Lathe trips Consumer unit, any ideas why?

[Chris152]

As I was turning yesterday, my lathe tripped the fuse box thing. I reset it and started the lathe again - fine til it reached a higher speed when it tripped again. This happened a few more times so I left it alone, came back after 20 mins and all was fine - and subsequently used the extractor on the same extension (as usual) and all was fine. Any idea why this might have happened? The only thing that's different today is that it's quite hot (air temp, I mean - the motor was just a bit warm to the touch).
I know nothing about electrics so don't know if it could be potentially dangerous (and quite possibly won't understand the advice if it's remotely technical).

Thanks

Chris

 

[sunnybob]

was there any water about? spills, power washer, mopped floor?
Even very humid? An old power cable can be become abosrbant and short between live and neutral.
Check the whole power line, any kinks, chafes, tied knots?
After that it becomes a bit arcane.

 

[PlacidCasual]

I’m no electrician or electrical engineer but you do get different types of MCB most domestic ones are very twitchy. You can get ones with the same rating that are less twitchy your electrician can advise. 5minute job to swap it out.

Basically motors can temporarily have high starting loads and the coils in motor will react to the load you place on the chuck. That would be my first guess but ask a sparky.

 

[aesmith]

What exactly is it tripping, is it an MCB (normal circuit breaker to protect against overload or shorts) or is it an earth leakage type breaker and RCD or RCBO? A photo of the thing that trips will probably tell us. Either way it sounds to me like a fault in the lathe, normally if it was a simple overload it would trip the breaker on startup.

 

[Chris152]

This is the consumer unit:

It's just for the garage and extension, and sometimes trips when I switch the washing machine on, but that's a cold start - this happened as I was increasing the speed on the lathe, so it was already warm and running. And then accepted a much higher load (with the extractor) no problem. It's all worked fine with the present setup since I got the lathe about 5 months ago, used pretty regularly.

One thing I thought of after reading yours Bob - the garage is actually a fair bit cooler than it's been outside. Is it possible that hot, humid air came into the cooler environment and condensed on the electrics?

Thanks all.

 

[SteveF]

what lathe is this?
my axminster 1416vs done this until I swapped out the mcb

Steve

 

[sunnybob]

Humid air wouldnt affect the wiring unless it was extremely old and cut to pieces. Wiring laying in a puddle could be a problem even if the insulation is not cut.

I used to do a lot of fault repairs on electric machines, and nuisance trips are THE hardest things to fix, especially from a distance.
But THE most likely from my experience, I'm hesitant to suggest as you say you have zero electrical knowledge.
Assuming one of those mcb's is the lights and the other is the power, and its ONLY the power that trips?
Then I suspect you have a loose neutral connection on the board. Heres the reasoning;
The fact the washing machine trips it shows it isnt the lathe. The fact the lathe and or washing machine doesnt trip it every time shows its not a fault with either.

What happens is the loose wire sometimes makes or breaks the connection. When the current surges as from turning on or up, and the wire happens to be in the breeze at that time, there is a rapid pulse spark, just like a car spark plug. That spark will trip the mcb. Next time, the wire is laying firm against the connection and its 100% fine.

If you can FULLY isolate that unit from the house electrics, then pull the front panel and inspect ALL the wires into everything. Tug them quite hard. Any thing that looks lop sided or worn or burnt or loose, repair it and tighten down with a fair amount of force (by hand, no power drills).

If thats all ok, move along to the 13 amp wall sockets and again, tug every wire including the earths.
If on the other hand its the double isolator that trips, then you have to add in the lighting circuit. Does it ever trip when the light switch is operated?
As always, other options are available and it could be both machines, but thats where I would start looking.

 

[Steve Wardley]

We had a twitchy circuit breaker on some shed lights at work, they would trip out on switch on and our sparky said it was the circuit breaker at the limits of it's tolerances and he fitted a slightly higher rated one and all is fine now.

 

[Chris152]

Right, that's all sounding a bit beyond my confidence level! It's just the power circuit that can trip the switch - the lights have never done it. The lathe's about 20 years old, as is the Dart speed control so maybe something's not happy in there. All the cables look fine, but I don't feel comfortable isolating things/ looking inside. I have a couple of dodgy light switches elsewhere in the house so think maybe I need to get someone in to take a look at the lathe and switches at the same time, kind of a job lot.

Thanks, I really appreciate your advice everyone.

C

 

[Sheffield Tony]

So which of the trips in the picture is going ? The RCD (with test button) or MCB?

Our VAX tripped the RCD, was due to failed capacitors in the EMI suppression filter. As the machine said 2kW on it, but the filter said 6A max, it is probably not surprising that it is a common fault.

 

[Chris152]

It's the big one on the left that switched itself off - the same one the washing machine does once in a while (over a period of several years, the washing machine's done it maybe 6 times). Sorry to be hopeless - does that help?

 

[johnnyb]

My saw tripped the electrics when the capacitors leaked. A friend's lathe needed a new motor after his kept tripping( record power). If it's on a speed controller(vfd) these can also trip rcd.

 

[aesmith]

The RCD will trip if there's an imbalance between current going out on the Live and coming back on Neutral, which means that some current is going to earth. However you said the washing machine sometimes trips it as well, so it could be a faulty RCD. A sparky would be able to test, their gear can test that it doesn't trip until the correct threshold, and that it trips in the required time when it's over the threshold.

 

[Chris152]

Sparky can't come til next week so I went ahead and used the lathe today. All fine for about an hour, then the same cutout thing, tripping the RCD.

Hypothetically (ahem), if you were to be silly enough to rotate the headstock so the exhaust for the fan in the motor were pointing directly at a wall at a distance of 1cm, maybe a tad less, on a hot day, could that cause it to overheat and cut out/ trip the rcd?

 

[Sideways]

Overload would trip the relevant MCB (the the two narrow ones on the right) that's their reason for being there. Those aren't tripping so you most likely don't have any serious overload to worry about.
Overload should NOT trip the RCD (wide one with yellow button). That is there to protect you in case of a wiring or other fault allowing electricity to flow where it shouldn't. You seem to have a fault with what the RCD is there to look after and that could be in the power OR the lighting circuit, you can't tell unless you switch one of them off and the fault keeps happening regardless.

So: wiring can go wrong over time due to age / deterioration / damp / overheating / wires shorting out because vibration or pressure has damaged the insulation ... all sorts of reasons.
As others have said, the RCD could be faulty and tripping when it shouldn't.
Electrical circuits designed to filter out electrical noise (you find them in computers, washing machines, ...) cause a small amount of leakage as part of their operation so a change in something like that could be a source of your problems.

Let your sparky fault find. You should be OK for a few days as long as the RCD resets OK each time after it trips.

 

[Chris152]

Thanks Sideways, you managed to explain that on terms I think I understand! I was hoping it was just overheating and the fix was simply to pull it further out from the wall - I'll definitely get it checked properly.