AFDD in 18th 2nd Amendment

[UNG]

At risk of feeding the troll

A point brought up in this thread was that expensive AFDDs being mandatory in flats in blocks of 6 floors and over, installation will be cut to the bare bone to save costs, with 1940s/50s levels of scant circuits. They may filter down to all residential installations. But it can be done safely and cheaply...

So let's look at a 3 bed flat on the 6th floor.
1. One final ring with a 32A AFDD. This has no heavy current appliances apart from say a 3kW kettle. Most being TVs and the likes.
2. RCBOs on all other circuits.
3. LED lighting, smoke alarm and bathroom extractor fan has one circuit using 1.00mm cable. 3A RCBO.
4. Heavy kitchen appliances on one circuit. A 4mm cable to a bank of FCUs in the kitchen. 1.5mm cable from FCU to each appliance: w/machine, tumble dryer, dish washer. Appliances hard wired in - safer. 40A RCBO.
5. 6mm cooker cable to the oven and induction hob - no need to be on separate circuits. Both hard wired in. 40A RCBO.

So, four circuits. One AFDD and three RCBOs. 1.00mm and 1.5mm cable used. Cheap and safe.

The same could be for an average British semi. Maybe with two lighting circuits - but two are not required. This gives five circuits. Installation costs are then cut right down.

Please explain how the regs allow this optimistic method of cable and protective device choice
So where in this minimalist installation would you connect the outside lights, the garage, the shed in the garden, the EV chargepoint, the solar PV etc etc

Nuisance tripping? Where? How?
Overloading? Where?

Q1? Is it safe? Yes.
Q2? Is it legal? Yes.
Q3? Does it protect against arcing on sockets? Yes.
Q4? Does it give full RCD protection? Yes.
Q5? Does full overload protection? Yes.
Q5? Does it give full fault protection? Yes.

Q2 proves to some extent that this is trolling when did legal find it's way into an electrical installation when we all work to the recommendations of a non statutory document
With regard to nuisance tripping one RCBO trips and your cooking appliances are taken out could be a bit inconvienent on a Friday evening or a weekend or is it microwave dinners for a few days until the electrician calls to fix the fault

You may not see an argument for it, and more will be on your side because of: we have alwasy done it this way. My point is that as AFDDs are expensive and mandatory with copper cable prices rising as world copper prices rise, these sorts of installations may be coming soon, and be quite common.

Many years ago most installations only had 3 or 4 circuits so your argument isn't necessarily correct in general more circuits are used these days to minimise the inconvience of tripped circuit taking out a large section of the installation

As a side issue, the British are famous for over-sizing cable. 6mm to a hob when 4mm will do it. 1.5mm for lighting when 1.00mm can do it, 2.5 from an FCU to an appliance when 1.5mm can do it, etc.

So where do you get that the British are famous for oversizing cable from and who is it thinks this could it be YOU when maybe it is done from a more cautious point of view at the design stage, electrical installations are always changing and evolving especially within the kitchen with hobs and ovens of various loads from 2Kw upto more than 10Kw a few extra pounds now can potentially save some money in the future when an appliance is changed
With regard to cable how many different cable sizes do you carry in stock or carry to site for the few metres of 1.5mm² from an FCU to an outlet plate needed on a job do you carry a drum of 1.5mm² for this or just use the 2.5mm² you have been using on this and other circuits

 

[John-SJW]

At risk of feeding the troll

Please explain how the regs allow this optimistic method of cable and protective device choice
So where in this minimalist installation would you connect the outside lights, the garage, the shed in the garden, the EV chargepoint, the solar PV etc etc

Q2 proves to some extent that this is trolling when did legal find it's way into an electrical installation when we all work to the recommendations of a non statutory document
With regard to nuisance tripping one RCBO trips and your cooking appliances are taken out could be a bit inconvienent on a Friday evening or a weekend or is it microwave dinners for a few days until the electrician calls to fix the fault

Many years ago most installations only had 3 or 4 circuits so your argument isn't necessarily correct in general more circuits are used these days to minimise the inconvience of tripped circuit taking out a large section of the installation

So where do you get that the British are famous for oversizing cable from and who is it thinks this could it be YOU when maybe it is done from a more cautious point of view at the design stage, electrical installations are always changing and evolving especially within the kitchen with hobs and ovens of various loads from 2Kw upto more than 10Kw a few extra pounds now can potentially save some money in the future when an appliance is changed
With regard to cable how many different cable sizes do you carry in stock or carry to site for the few metres of 1.5mm² from an FCU to an outlet plate needed on a job do you carry a drum of 1.5mm² for this or just use the 2.5mm² you have been using on this and other circuits

Oh I am feeding this troll. Apologies to all.

