Mixer is short circuiting my house!

[Llarius]

Hi, I just bought my wife a metcalfe (professional catering equipment) sm5 mixer from eBay and picked it up today. It was demonstrated to me to be working when I went to pick it up, but when I got it home and plugged it in to our mains it wouldn't work, and then I noticed neither would anything else in the house! I checked the fuse box, and yes it had blown the fuse.

I don't know anything about electrics, but am sure there is something wrong with the setup on this thing. I've checked the machine itself which has some details on the unit with a serial number which says that it is a 230v 1.5a machine. The plug that is attached to it says 250v 13amp. Is that where the problem is going to lie, and if so why do it work at the buyers house but not mine?

Any help appreciated, as I say I know nothing about electrics, and I was rather hoping to score some brownie points with this rather than just wasting some (but thankfully not too much) money!

 

[mfarrow]

What was it that 'blew'? Was it definitely a fuse blowing or did it trip an RCD or an MCB? Did it have a test button on it? If you press that test button, does it trip the same thing that went earlier?

Also if you can open the plug check it's been wired correctly, i.e. blue to neutral, yellow/green to earth.

 

[EFLImpudence]

You say fuse.
Did you have to replace an actual fuse or fuse wire?


If you just had to switch it on again, was it one like this which tripped -

Or one half the width with just a switch.

The amp ratings you mention are not the problem.
Although the plug is marked 13A it should have a 3A fuse in it.

 

[Llarius]

Thanks for coming back to me so quickly - I wasn't expecting that!

Ok, so I think i've proven I know nothing about electrics...to try and make it a little easier I have tried to add some images to show you what happened! Hopefully they will help.

Here is the rating on the mixer itself:View media item 45745
I think when I said blown a fuse I meant tripped our circtuiry? Here is what tripped:
View media item 45743
and more specifically this switch was what tripped and dropped to a half way point. I pulled it down and pushed it back to the upright position after unplugging the mixer to reset everything:
View media item 45744
If I'm completely honest I have never noticed the "Test" button and wouldn't really know what it is testing, or what the purpose was for.

I checked inside the plug and it seems to be ok, but do notice that the fuse says 13a not 3a like suggested above by EFLImpudence:
View media item 45748
I'm also puzzled as to why it would work in someone else's home but not ours?

Oh - does it help to know that it was cleaned as soon as we got it home? A bit of fairy liquid and anti-bacterial spray (it looks completely sealed so I wouldn't suspect this being a problem), and wonder if any got to any of the electrics?

Thanks again!

 

[SimonH2]

That device that tripped is a Residual Current Device (or what some people still call and earth leakage breaker). It trips if there is leakage current from anything live to somewhere it shouldn't. Basically the type you have there compares the current that goes out the live wire with what comes back through the neutral wire - if there's too much difference (more than 30mA) then it trips. It's there primarily for personal safety - if something is live because it shouldn't be (should normally require 2 faults) then it should trip the supply rather than allowing someone to get a possibly fatal shock.

It's obvious that your mixer has a fault and is passing current between live and earth, or possibly has a short between neutral and earth. It will have works at the seller house because they don't have an RCD and so they'd be oblivious about the fault.

You need to get someone competent to take a look at the mixer - it has a fault, but you can't really blame the seller for not knowing about it unless they were trade (in which case they are liable.)

EDIT: Yes, damp could cause it, and yes it should probably have a smaller fuse in it - quite likely 3A but see what the handbook says.

 

[Llarius]

Thanks Simon, I guess that all makes sense. We live in anew build and the sellers house was a Victorian London terrace. I guess we can try it again in a few days to see if it was damp problem from cleaning?

Also one of my colleagues husbands is a PAT tester, I assume he should dabble to tell me if it is faulty but not necessarily exactly what or how to fix it?

As a last resort I suppose I can give metcalf a call.

 

[SimonH2]

Also one of my colleagues husbands is a PAT tester, I assume he should dabble to tell me if it is faulty but not necessarily exactly what or how to fix it?

