Socket or spur?

[fozzy9876]

So we have been careful to run one appliance at a time. However, after doing 3 loads of washing / drying today the 13amp FCU failed and tripped the consumer unit. Can it be replaced by 20Amp double pole. Or best for someone qualified to look into it?

 

[Harry Bloomfield]

I couldnt remove the fuse out of the old FCU. Hacking away with a screwdriver the plastic looks to have melted, so presumably it has ruptured.

That may, or may not suggest the fuse has ruptured - what it suggests, is that the fuse has suffered overload, for a long enough period for it to overheat, and overheat the FCU. Long enough to melt the two to jamming.

So we have been careful to run one appliance at a time. However, after doing 3 loads of washing / drying today the 13amp FCU failed and tripped the consumer unit. Can it be replaced by 20Amp double pole. Or best for someone qualified to look into it?

No you cannot replace it with a 20amp double-pole, or at least not without investigating the circuit, and determining why a 13amp fuse was thought necessary, to limit the current. The overloaded fuse above, might well be a second issue, perhaps not directly connected to your primary issue of the power cutting off randomly....

Do you know which circuit the double socket and FCU are supplied from, at the consumer unit? Could you post a photo of it, the double socket, the FCU, and anything else you think relevant?

 

[EFLImpudence]

- what it suggests, is that the fuse has suffered overload, for a long enough period for it to overheat, and overheat the FCU. Long enough to melt the two to jamming.

Surely that is what the fuse is supposed to prevent.

Is it not more likely to have been caused by a loose connection; probably a loose fuse holder?

 

[Harry Bloomfield]

Surely that is what the fuse is supposed to prevent.

Is it not more likely to have been caused by a loose connection; probably a loose fuse holder?

Possibly, but - as you ought to know.... The mode of operation of a fuse, and fuse wire is - when they pass more than their rated current, to get warm, and/or hot, depending on the level of over current. A 13 amp fuse, simply doesn't go o/c at 13.1 amp. Consistently overload a fuse, and the heat from the fuse, will eventually damage the fuse-holder.

 

[securespark]

I'm not sure why the CU is tripping, and why you need to switch off/on at the FCU to restore power.

 

[Harry Bloomfield]

I'm not sure why the CU is tripping, and why you need to switch off/on at the FCU to restore power.

We will never know the cause, unless and until the OP responds to the questions I posed in my final para of post #17

His photo in #1, might suggest the FCU is possibly supplied from a 32amp ring circuit, but everything else, including that, really is just guess work.

 

[fozzy9876]

Picture of the double socket, FCU and consumer board. Not sure which circuit it's on, but it trips the switch to left which is down.

Thanks

 

[Harry Bloomfield]

Picture of the double socket, FCU and consumer board. Not sure which circuit it's on, but it trips the switch to left which is down.

Progress

The one which is down, is an RCD. Which means either the live or the neutral, on any one of those circuits to the right of the RCD, has a leak to earth of greater than 30mA. The cause of which, could be absolutely anything fed via that RCD - the wiring buried in the walls, the accessories (sockets, switches, ceiling roses etc.), or anything plugged in. It could even be an accumulation of leakages, of several sources. So likely you can look forward to some fun, tracing the cause...

Your best way forward, is to plug a low wattage table light, or similar, into that double socket, turned on, into which you plug the drier into, and simply work out when the light (and it's socket) goes off - and decide what you were switching on, or off at the same instant it went off.

I think you are suggesting it only trips, when you are using the washer? Is it an older washer? If so, it might be due to carbon dust, from the motor brushes, causing leakage to earth - a fairly quick and easy fix, if that is the cause.

 

[securespark]

It's a new washing machine.

Whether it is new new or new to the OP we will wait to find out.

 

[fozzy9876]

Thanks. Yes the washer was brand new, bought December last year. It was the tumble dryer which was on when it tripped this time!

 

[EFLImpudence]

Possibly, but - as you ought to know....

Yes, I do. That's why I wrote what I did.

The mode of operation of a fuse, and fuse wire is - when they pass more than their rated current, to get warm, and/or hot, depending on the level of over current. A 13 amp fuse, simply doesn't go o/c at 13.1 amp. Consistently overload a fuse, and the heat from the fuse, will eventually damage the fuse-holder.

So - you are saying that FCUs are not fit for purpose.

 

[Harry Bloomfield]

Thanks. Yes the washer was brand new, bought December last year. It was the tumble dryer which was on when it tripped this time!

OK, that suggests it is either - neither of the machines causing the trip, or both of them. Let us know if a trip ever happens, when neither machine is in use, or plugged in. Leave the test light plugged in, so you know when it has tripped.

Just so you know how the RCD works, what it does....

It monitors and compares the current flow through both L and N. If there is a difference of 30mA, or more, it assumes the current has found an alternative route of escape to earth, perhaps via you, so it disconnects the supply.

Simply turning things off, leaves the N connected, so a N to E fault, or leakage, due to a small difference in voltage between the two, can still trip an RCD. Hence, the need to unplug, when trying to trace the cause of the problem.