Hob nuisance trips and makes RCD buzz!

[AAAMUSEMENTS]

Had 2 nuisance trips since the new CU, thought that it was an issue with the garage circuit until yesterday, when I noticed after the second trip that the RCD was making a buzzing/arcing noise only when the hob is on.

It's literally only 2 years old, a halogen one that is made for John Lewis by one of the big manufacturers (exactly which escapes me at the moment).

The question is, how likely is it that the hob is faulty? It's still in guarantee at the moment, but I don't want to have to haul the damn thing out of the worktop unless it is definitely to blame...

 

[sparkytim]

Hi

Buzzing may indicate RCD getting toward threshold of tripping current.

Have you got a low current reading Clamp meter? i.e. one that will measure

m Amps of leakage.

If so clamp around Meter Tails L+N and measure leakage current of Hob when on with nothing else on.

If approaching 24/25 m Amps then may well be cause of tripping.

If less then that turn on other stuff and see if leakage rises as sometimes it is not just one applience but an accumilation of several leakages that just pushes the RCD over its limit.

To see what its limit is do a Ramp test.

 

[AAAMUSEMENTS]

I have a clamp meter somewhere, but it's not a good one so it probably won't measure leakage.

The RCD buzzes when only the hob MCB is switched to on.

 

[ElectekAir]

The RCD buzzes when only the hob MCB is switched to on.

But is the hob on? if only when you turn on the MCB then it is a wiring prob

 

[AAAMUSEMENTS]

But is the hob on? if only when you turn on the MCB then it is a wiring prob

Sorry yes, it's only when the hob is on.

For info the hob is on it's own dedicated 6mm radial with a 32 amp MCB.

 

[ElectekAir]

Can you remove hob from RCD then run hob for 20min or so on full heat then re-connect to RCD and see what happens.

Used to do this years ago with spiral elements which get moisture in if not used

 

[AAAMUSEMENTS]

Can you remove hob from RCD then run hob for 20min or so on full heat then re-connect to RCD and see what happens.Used to do this years ago with spiral elements which get moisture in if not used

It would mean completely reconfiguring the CU!

To be honest though, if moisture in the elements is the problem, I can't see how the hob could be sold as fit for purpose in this day and age?

 

[the_mouse]

Hi

I had a similar problem, intermittent buzzing and arching turned out the RCD wasn

 

[SPECIAL LOCATION]

Screws all tight in CU?

RCD & MCB screws?

have you tested the RCD?

Did you say you have tested the hob on its own with ALL other MCBs turned off?

:|

If all else fails run an extension lead from Admins shed....

he's got spare sockets there! ; \

 

[AAAMUSEMENTS]

I completely changed the RCD earlier this afternoon.

Everything is tight, but still exactly the same as before.

 

[SPECIAL LOCATION]

I completely changed the RCD earlier this afternoon. Everything is tight, but still exactly the same as before.

Lead to Admins shed is needed then!

Think you've sort of pointed everything back to the Hob????

OR.... just thinking a bit more...

allow for GuinnessGuinness

Have you disconnected the hob & Ins res tested the circuit cable again?

No trapped high res conections between L or N and Earth? :|

 

[AAAMUSEMENTS]

Have you disconnected the hob & Ins res tested the circuit cable again?No trapped high res conections between L or N and Earth? :|

This is what worries me... I extended the existing cooker radial so some of the existing cable run was not inspected at the time...

:Blushing

I don't have the facility to insulation test at the moment... although I might be able to borrow a megger.

Alternatively I suppose I could (temporarily) run a nice new piece of cable straight from the CU to the hob, and see if it still has the same fault?

 

[choccy]

testing during and after new installs or extensions of circuits should be par for the course.

:red card

 

[AAAMUSEMENTS]

testing during and after new installs or extensions of circuits should be par for the course. :red card

Thanks for that, perhaps you could find somewhere where there are the unconverted to preach to? :|

A. 2 years ago was before I joined this usually very helpful, welcoming and non judgemental forum.

B. We tried for a good year to find any electricians who were firstly interested enough to even visit, and then only found ones who wanted to rip us off (a good case in point being the one that insisted that the plastic oil tank down the garden needed to have an earth rod).

Is it any surprise that I eventually did the work myself?

Any other helpful comments very welcome...

 

[leccyman]

Well said :Applaud :Applaud

 

[SPECIAL LOCATION]

This is what worries me... I extended the existing cooker radial so some of the existing cable run was not inspected at the time... :Blushing

I don't have the facility to insulation test at the moment... although I might be able to borrow a megger.Alternatively I suppose I could (temporarily) run a nice new piece of cable straight from the CU to the hob, and see if it still has the same fault?

I think borrowing an 'Ins Res' tester needs to be the priority at the moment..

You need to prove if there are any bad connections, damaged insulation etc..

causing your problems.

how intermittently are the trips..

every time hob is on?

or just occasionally?

:|

 

[choccy]

sorry for my harsh reply bad day, and i wlays wanted to use a red card.O) O)

 

[choccy]

bad spelling day too. ray

 

[AAAMUSEMENTS]

sorry for my harsh reply bad day, and i wlays wanted to use a red card.O) O)

No worries mate. You caught me at a bad time too!



Specs; the trips are very infrequent, in fact only twice - but both times the hob has been the common appliance on at the time.

Strangely the RCD does not seem to be buzzing now when the hob is on, but I need to do more testing with an assistant, in order to find out if the fault only occurs when a certain ring or combination of them are being used. Will report back when I have...

 

[SPECIAL LOCATION]

No worries mate. You caught me at a bad time too!

Specs; the trips are very infrequent, in fact only twice - but both times the hob has been the common appliance on at the time.

Strangely the RCD does not seem to be buzzing now when the hob is on, but I need to do more testing with an assistant, in order to find out if the fault only occurs when a certain ring or combination of them are being used. Will report back when I have...

Sounds like a bit of a slippery sod to pin down there sir!

I wish you well in your investimigations...

and it will be good if you can find anything and put us all out of our misery as to what it is! :|

GuinnessGuinnessGuinnessGuinness