Dryer keeps causing circuit breaker to trip - help plzzzz

[Gizmonster]

My friend has a tumble dryer and she recently moved house.
At her last house, her main fuse box consisted of the old-style removeable fuses and she had no problems whatsoever with her dryer.
She's recently moved house and this house has circuit breakers - the ones that you can flip back on when they "trip".
For reasons unknown - the dryer keeps tripping out the main circuit breaker, causing all the sockets downstairs to go out. She's checked the plug and fuse, etc - even tried plugging it in different sockets ..... all to no avail.

Has anyone any ideas what could be causing this - and more importantly, how to resolve it ????

Thanks in advance.

[heathfield]

A typical tumbe dryer might use 2400 watts. This is less than a 3kw electric fire, or a 3kw high speed kettle, both of which should operate comfortably from your affected sockets without tripping the breaker switch. I suspect there's a fault on the dryer.

[BRIGHT SPARK]

When you say the main circuit breaker do you mean the RCD unit.If this is the case then there is an earth fault in the appliance.However if it is an MCB thats tripping then you either have a circuit overload or a short circuit in the appliance.

[Gizmonster]

Ok - dumb question time lol:

What's the difference between MCB and RCD ???

We've tried switching most of the other appliances off, so as to not overload the circuit, but it keeps tripping.

[BRIGHT SPARK]

An RCD will have a small button on the front and it will be marked TEST.It will also have a switch.
An MCB will normally just have a switch.

[Gizmonster]

I'm assuming that an RCD is one of those that you plug in, so if, for example, I'm mowing the lawn and I cut through the cable, it'll stop me getting an electric shock.
The switch in question is what used to be the old style removable fuses - now replaced with these new style trip switches.
The dryer worked fine in the last house, where she had the old style fuses and it worked fine for a while in this new house. After a while, it started tripping out, but the dryer would work for 30 mins, maybe even an hour, before it tripped the trip switch.
Now it's just causing the switch to trip straight away - yet the dryer isn't even switched on ...... as soon as it's plugged into the socket, it causes the circuit to trip out.

Any ideas plzzz ???

[BRIGHT SPARK]

Check for damage to the flex at the cord grip and where it enters the appliance.check the plug again.If all seems ok get a competent person to check it out with a tester.
If its tripping out the MCB when its plugged in but before its been switched on at the machine there must be a fault before the machine switch unless the machine switch is at fault.Try taking the plug off,cutting two inches off the flex and re terminating it.Sometimes damage can occur unnoticed caused by the cable flexing at the cord grip.

[BRIGHT SPARK]

Firefly...Giz said that the rewirable fuses had been replaced with new trips.so it has been sugested that it is an MCB thats tripping not an RCD.Giz can you confirm this to enable our diagnosis to continue.

[BRIGHT SPARK]

Gizmo...........can you read all the info on the offending breaker and post it.this will tell me and Fly whats going on.

[Gizmonster]

All of the breakers are single block with switches on.

However, the offending breaker is twice the width of all the others (it's the only one that's twice the width of all the others) and has what appears to be a yellow push button on it.
It has the following written on it:
RCD
80A
30mA
wrs80/2

Underneath it, someone has placed a green sticker with, "Circuits protected by RCD" printed on it.

I never noticed the yellow push button before, but everytime it trips - the switch trips - the yellow button has not been touched and it's not touched to re-set the switch - she just flicks the switch back on.

[BRIGHT SPARK]

You have got a neutral to earth fault somewhere in the circuitry.It is usually in the heating element. At best it may need de fluffing..it does build up over time. If you have done all the checks I suggested then your only choice left is to pay an appliance engineer to fix it.Get a price, do your sums and make a decision to repair or renew. Your circuits are not being overloaded,its the RCD thats tripping.This device detects earth leakage faults and its the only device in your distribution board thats designed to save your life

[Gizmonster]

Well I think (touch wood) the problem is sorted - thanks for all the replies.

When it first started tripping out, her son's friend changed the complete cable, as we thought that might have been the problem.

I took the top off the dryer yesterday to check the condition of the connections, where the lead joins into the dryer - and lo and behold the neutral cable was just hanging there - the screw in the junction box hadn't been tightened up properly.

I made new connections and so far, it hasn't tripped.

I would have thought though, that if the neutral wasn't in properly, the dryer wouldn't have worked at all - no circuit = no power ...... obviously not though. How would a faulty neutral connection cause an earth leakage?

Anyway it's sorted now - that's the main thing.

Thanks again for all the replies.

[BRIGHT SPARK]

Current would be back feeding to the neutral in the dryer possibly from an inductive load , i.e. a motor circuit or a fluorescent ballast.It then transfered to the earth.(via the fault).Because some of the current was now leaking to earth the RCD would detect an imballance within its torroid and hey presto it trips.....usually at about 25 milli amps and at around 18 milli seconds. Test it monthly and get it meter tested yearly...it may save your life one day!!! P.S have a good christmas with the money you've saved