He should certainly be able to tell you it's faulty, whether he can fix it depends on his capabilities/qualifications.

Am I the only one who finds the phrase "PAT Test" (which literally means Portable Appliance Test Test) a bit odd even though it's easy to say ?

 

[EFLImpudence]

PIN number is the same.

 

[conny]

Its only 280 watts so as EFLI says, a 3A fuse is large enough.
If you type sm5 into Google it will come up at the top of the page and give you some more info.

 

[Llarius]

Please excuse my ignorance, if I put a 3a fuse into the plug what should this do for me? It wouldn't solve the problem I've been having will it? Don't get me wrong if that is better for it and I can get this mixer to work I will change it but I just want to understand why I am doing what I would be doing.

 

[bernardgreen]

The fuse limits the current that can flow. Thus it limits the amount of power that can be created in the appliance. Normally the appliance will limit the current and power to what is necessary and safe for the appliance to work. But if the appliance becomes faulty, such as a short circuit the current may not be limited by the appliance and the power created will burn out the appliance or the cable leading to the appliance will burn.

13 amps will allow about 3 kWatts (3000 watts) of continuous power, a 3 amp fuse will allow about 700 watts of continuous power. For a short time they will allow a lot more power as the fuse takes a second or two to melt and blow.

With the 13 amp fuse in a fault condition the mixer and its cable could heat up like a 3 kWatt electric heater and the fuse would not blow. With 3 amp it could in a fault condtion still get 700 watts of heat but that is often less dangerous than 3000 watts.

 

[Llarius]

Also I know that it hasn't been too long since we washed it and the temperature in the lounge where I have left it isn't particularly high, but I wanted to see if this was because some water had gotten to where it shouldn't.

I plugged it in and it actually started to work this time which it wouldn't do at all yesterday. I started to turn the speed know up and it carried on working until I got to about half way round, at which point everything cut out again and I had to reset the electrics.

Would this suggest that something is still drying out? I hadn't really noticed it when we were cleaning it, but a couple of the knobs are a little loose and could have let some water in - or this could be wishful thinking!

 

[Llarius]

The fuse limits the current that can flow. Thus it limits the amount of power that can be created in the appliance. Normally the appliance will limit the current and power to what is necessary and safe for the appliance to work. But if the appliance becomes faulty, such as a short circuit the current may not be limited by the appliance and the power created will burn out the appliance or the cable leading to the appliance will burn.

13 amps will allow about 3 kWatts (3000 watts) of continuous power, a 3 amp fuse will allow about 700 watts of continuous power. For a short time they will allow a lot more power as the fuse takes a second or two to melt and blow.

With the 13 amp fuse in a fault condition the mixer and its cable could heat up like a 3 kWatt electric heater and the fuse would not blow. With 3 amp it could in a fault condtion still get 700 watts of heat but that is often less dangerous than 3000 watts.

So even for just testing it I should really change that fuse?

 

[bernardgreen]

Yes change the fuse,

if I put a 3a fuse into the plug what should this do for me? It wouldn't solve the problem I've been having will it?

No it won't solve the earth leakage problem. That is a result of damp. damage or wear and tear in the appliance. Was it brand new or is it "previously used" and thus maybe wear and tear has had an effect. It is said to have a DC motor and these often have carbon brushes in contact with a rotating shaft. The brushes wear and often create carbon dust which can build up and create unwanted circuits between wires and the metal work. These circuits are not enough to prevent the motor working but are enough to create earth leakage currents large enough to trip the earth leakage protection, the RCD, in the consumer unit as yours is doing. Stripping and cleaning is then necessary.

EDIT Just read the post that it worked until the speed was increased. That does suggest damp MAY be the problem.

 

[Llarius]

It is pretty well used judging by the marks or scratches on one side. Ah well, I'll change the fuse to 3a and give it another go in a couple of days o see if it is a damp problem.

If not, you all sound like you know what you are talking about, do you think it would even be worth considering paying someone to open it up and attempt to fix it or would I be better to cut my losses?