.

John

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The plug you show is a universal European type. Some European countries use a male earth pin in the socket and others use side contacts for earth. Older Europen plugs are country specific and not interchangeable like that.

What country are you in? I've not seen a socket like yours before.

Russell.

I'm in Israel and that's a standard socket here. Male plugs with earth here use three prongs to fit the three prongs in the sockets. Pretty poor service from the store to ignore the fact that the lathes come with European plugs and don't have earth here... which is expected...

I'll look if I find a relaible adapter with earth. If not I'll chage the plug, though I'm not sure if I should do this myself or not. I had supposedly very good electricians make (solder) cables for me in the past a few times and in all cases they did a far worse job than me. I've been doing it myself since then, but never dealt with mains.

The current plug is molded together with the cable over the wires, so the question is, if I cut it, how do I know which wire goes where?