Professional assessment of DIY work - but was he correct?

[luckyNot]

Hi,

I am a DIY-er with training in domestic installation - I am not certified etc. My house has a modern consumer unit with RCDs and MCBs. I have done minor changes to some existing circuits.

I recently had an Electrician in to re-wire my kitchen - I believe that under current regs (England) I cannot do kitchen work, and I want the work certified.

The electrician has said he wants to put a new board in to run the new kitchen circuit from. I agreed the new circuit was the right way to go. But it was the reason for the new board that bothered me which was that he could not be sure of the earthing on the current setup.. He based this on the following observation:

A downstairs circuit (radial, not ring) feeds several sockets, the MCB is 6 amp (I did not fit this, but I think it was done to avoid risk of running larger current through old wiring, not all of which has been replaced - most I have verified as 2.5mm however).
Plugging in anything powerful (e.g. hoover) trips this as you would expect. Nonetheless the circuit runs TV,Fridge Freezer and coffee machine without issue. This, the electrician said, was a sure sign of an earth fault because the circuit should be tripping constantly and so it was very unsafe.:confused5:

I disagree with this for 3 reasons:
1. the circuit cannot damage the wires because the MCB is so low
2. the circuit has an RCD so it is no more dangerous than any other
3. earth has nothing to do with overloading a circuit and will only come in to play under fault conditions

Please can someone correct me because I am now worried that I misunderstood what I have been taught and potentially have done minor changes that are not as safe as I thought

Thanks

 

[Marvo]

The laymans answer is find yourself another electrician who actually bases his assertions on test results rather than guesswork.

The more technical answer is that an RCD will trip if there's even a very small esarth fault (usually 25-30mA) so if the MCB is tripping andf the RCD isn't then, assuming everything is functioning as it should, it's an overload fault, not an earth fault.

Regardless of all this it's no reason to replace the existing CU if there's enough room for the additional circuits.

Also, even a 2.5mm radial can be protected at 20A unless the cable is run in thick insulation or some other weird installation method. The age of the cable makes zero difference as long as the circuit tests fine and nothing is spurred off on a smaller sized cable without its own appropriate fusing.

 

[telectrix]

asa marvo says. you need to consult an electrician that talks out of his mouth and not his arse. you do have some issues with your installation, but it needs a professional spark to investigate, not a donkey.

 

[Octopus]

Post your location and one of us may not be far away if you want a 2nd opinion

 

[Spoon]

Post your location and one of us may not be far away if you want a 2nd opinion

The OP's status states 'Berks' Not sure if that is referring to a location or just the people living down south

 

[telectrix]

The OP's status states 'Berks' Not sure if that is referring to a location or just the people living down south

love it !. the north rules, UK.

 

[Guest77]

The north is 20 years behind the south na na na na na

 

[Leesparkykent]

I heard one pound in every five earned in the southeast is used to fund the rest of the country :blush2:

 

[Octopus]

I heard one pound in every five earned in the southeast is used to fund the rest of the country :blush2:

That's about right and don't forget that the Scots get the 2nd largest slice only beaten by NI

 

[luckyNot]

I like this forum

Firstly, sorry for the delay in responding, I have been away on holiday.

Secondly, thank you for the quick and helpful responses I was beginning to think I had misunderstood a lot..

Thirdly, 'Berks' is Berkshire and my location in near J12 of the M4. If this is a location that you would consider working and particularly if you could do a first stage kitchen install next week (4 sockets plus cooker, hob, extractor fan), then please leave your details on this thread asap

 

[Spoon]

Thirdly, 'Berks' is Berkshire and my location in near J12 of the M4. If this is a location that you would consider working and particularly if you could do a first stage kitchen install next week (4 sockets plus cooker, hob, extractor fan), then please leave your details on this thread asap

Hi mate. We have a Electricians Unite - Jobs In Your Area section. Try putting what you need doing in a post in that section. You might get more response.