"Please explain how the regs allow this optimistic method of cable and protective device choice"

Please explain where they do not?

"So where in this minimalist installation would you connect the outside lights, the garage, the shed in the garden, the EV chargepoint, the solar PV etc etc"

None are required. It is a flat needing an AFDD. Sharpen up!

"when did legal find it's way into an electrical installation when we all work to the recommendations of a non statutory document"

The installation is legal and to 18th, inc amendments. That is clear.

"With regard to nuisance tripping"

That installation would not nuisance trip, as it is fitted to regs and tested.

"So where do you get that the British are famous for oversizing cable from"

You only have to look around. Even now, lighting using LEDs is done in 1.5mm in may installations.

 

[nicebutdim]

Tell me where that installation would give problems? All heavy appliance are on their own radial. As are the cooking appliances - a 3kW oven or hob with 13A plugs are not on the ring. The ring will take few heavy current appliances and these used only for very short periods. The installation will be sound indeed with high protection.

I think you may be on about devices that operate on earth leakage.

According to point 4 of your plan, all heavy loads are on a single radial and each appliance fed from a bank of FCUs.

If you consider that to be good design, and in accordance with regulatory requirements, then I don't know what to tell you. I'm an apprentice who rarely works on domestic installations, but find such an idea shocking (no pun intended).

Your clients may be grateful for saving them a few pounds, but that gratitude will seem misplaced if an electrician has to come behind and resolve future problems those clients could never have envisaged. I doubt any electrician called out to diagnose nuisance tripping would be likely to compliment the installation you've outlined above.

 

[UNG]

"Please explain how the regs allow this optimistic method of cable and protective device choice"

Please explain where they do not?

Table 4D5 might explain the issue a 4mm² cable on a 40A RCBO and 6mm² is pushing it

"So where in this minimalist installation would you connect the outside lights, the garage, the shed in the garden, the EV chargepoint, the solar PV etc etc"

None are required. It is a flat needing an AFDD. Sharpen up!

What about a ground floor flat that has an exit to outside and not a communal area or a block of flats with open landings it is possible they may have outside lighting and one block of sheltered accomodation I was at recently had outdoor sockets on the open landings for charging the residents mobility chariots
So maybe it is you that needs to sharpen up

"when did legal find it's way into an electrical installation when we all work to the recommendations of a non statutory document"

The installation is legal and to 18th, inc amendments. That is clear.

You are more than clearly demonstrating a level of ignorance regarding the standing of the regs here

"With regard to nuisance tripping"

That installation would not nuisance trip, as it is fitted to regs and tested.

I cannot find anything in the regs that suggests an installation that is compliant (a liitle clue regarding the previous comment) with the regs prevents nuisance tripping especially when you cannot control what is plugged into socket outlets

"So where do you get that the British are famous for oversizing cable from"

You only have to look around. Even now, lighting using LEDs is done in 1.5mm in may installations.

So you highlight one type of circuit IMO there is little cost saving as when you have a fault you end up having to reconnect all the cables that break when you remove a switch to fault find

 

[John-SJW]

According to point 4 of your plan, all heavy loads are on a single radial and each appliance fed from a bank of FCUs.

If you consider that to be good design, and in accordance with regulatory requirements,

That is good design. All heavy appliances are one circuit. It conforms to the 18th and its amendments.

I have not done this. Sharpen up! Read what I write. I even put bits in bold for clearer understanding. AFDDs are expensive, so what is a cheap minimal installation with rising costs, in a flat requiring as few AFDDs as possible to keep costs as low as possible? It was quite clear.

it may need an SPD, so let us put one of those in. Then the installation has RCBOs/AFDD and SPD. Ultimate protection.

What is this nuisance tripping you keep referring to? It will be fitted to the 18th and amened and tested. With quality parts.

BTW, as aside. A relative has lived in a late 1980s 4 bed detached house with 2 bathrooms for 25 years. It amazed that the CU had one 32A ring, two 6A lighting circuits. One 16A immersion radial and one 6mm cooker circuit. Five circuits. All in MCBs no RCD. I asked "had you had any problems"? He said 'none ever'. This setup was minimal at even that time - even then three rings were being fitted in such large houses. But it all worked for for 35 years. He had a big fridge, washing machine, tumble dryer, dishwasher, the lot, all off one 32A ring. My AFDD minimal proposal design is more comprehensive than this.

Solar panels, inverter, new CU, new circuits, one for garage, new ring for kitchen, all using DP RCBOs, was fitted. Along with solar preheat cylinder using an iBoost. His energy bill over the past two months has been near zero.

 

[nicebutdim]

Sure thing

If you wish to consider a combination of dish washer, fridge, freezer, washing machine, tumble dryer etc on one circuit to be good design, then I see no point in further discussion.

You have access to BS7671:2022 and if you believe the outlined installation (you also state is suitable for a semi-detached property, with the addition of an extra lighting circuit) is compliant, then that's your business and I'll leave you to it.

 

[John-SJW]

Table 4D5 might explain the issue a 4mm² cable on a 40A RCBO and 6mm² is pushing it

4mm cable can take at best around 41A. I meant to write 32A protecting the 4mm cable. A 3kW tumble dryer, washing machine 2.2kW and dishwasher at 1.5kW. All well under 32A when all full on. Depending on cost, it may be cheaper to replace the 4mm cable with a ring supplying the three heavy appliance FCUs.

You have not a clue invenet all sort of future scearios. I am suprosed you [never mention wiring for a nuckear shelter in cae Putin sent over nukes. Read back on what I wrote. The design is all sound and to regs with ultmate protection inc AFDDs. Put 32A RCBO on the 4mm cable (my mistake).

 

[John-SJW]

Sure thing

If you wish to consider a combination of dish washer, fridge, freezer, washing machine, tumble dryer etc on one circuit to be good design, then I see no point in further discussion.

You have access to BS7671:2022 and if you believe the outlined installation (you also state is suitable for a semi-detached property, with the addition of an extra lighting circuit) is compliant, then that's your business and I'll leave you to it.

I said it was for a flat that needed AFDD. Sharpen up. Dishwasher (1.5kW), w/machine (2.2 kW), tumble dryer (3 KW), are all together under 32A, so fine on a radial. Fridge/freezer can go on the ring - they consume 150 watts, even the American style fridges it is only around 250 watts. They do not continuously run as the thermostats cut them out.

The design I outlined, giving full protection to the 18th and amendments is 100% within regs. Sharpen up.

I feel like I am conversing with a confused apprentice still grappling with matters.

 

[westward10]

4mm cable can take at best around 41A. I meant to write 32A protecting the 4mm cable. A 3kW tumble dryer, washing machine 2.2kW and dishwasher at 1.5kW. All well under 32A when all full on. DEpending on cost, it may be cheaper to replace the 4mm cable with a ring supply the three FCUs.

You have not a clue invenet all sort of future scearios. I am suprosed you [never mention wiring for a nuckear shelter in cae Putin sent over nukes. Read back on what I wrote. The design is all sound and to regs with ultmate protection inc AFDDs. Put 32A RCBO on the 4mm cable (my mistake).

And this circuit will satisfy Regulation 531.3.2 (iii).

 

[UNG]

4mm cable can take at best around 41A. I meant to write 32A protecting the 4mm cable. A 3kW tumble dryer, washing machine 2.2kW and dishwasher at 1.5kW. All well under 32A when all full on. DEpending on cost, it may be cheaper to replace the 4mm cable with a ring supply the three FCUs.

Please tell me what regs book and table gives 4mm² T&E as able to carry at best 41A

You have not a clue invenet all sort of future scearios. I am suprosed you [never mention wiring for a nuckear shelter in cae Putin sent over nukes. Read back on what I wrote. The design is all sound and to regs with ultmate protection inc AFDDs. Put 32A RCBO on the 4mm cable (my mistake).

I'm beginning to find your comments a bit condescending and very very stupid while you are trolling for a response and now you are backtracking because you are not even proof reading your replies before posting them

 

[westward10]

Well does it satisfy Regulation 531.3.2(iii).

 

[UNG]

I said it was for a flat that needed AFDD. Sharpen up. Dishwasher (1.5kW), w/machine (2.2 kW), tumble dryer (3 KW), are all together under 32A, so fine on a radial. Fridge/freezer can go on the ring - they consume 150 watts, even the American style fridges it is only around 250 watts. They do not continuously run as the thermostats cut them out.

The design I outlined, giving full protection to the 18th and amendments is 100% within regs. