# TRIPPING !

D

#### DAJ

I have just installed a complete new kitchen including double fan oven (5.4kw), hob (6.4kw), griddle (1.4kw), steam oven (1.5kw), plate warmer (1kw), microwave (.9kw), fridge and freezer.

ONE. 6m of 10mm cable run from a 40 amp RCBO (at the moment) in the CU to a 60 amp 3 terminal junction box. From the junction box I have a further 5m of 10mm cable running to a 45amp cooker switch and socket. The switch operates the double oven via 6mm cable and the socket has the microwave plugged into it (via a 13amp fused plug). Also wired into the junction box, is the hob via the supplied cable (six core heatproof flex).

TWO. The steam oven, plate warmer, fridge and freezer are wired in a 32 amp (RCBO) ring each fed from a 13 amp fused spur.

THREE. The griddle, gas hob ignition, waterproof TV (12v DC via transformer) and 3 double gang wall sockets are also wired in a 32 amp (RCBO) ring.

I have completed all of the wiring, nothing grouped, all clipped etc.

I have fitted and wired the double oven (not the hob), BUT! When the oven reaches about 180 degrees, the RCBO trips. In addition, when the grill is turned on, the RCBO trips after about 2-3 minutes. I can only assume that the issue is the length of cable used as I calculate that the oven is 23.48 amps! As the total amps will equate to 51.30 when the hob is wired too, would a 50 amp RCBO be OK to replace the 40 amp RCBO and would it resolve the tripping problem?

THANKS!

#### riveralt

If you put up the schedule of test results here we may be able to give you a hand.

#### sparkticus

I can only assume that the issue is the length of cable used as I calculate that the oven is 23.48 amps!

Please can you expand on the point above? Why do you suspect the length of cable is causing the disconnection (trip) ?

An RCBO can disconnect for overloads, faults and earth leakage. From what you say, it does not seem to be related to overload since the hob is not connected. So we are left with a fault between phase-neutral or a fault between phase-earth or lower level earth leakage. (possible fault between neutral-earth too) These faults could be in the wiring or the oven.

Are you an electrician or do you have electrical knowledge to a competent level? (by competent I mean did you complete the certification process and do you have access to appropriate test equipment)
Did you install the wiring and consumer unit?

#### EFLImpudence

Also
... hob (6.4kw)...
...the hob via the supplied cable (six core heatproof flex)...
...gas hob ignition...

#### sparkticus

would a 50 amp RCBO be OK to replace the 40 amp RCBO and would it resolve the tripping problem?

You need to take an evidence based approach. You already know (if I have understood your post correctly) that you are currently NOT overloading the RCBO (the oven current should be significantly below the RCBO rating)

Before you change anything you need to diagnose the problem first then make an appropriate change.

Oh dear me.

#### sparkticus

Oh dear me.

Apparently without any glue

#### riveralt

would a 50 amp RCBO be OK to replace the 40 amp RCBO and would it resolve the tripping problem?
You need to take an evidence based approach. You already know (if I have understood your post correctly) that you are currently NOT overloading the RCBO (the oven current should be significantly below the RCBO rating)

Before you change anything you need to diagnose the problem first then make an appropriate change.

Sparkicus, its worthwhile looking at this jokers previous posts - particulalry his views on his competency and how he sees no merit in Part P - when in reality he is the very reason for Part P being introduced.
Having been advised to get an electrician in he has gone ahead and installed everything 'competently' but now comes here to seek help to get him out of the mess he has got himself into....

I will not hold my breath for the Schedule of Test results..

#### sparkticus

Sparkicus, its worthwhile looking at this jokers previous posts - particulalry his views on his competency and how he sees no merit in Part P - when in reality he is the very reason for Part P being introduced.
Having been advised to get an electrician in he has gone ahead and installed everything 'competently' but now comes here to seek help to get him out of the mess he has got himself into....

I will not hold my breath for the Schedule of Test results..

I just read it all and oh dear!! I retrained as an electrician about 20 years ago. I was an electronics engineer with about 15 years experience at the time. Most of my experience was in the semiconductor industry working on LED and Laser diode parametric test equipment design. I arrogantly thought that retraining as an electrician would be almost insignificant because I was a high flying electronics engineer. Did I eat my words during the training which included a BTEC in electrical engineering and the more practical City & Guilds. It was much more complex & challenging than I had imagined and it was not all about the regs. The OP seems to think that he can become a "competent person" and self certify in about three weeks. He obviously has not experienced the registration process for the competent persons scheme. The only thing three weeks will do for him is cause him realise that he would need a lot more time.

He clearly has made mistakes in not designing the kitchen circuits well (almost 12 KW on a single circuit when he could have discriminated with separate hob/oven) He appears to lack the ability to think logically with regard to technical challenges and seems a little confused about cable length somehow being the cause of the RCBO trip.

D

#### DAJ

I just read it all and oh dear!! I retrained as an electrician about 20 years ago. I was an electronics engineer with about 15 years experience at the time. Most of my experience was in the semiconductor industry working on LED and Laser diode parametric test equipment design. I arrogantly thought that retraining as an electrician would be almost insignificant because I was a high flying electronics engineer. Did I eat my words during the training which included a BTEC in electrical engineering and the more practical City & Guilds. It was much more complex & challenging than I had imagined and it was not all about the regs. The OP seems to think that he can become a "competent person" and self certify in about three weeks. He obviously has not experienced the registration process for the competent persons scheme. The only thing three weeks will do for him is cause him realise that he would need a lot more time.
He clearly has made mistakes in not designing the kitchen circuits well (almost 12 KW on a single circuit when he could have discriminated with separate hob/oven) He appears to lack the ability to think logically with regard to technical challenges and seems a little confused about cable length somehow being the cause of the RCBO trip.

HOW BORING...

Hi everybody, thanks for all your "help". I've fixed it now. I was right, the 10mm cable WAS too long! I've shortened it to about 2m- It means having the hob and oven in the broom cupboard with the CU but at least the oven works now and I'm able to make toast too as the 2.5mm glows red in the dark when I turn the cold tap on! There was a strange humming noise coming from the 40 amp RCBO so I've replaced it with a 60 amp one and cut off the earth connection (and it still works!). I bought a whole pad of Part P certs on ebay, can anyone help me fill one in please as I need some sort of number?

This is a fantastic web site, so much help and all free of charge - that must be upsetting for all the old farts who've bothered getting qualifications. I find it just as simple to make it up as you go along, it's more fun - just difficult making a claim when the fires start!

I see you've been helping people for many, many - well - em, weeks Spiticus (joined in May) - well done on your BTEC mate, your mummmy must be very proud of you! Did you obtain it from OU?

Oh - before I go - I'm fitting a new gas boiler next week, can anyone tell me what size plastic pipe to use?

D

#### DAJ

GET A LIFE GUYS !

#### sparkticus

Daj, you have no choice but make it up as you go along since you don't have the basic knowledge to design. But never fear, there is help out there for you! You just need to admit your difficulties then enrol for appropriate training.

#### RF Lighting

God you're hilarious.

D

#### DAJ

Daj, you have no choice but make it up as you go along since you don't have the basic knowledge to design. But never fear, there is help out there for you! You just need to admit your difficulties then enrol for appropriate training.

Little do you know Pal - I'm saying no more as I don't need to explain myself to those that have little or no life!

D

#### DAJ

God you're hilarious.

RF- You're a star mate! You've made my day, THANKS!

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