Rings or Radials ....

[Octopus]

Just started on a complete refurbishment / extension on a 3 bedroom property which is having a complete rewire.

I'm not keen on Dual RCD boards, nor trying to have as few circuits as possible ....

So when it comes to the socket circuits I was thinking of:

Radial 20A for hall, lounge and dining room
Ring 32A for kitchen
Radial 20A for upstairs

Anyone like to comment?


PS the plumber was asking me today why I was installing 35 mm boxes - he seemed to think 25 were always best!

 

[Pete999]

Just started on a complete refurbishment / extension on a 3 bedroom property which is having a complete rewire.

I'm not keen on Dual RCD boards, nor trying to have as few circuits as possible ....

So when it comes to the socket circuits I was thinking of:

Radial 20A for hall, lounge and dining room
Ring 32A for kitchen
Radial 20A for upstairs

Anyone like to comment?


PS the plumber was asking me today why I was installing 35 mm boxes - he seemed to think 25 were always best!

If you don't like dual RCD boards do you intend using RCBOs? I would imagine it's your choice what size back boxes you use, why is the Plumber sticking his oar in? sometimes the deeper the back box the better. Maybe in questioning your choice of back boxes, he was gleaning information from you, ask him why he is using the size of pipe he has chosen, just for a laugh.

 

[Spoon]

If they have the money then put one radial per bedroom, then when any of the kids wont come off the PS4 or Xbox you can just flip the switch to that room..

 

[Ian1981]

Why not a 32 amp radial for the kitchen using 4mm cable then you won’t have any rings?
Depends as well if your using 2.5mm for a 20amp radial that you don’t exceed the maximum zs for the mcb which will be 2.19 ohms for a type B that is 1.75 ohms with rule of thumb and if it’s larger that the recommendations in appendix 15 you may have volt drop issues.
Perhaps 4mm radials for all 3 if you don’t want to install ring finals on 32 amp mcbs reference method permitting.

Ps I only ever use 35mm with things like fused spurs or if I’m fitting flat plate sockets.
It’s true that you’ll probably have more flexibility with 35mm but they you go.
Try asking my gaffer to start fitting bigger than 25mm boxes for sockets on new builds I know what the answer is............

 

[ipf]

Rings......when it suits.
Radials ......when it suits.
So I can't see any problem with your plans.

I, generally, can't see any problem with 25's. You can always sink them in a bit further, after all.

 

[suffolkspark]

if your doing a 20a radial upstairs you'll probably have to wire it in the floor and not the loft (ref method 101 may be an issue)

 

[Octopus]

If you don't like dual RCD boards do you intend using RCBOs?

I stopped fitting dual RCD boards when the AMD3 rules came along - RCBO boards everytime since then.

 

[sam400]

Don't install ring finals myself. Always 35mm boxes though

 

[7029 dave]

IMO, if you are rewiring RFC always, as for the split board, up to you if the client will spend the money RCBO's, I like that option anyway. 35mm boxes more bashing so what.

 

[willy fixit]

Always check what style accessories they're thinking of then there no surprise when they want flat plate shiny outlets squeezed into the 25mm boxes - Thank goodness for spacers and a big black permanent marker!

 

[Pete999]

I stopped fitting dual RCD boards when the AMD3 rules came along - RCBO boards everytime since then.

Thanks

 

[Des 56]

I have a very vague memory of using 25 mm boxes
The memory seems to coincide with some numpty coming up with the idea of making flat plate accessories

The scary part is that there were customers who actually liked the monstrosities,it made me realise they were here to stay and the days of the good old 25mm box were history

 

[Ian1981]

I have a very vague memory of using 25 mm boxes
The memory seems to coincide with some numpty coming up with the idea of making flat plate accessories

The scary part is that there were customers who actually liked the monstrosities,it made me realise they were here to stay and the days of the good old 25mm box were history

I believe it was satin himself

 

[Midwest]

I stopped fitting dual RCD boards when the AMD3 rules came along - RCBO boards everytime since then.

I've fitted a few RCBO only, but MK only, errkk!. The rest are somewhat more expensive, unless the client doesn't mind paying more?

 

[Leesparkykent]

35mm as standard here and 47mm for media plates. 25mm on cheap white plastic, rental rewires.

 

[Leesparkykent]

I've fitted a few RCBO only, but MK only, errkk!. The rest are somewhat more expensive, unless the client doesn't mind paying more?

I can get a 10way lewden/control gear board with 8 RCBO's for £99

 

[Octopus]

I fit the Control Gear units - as Lee says - a small premium, for a simpler set up and far easier to fault find when it starts tripping.

 

[Andy78]

I have used the lewden boards too. Seem fine to me.

 

[Toneyz]

I stopped fitting dual RCD boards when the AMD3 rules came along - RCBO boards everytime since then.[
Deleted

 

[Dozer 73]

Only problem with 35mm boxes , not so good on the single skin walls , very easy end up in next room

 

[123]

Only problem with 35mm boxes , not so good on the single skin walls , very easy end up in next room

Are you chasing the walls with a jack hammer or something?

 

[Dozer 73]

Are you chasing the walls with a jack hammer or something?

Of course , why what do you use
Residents aren’t usually too happy with a compressor in their living room though

 

[123]

I fit the Control Gear units - as Lee says - a small premium, for a simpler set up and far easier to fault find when it starts tripping.

What do you fit if it's TT?

 

[123]

Of course , why what do you use
Residents aren’t usually too happy with a compressor in their living room though

Wall Chaser and SDS Chipping Hammer - have yet to burst into the next room with 35mm deep boxes

 

[Dozer 73]

Can’t say I’m an expert on the house bashin so I,ll stand corrected
And probably leave it to the specialists

 

[Octopus]

What do you fit if it's TT?

not had one yet but I'm thinking 100 mA RCD in place of the 100a dp switch

 

[Leesparkykent]

not had one yet but I'm thinking 100 mA RCD in place of the 100a dp switch

Wouldn't be a good idea with them control gear RCBO's due to not being double pole or SPSN. The new wylex compact RCBO's are SPSN I believe.

 

[Ian1981]

deleted

 

[westward10]

Wouldn't be a good idea with them control gear RCBO's due to not being double pole or SPSN. The new wylex compact RCBO's are SPSN I believe.

Does that matter if they are only being used for circuit protection and not isolation with the main double-pole rcd supporting them.

 

[Leesparkykent]

Does that matter if they are only being used for circuit protection and not isolation with the main double-pole rcd supporting them.

well yeah unless you want the whole board tripping in the event of a neutral-earth fault...RCBO trips, as it's solid neutral the neutral isnt disconnected so takes out the upfront time delayed RCD.

 

[Midwest]

I can get a 10way lewden/control gear board with 8 RCBO's for £99

My local wholesaler only stocks MK, Wylex and some Hager stuff, unfortunately.

 

[Midwest]

Are you chasing the walls with a jack hammer or something?

The internal walls on a local residential estate (circa 1985), which I do a fair bit of work on, are made up of three pieces of 12mm plasterboard, stuck to each other

 

[Midwest]

well yeah unless you want the whole board tripping in the event of a neutral-earth fault...RCBO trips, as it's solid neutral the neutral isnt disconnected so takes out the upfront time delayed RCD.

My memory is a bit hazy, but I recall the 18th draft mentioning something about this subject? Guess division of installation would still have to be considered.

 

[stevethesparks]

Tried my fist SBS DP rcbo board this month, and am quite pleased with it. Mine was on a TT system, and I used a time delayed 100mA RCD as the main switch. The install was made easier and looked neat without all the wandering tails and functional earth leads from the rcbo's. Good price and quick delivery.

 

[suffolkspark]

if you've got TT you can fit a full RCBO board and LEAVE the 100A DP switch upfront unchanged.

if you've got a dual RCCB board, that is when you need to change the upfront 100A DP to a 100mA type S.

 

[Adj]

35mm boxes always - but the the dot and dab boys don't half cuss when I don't sink them in.

 

[Leesparkykent]

My local wholesaler only stocks MK, Wylex and some Hager stuff, unfortunately.

Change wholesaler ....I get them from Electric centre. My local branch stopped stocking MK as everyone moaned about them. On the shelf they now keep Hager and Lewden.

 

[sam400]

if you've got TT you can fit a full RCBO board and LEAVE the 100A DP switch upfront unchanged.

if you've got a dual RCCB board, that is when you need to change the upfront 100A DP to a 100mA type S.

What’s the thinking behind this?

Cheers

 

[suffolkspark]

What’s the thinking behind this?

Cheers

In a dual RCCB board you have the brown and blue link leads between the main switch and the RCCB's and neutral bars IF any of these were to come adrift or melt or be nibbled, and come into contact with the metal, then the only protective device is the service head fuse, and on TT you can be pretty sure you wont have a low enough Zs to allow enough current to flow to blow it so it will just sit there live all day long. in this instance the 100mA type s gives those internal link wires fault protection, and also maintains discrimination from your 30mA RCCB's.

With a full RCBO board there are none of these internal links so no need for upfront protection, and as somebody mentioned if you use single pole RCBO's and DO fit an upfront 100mA type S RCCB, you havn't got discrimination as the neutral will be left in circuit if the RCBO trips which could trip the 100mA.

In both instances a gland should be used on the incoming tails.

 

[Toneyz]

The internal walls on a local residential estate (circa 1985), which I do a fair bit of work on, are made up of three pieces of 12mm plasterboard, stuck to each other

I remember those walls nightmare for installing boxes.

 

[stevethesparks]

if you've got TT you can fit a full RCBO board and LEAVE the 100A DP switch upfront unchanged.

if you've got a dual RCCB board, that is when you need to change the upfront 100A DP to a 100mA type S.

Just belt and braces approach as was so cheap

 

[bigspark17]

In a dual RCCB board you have the brown and blue link leads between the main switch and the RCCB's and neutral bars IF any of these were to come adrift or melt or be nibbled, and come into contact with the metal, then the only protective device is the service head fuse, and on TT you can be pretty sure you wont have a low enough Zs to allow enough current to flow to blow it so it will just sit there live all day long. in this instance the 100mA type s gives those internal link wires fault protection, and also maintains discrimination from your 30mA RCCB's.

With a full RCBO board there are none of these internal links so no need for upfront protection, and as somebody mentioned if you use single pole RCBO's and DO fit an upfront 100mA type S RCCB, you havn't got discrimination as the neutral will be left in circuit if the RCBO trips which could trip the 100mA.

In both instances a gland should be used on the incoming tails.

Theres still a tail from main switch to N bar, i will still fit rcd td upfront on TT

 

[suffolkspark]

Theres still a tail from main switch to N bar, i will still fit rcd td upfront on TT

Nothing wrong with that at all as long as your RCBO's are 2 pole.

 

[Dave OCD]

Has anyone ever seen a meter tail or internal link actually become detached and cause a short ? Not only would it have to come out of the terminal/cage clamp it would also have to move considerably. About as much chance of me winning the lottery.

 

[suffolkspark]

Nope, its all overkill like a lot of our regs to be fair

 

[Midwest]

Has anyone ever seen a meter tail or internal link actually become detached and cause a short ? Not only would it have to come out of the terminal/cage clamp it would also have to move considerably. About as much chance of me winning the lottery.

---- happens!

 

[bigspark17]

Nothing wrong with that at all as long as your RCBO's are 2 pole.

Until the cheap sh*t rcbo fails and you have no fault protection on that circuit.

 

[sparksfly]

I have avoided the really cheap RCBOs due to failures in the past incl control gear, I prefer dual RCD with the odd RCBO to keep costs down. I know they are all made to the same BS standard but are all vans made the same !!

 

[Phillip]

Just started on a complete refurbishment / extension on a 3 bedroom property which is having a complete rewire.

I'm not keen on Dual RCD boards, nor trying to have as few circuits as possible ....

So when it comes to the socket circuits I was thinking of:

Radial 20A for hall, lounge and dining room
Ring 32A for kitchen
Radial 20A for upstairs

Anyone like to comment?


PS the plumber was asking me today why I was installing 35 mm boxes - he seemed to think 25 were always best!

 

[Phillip]

Just started on a complete refurbishment / extension on a 3 bedroom property which is having a complete rewire.

I'm not keen on Dual RCD boards, nor trying to have as few circuits as possible ....

So when it comes to the socket circuits I was thinking of:

Radial 20A for hall, lounge and dining room
Ring 32A for kitchen
Radial 20A for upstairs

Anyone like to comment?


PS the plumber was asking me today why I was installing 35 mm boxes - he seemed to think 25 were always best!

Ring up, ring down and ring the kitchen. The cost of a return cable is not worth the mention. As for what back box size, fit the easiest for the job on the day. If the customer decides to have something else fitted later on, which won't fit the box, then you charge according.