Which, thinking about it, still wouldn't tell me anything other than my mains voltage. I need a drink. ;-D
16A MCB trips when tumble dryer is on
- Thread starter Jimbo
- Start date
Which, thinking about it, still wouldn't tell me anything other than my mains voltage. I need a drink. ;-D
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Even if unintentional, what you sugegsted was not as silly as you suggest. As I recently wrote, IF you measured the pd between L-in and L-out of the MCB (I also said with neutral, but that would not apply to a single-pole MCB!!), if current is flowing through the MCB, you will see a very small pd due to that current flowing through the (very small) internal impedance of the MCB. As I said, it would be a very small voltage - but it should be 'measurable', and any pd between those terminals would mean that current was flowing through it.
However, particularly given that it's Friday evening (and, co-incidentally, my birthday
), please do feel free to have that drink!!Kind Regards, John
Many happy returns, John.
Current drawn measured with a clamp meter is the next thing to check. I've had the insides of sockets etc. burnt out and tracking over causing MCBs to trip after a while. There is usually a burning smell with it though.
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What make of MCB? Was the new one actually new, or one which had been obtained some time ago?
Yes, as I said, a 'leakage' current great enough to produce the observed effects (probably well over 10A, presumably 'continuous') would almost have 'shown itself' - by smell, smoke, flames or whatever!
I would doubt that the OP has a clamp meter - but, as I said, detecting any measurable voltage across the MCB (with no intentional load on the circuit) would indicate some 'unexpected' current flowing!
Kind Regards, John
It might well be tight even if the busbar pring has missed the cage terminal. Het generated can be conducted into the MCB and operate the thermal element.
Thats my second theory, my first was as per flameport.... devices affected under the great 2010 MCB fiasco
True - but, if that were the case, to explain the OP's experience, the same error would have had to have been made when installing the replacement MCB - which still tripped.
Kind Regards, John
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I would be looking at the tumble drier taking more than rated current. I would guess old MCB was stuck, but once it tripped once then it worked as it should. A 13A fuse will take a massive overload, I have seen many a welding machine tripping a 16A MCB but not blowing the 13A fuse.
Yes theory you could measure the voltage across a MCB to work out current, but problem is we don't have a conversion chart to tell us what voltage relates to what current so it's the clamp on meter.
One can only guess, but a tungsten wire heater where the wires have some shorted coils could in theroy draw more than rated current. May be this is why some tumble driers have gone on fire? Maybe this is the answer to all those house fires, it was not build up of fluff but shorted coils on the heater? The other device which could be used is the energy meter, mine has amps and watts and a red lamp which can be set to show overload.
But with all that has been said, I would plum for the tumbler drier at fault rather than the installation.
Yes theory you could measure the voltage across a MCB to work out current, but problem is we don't have a conversion chart to tell us what voltage relates to what current so it's the clamp on meter.
One can only guess, but a tungsten wire heater where the wires have some shorted coils could in theroy draw more than rated current. May be this is why some tumble driers have gone on fire? Maybe this is the answer to all those house fires, it was not build up of fluff but shorted coils on the heater? The other device which could be used is the energy meter, mine has amps and watts and a red lamp which can be set to show overload.
But with all that has been said, I would plum for the tumbler drier at fault rather than the installation.
Most of those heaters run red hot if there is no forced air flow through the coils.
It could be the motor in the tumble drier has suffered wear and tear causing the in rush current when it starts / reverses to become higher and / or longer duration. This could happen if the motor is not able to reach normal speed as quickly as it did when new.
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I would agree, however my point is likely it is the drier rather than installation. My energy meter has a max amps setting and run amps setting so it would be a simple test to plug it in. I would be happier using the clamp on in case the excess amps damaged my plug in energy meter, but the test is easy and the equipment is cheap, so I would likely watch it rather than walk away, but the red over current LED on the energy meter will soon show if a real over load or not even without reading what the digital display shows.
On the contrary, if there is a manufacturing issue now is when you would expect to find it.
I'd try to measure the current it's taking. One option is a clamp meter. An alternative is to turn off everything else in the house and see how fast the meter goes.
Although that is all true, I don't think it could be an explanation for the MCB tripping after the dryer had been running for 20 mins.
Kind Regards, John
Hi folks, OP here.
I've been through the garage wiring looking at all junctions boxes and sockets. Everything is still nice and clean. No scorch marks, no insect or water ingress.
To answer a few queries regarding the MCB, dryer etc.:
I remembered I have a plug-in electricity meter* which shows volts, amps and watts. However typically we've just finished doing all the washing from our holiday so have nothing to put in there right now I ran it empty ("cool-down cycle") and it drew just under 2.3Kw at max - average was about 2.2kW.
If the dryer draws more than the rating sticker states, does this mean it's faulty?
* Mildly funny story: couldn't find the meter anywhere, moved a great load of timber that's waiting to be made into a large shed out of the way of one of my filing cabinets, took ages to move it all and damn thing wasn't in there. Moved all the timber back, turned round and the meter was just sitting there on the shelf behind me
I've been through the garage wiring looking at all junctions boxes and sockets. Everything is still nice and clean. No scorch marks, no insect or water ingress.
To answer a few queries regarding the MCB, dryer etc.:
- The garage CU is MK and the MCBs are MK Sentries. A brand new replacement MCB tripped just like the last one so highly unlikely to be an MCB fault.
- The dryer is just a few weeks old. It was one of the whirlpool £59 replacements because my old one was one of the "it might catch fire but it's not really our problem even though we built it" types. It ran fine for years without tripping, then started to trip so I just forked out for a new dryer. The rating sticker on the back says 2.2 - 2.6 kW.
I remembered I have a plug-in electricity meter* which shows volts, amps and watts. However typically we've just finished doing all the washing from our holiday so have nothing to put in there right now
I ran it empty ("cool-down cycle") and it drew just under 2.3Kw at max - average was about 2.2kW.If the dryer draws more than the rating sticker states, does this mean it's faulty?
* Mildly funny story: couldn't find the meter anywhere, moved a great load of timber that's waiting to be made into a large shed out of the way of one of my filing cabinets, took ages to move it all and damn thing wasn't in there. Moved all the timber back, turned round and the meter was just sitting there on the shelf behind me
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