Advice re fuse box

[unphased]

I do domestic all the time. My choice for rewires is generally like this:

50A/40A shower 10mm2 radial (if applicable)

32A cooker circuit 6mm2 radial

32A kitchen ring circuit

20A upstairs sockets 2.5mm2 radial

20A downstairs sockets 2.5mm2 radial

6A upstairs lights radial 1.0mm2 (plus smokes)

6A downstairs lights radial 1.0mm2

6A radial to boiler 1.5mm2

Other circuits as individual requirements.

 

[gavindrummond]

Hi unphased why radials and not ring mains ?

 

[steptoe]

quicker , easier, and less cable.

 

[SLIPSHOD & SLAPDASH]

just want to seperate the circuits, if there is ever a problem with the kitchen ring at least the boile would still work. That was my way of thinking. got plenty of spare ways on the fuse box ---------- Post Auto-Merged at 18:40 ---------- Previous post was made at 18:38 ----------

the customer

It wont if its a N-E fault and the RCD wont reset Another reason why we nearly always fit RCBO's

 

[brummydave]

Hi Nozspark, I thought the same as you, if the load on the circuit is only going to be 3A max why the big mcb on the back of it? I have checked my Grandma's house which was recently done by the council and they have the boiler on a 16A mcb so just assumed that was the way to go???

Think it's a common way of using the 16A mcb that comes in a loaded board. Gives theoretical headroom for an immersion too, although that should really be on its own circuit.

I agree, the boiler should be on a 6A.

 

[SLIPSHOD & SLAPDASH]

When i started the boiler was normally connected to the local lighting circuit. Sometimes via a 'clock' socket

Before anyone asks.......................... Surface Clock Connector

 

[brummydave]

When i started the boiler was normally connected to the local lighting circuit. Sometimes via a 'clock' socketBefore anyone asks.......................... Surface Clock Connector

lol! maybe this will return for boilers with internal clocks!?

 

[SPECIAL LOCATION]

Hi unphased why radials and not ring mains ?

Many older properties have been running happily on radials for donkeys years.....

You have to think.....

why do I want a ring...

Generally because the single cable is too small to carry the expected load..

But if as unphased mentions 20A is ok for most upstairs sockets, then why double up the cables?

HOWEVER...

with the increased amount of insulation bunged in houses and greater de-rating valeus..

a ring on a 20A may even become a requirement..

But that aside..

VERY VERY VERY VERY VERY VERY VERY VERY VERY VERY few houses would draw more than 20A on the upstairs..

or downstairs outlets excluding kitchens & utilities.

There is a fixed mindset among some "electricians" probably a lot who have done 'part p' 5 week intensive course..

that Sockets MUST be on a 32A ring....

Its is the differnece between knowing WHAT to do and WHY you do.....

TBH most pre equiped fuse boxes come with far to many 32A MCB's stuck in them....

Could do with some 20A instead!!!!

 

[brummydave]

Hi Everyone,I am an electrician working on the railway and re-wiring a friends house. Total re-wire. Im using a dual rcd board.

I am happy with my upstairs/downstairs lighting and ring mains and know what way to have them on each rcd.

I just have a few questions regarding:-

I am going to wire the kitchen as a seperate ring main. IS THAT OK FOR ALL THE APPLIANCES ETC??

going to put the boiler on its own mcb, 16A fuse spur connection with 3A fuse. OK??

I've put a single 2.5mm feed outside for a future conservatory to wire a radial circuit say 3 sockets on a 16A (20A?) breaker?

also put a single 2.5mm feed outside for outside sockets for pond equipment/lighting etc to again wire a radial circuit 16A OR 20A??

Feel free to give me any pointers or comments on what I am doing, much appreciated fellow sparks

When circuit planning I tend to do a spreadsheet so that room by room I can list all the appliances. And probable loads as well. Then I use that to work out the best distribution. And sizes of cable and MCBs. Generally a ring main for the kitchen is fine, but best to show calcs.

I use diversity in another column to give a full picture of the installation. Helps with determining if the main fuse needs upgrading to an 80A or 100A too.

Also, I prefer at least three lighting circuits as well. Downstairs rooms, Upstairs rooms, and 'areas'.

Areas includes porch, hall, landing, loft etc. That way if any room goes dark, there's overspilling light from an adjacent area. Plus you can work on circuits in the loft without needing a torch.

Finally, if you're going dual rcd watch the loading on each. Some boards come 63A/80A, others have two 80As. If I were starting from scratch I would use the loaded RCBO 'Curve' boards from Denmans too. Bargain!

HTH

 

[SPECIAL LOCATION]

. Helps with determining if the main fuse needs upgrading to an 80A or 100A too.

Seen a few occasion where e-on specifically downgrade some 100A to 80A..

and on a new build often quote 18.5kW (80A) as the standard max single phase supply available.

:|

 

[brummydave]

Seen a few occasion where e-on specifically downgrade some 100A to 80A..and on a new build often quote 18.5kW (80A) as the standard max single phase supply available.

:|

Blimey. Best get more LEDs in them houses then! And unvented water cylinders so no more electric showers...

I come across a load of 60A installations, specially with porcelain/wood fuseboxes attached.

 

[Zeespark]

Dave, when you take diversity, and the actual tripping current of a BS1361 fuse, you will find you wont have issues running anything found in a modern house.

AndyGuinness

 

[pewter]

I rewired my place and each bedroom is on its own 2.5mm radial.

When the boy is naughty I can shut the power down to his bedroom from consumer unit. I think most parents would love that feature. Computer, tv and stereo all off, and staying off until the children pretend to amend there ways.

I love radials, I think rings suck. I'd rather do a 4mm radial if I need 32amp then a 2.5mm ring. But if I am paying for the cable 2.5mm ring will do as the 4mm can be more than double money.

When I rewired my mums utility rooms I put boiler on its own radial, ext socket on its own radial, ext lighting on its own, fridge freezer on its own radial, sockets on Radial . all on rcbo's .

If I had it my way i would never wire a ring up ever again.

 

[a1]

And run in a radial to a dedicated S/O for the Fridge/Freezer.

If RCBO trips while client on holiday, they won't come back to a freezer full of food that has melted etc.

 

[OnOff]

I rewired my place and each bedroom is on its own 2.5mm radial. When the boy is naughty I can shut the power down to his bedroom from consumer unit. I think most parents would love that feature. Computer, tv and stereo all off, and staying off until the children pretend to amend there ways.

I love radials, I think rings suck. I'd rather do a 4mm radial if I need 32amp then a 2.5mm ring. But if I am paying for the cable 2.5mm ring will do as the 4mm can be more than double money.

When I rewired my mums utility rooms I put boiler on its own radial, ext socket on its own radial, ext lighting on its own, fridge freezer on its own radial, sockets on Radial . all on rcbo's .

If I had it my way i would never wire a ring up ever again.

Have I mistakenly clicked on www.talk.electricianforum.fr ? Another thing "I've got a problem with my RADIAL" doesn't sound half so funny..........

(Just to add though, I like the idea of radials too for all the reasons above. Though I reckon with some of the rubbish, IMO, designer sockets (V***x) you would struggle to get 2 x 4mm in them!)

 

[pewter]

'Wire up my ring' sounds worse.

I have never had a problem with 2x 4mm in socket terminals , easier to handle then 3x2.5mm IMO . Would struggle to get 3x4mm in a socket though. Cost is big downer, when I last went to pay for some it was

 

[Zeespark]

Pewter, remember that 4mm 6242Y only has a 1.5mm CPC, so you will need to consider its length when designing the circuit for EFLI purposes.

AndyGuinness

 

[andy_spark]

I rewired my place and each bedroom is on its own 2.5mm radial. When the boy is naughty I can shut the power down to his bedroom from consumer unit. I think most parents would love that feature. Computer, tv and stereo all off, and staying off until the children pretend to amend there ways.

Genius. I wish I had thought about that, I didn't have any children when I rewired my house!:worship

 

[steptoe]

my big issue is SP RCBOs

waste of time and space IMHO

Id rather half my house actually turned off in the event of a fault then only one circuit stopped working but still remained potentially dangerous,

plus the fact that under certain fault conditions using SP RCBOs you get a daisy chain where every RCBO will trip out anyway, so from that point of view they are actually less compliant.