Adding extra sockets to existing ring mains on ground floor

[AndyPRK]

Need to check if there is actually ring continuity first.
It maybe that the ring us broken and its been downgraded or maybe it's just two radials as intended.

Doesn't sound like its worth changing due to small load on circuit.

 

[JohnW2]

Need to check if there is actually ring continuity first. It maybe that the ring us broken and its been downgraded or maybe it's just two radials as intended.

All true - that's why I said 'unless there is a good reason why its 20A'.

Doesn't sound like its worth changing due to small load on circuit.

Again, very probably true - albeit all the OP has told us about loading seems to be that 'all the sockets will not be used at once'. 20A for six double sockets (i.e. 12 'outlets') is not really all that much.

Kind Regards, John

 

[Mikefromlondon]

I upgraded the consumer unit which used to be the old metal box made by MK and had the wire fuses that you pull out .I also renewed part of the wiring which appeared too old and I meggered all the wiring in the house for any weakness in insulation, and also checked all earth resistances as per regs, (16th edition) and repalced any that showed leakage or whwre I had any doubt and cables that looked chewed or otherwise, including one that actually was damaged by a nail!

I did not wire those extra sockets because I thought I could do that any time in future if need be as under the floor there is a full access as I have a full size CELLAR, so i don't even need to rip of floor boards, I purposely chose 20A Circuit breaker. I do not intend any occupiers to start using 3kw electric heaters everywhere and I am paying the bills! much rather the MCB's trip and I know what the occupiers are up to.

Kitchen has its own separate ring mains circuit, and also a seperate cooker circuit.

In addition to this, the DNO wrote to me, wanting to change my electric meter as they suspected something was up, I had that house empty for many years and since the bills for the whole year were less than £40, they suspected something was up, so changed the meter, just then I bought a double pole 100A isolator and asked the DNO to wire the meter output tails to this isolator as I was going to renew the CU in near future, so this isolator came in very handy when i had to change the CU as did not need to call them to remove the service fuse while I changed the old CU to New.

It is just that i wanted to be 100% sure that what I am proposing to do is going to meet the latest regs, as I haven't done any installation work for anyone for now nearly 15 years, I wasn't sure if things may have changed since the 16th edition, I know bathroom earthing is no longer required and use of RCD is now comulsory, luckily I have fitted an RCD on my installation, but I need to seperate it from the lighting circuit, my CU does not have a split bus bar, infact I had to islolate the cooker circuit from the RCD as it kept tripping even on a brand new cooker (oven) due to leakage within elements. I need to do the same for lighting circuit or provide seperate RCD for lighting circuit. Having one common RCD for the entire power means the whole house loses power including lights when it trips.

(The thing about electric ovens is that I had to bypass the RCD to allow the elments to dry of any moisture, after that they would be ok for a few weeks and then start tripping off again as the oven is not in regular use, so it became a nuisance, every time someone wanted to bake something after a month or so, the RCD would trip.)

 

[JohnW2]

... as under the floor there is a full access as I have a full size CELLAR, so i don't even need to rip of floor boards,

That's a great situation to be in - I have exactly the same here - all 'underfloor' ground floor wiring is instantly accessible, just by walking down the cellar stairs!

I purposely chose 20A Circuit breaker. I do not intend any occupiers to start using 3kw electric heaters everywhere and I am paying the bills! much rather the MCB's trip and I know what the occupiers are up to.

Ah, I see - mind you, a B20 MCB would allow them to use about 5.4 kW indefinitely, and around 7k W for an hour or so, without anything tripping!

Kind Regards, John

 

[AndyPRK]

RCBO's maybe your answer to seperate RCD protection for the lights.

 

[Mikefromlondon]

RCBO's maybe your answer to seperate RCD protection for the lights.

I must admit it did not occur to me to use an RCBO for the cooker, as well as for the lights, that would have solved the problem of splitting the bus bar, fortunately on my Wylex 12 way consumer unit there were two seperate Neuteral bars, that did it for me and I just had to bend a live rail tab so that the MCB received its live directly from the unprotected but through the 100Amp mains isolating switch, using a 10mm short length of insulated wire link instead of screwing it to the protected live tab of the bus bar, it was just a question of bending the tab downwards and heat shrink sleeved it.


As my lighting circuits are still on a common protected circuit due to the single bus bar, I will upgrade to RCBO's each of my lighting circuits , when I rewired part of the house, I split lighting ring circuits from 2 to 5 and created a seperate circuits for lower and upper pasage and separte for extended kitchen, and sperate for garden lighting. They are all at 5A
and as for my cellar lighting where the CU is I have a separate circuit such that in the event of other circuit overloading, the celler light should still be available, but a tripped RCD would make that useless as well, so definitely an RCBO will resolve this issue. Thanks.

I am not sure if they do a 5A RCBO with 30mA trip current, and are they a great deal more expensive than the RCDs?
thanks for the good idea, I will bear that in mind for next time. thumbs up.

 

[AndyPRK]

Yes they do 6A 30mA RCBO's. I think they retail around £30 each.

Make sure you get the right style for the board. (post a pic if u need help)



One configuration on the wylex is to put the RCD near the middle and then RCBO's on the right hand side. (so not connected through the RCD)

 

[john4703]

Looking at the diagram, and if there is no reason why the MCB is rated at only 20A, it would be possible to have one junction box in an accessible position right next to the consumer unit and add the extra two sockets so they are on the same ring as the others. (I just wonder why anyone would fit a 20A MCB to a ring unless the cable has to be downrated at some point in its run)

 

[AndyPRK]

The op doesn't want lots of heaters plugged in and so fitted the 20a

 

[Mikefromlondon]

Looking at the diagram, and if there is no reason why the MCB is rated at only 20A, it would be possible to have one junction box in an accessible position right next to the consumer unit and add the extra two sockets so they are on the same ring as the others. (I just wonder why anyone would fit a 20A MCB to a ring unless the cable has to be downrated at some point in its run)

It was a personal choice rather than the 32Amps allowed on a ring circuit, In my own house I have 5x 5A MCB and 5x 15A MCBs and 2x 20A MBC, I rewired my house where I wanted independent circuits for each room, so I wired them as radial circuits and kitchen and extension as ring, and I never had any nuisance tripping except for during genuine fault conditions, in my bedroom I can run a 3Kw fan heater and still use a 1.2kw hair dryer with no problems. None of my MCBs have tripped on overloading condtions except as I said under a real fault condition.


And thanks Andy for that information. cheers.

 

[Mikefromlondon]

Its all done now, I genuinely thank those with whose positive help I removed any doubt I had regarding any possible changes to the latest regs, and I have also learned a few new things like the use of RCBO where a CU cannot be split up easily for protected circuits. I have been out of touch with latest IEE regs.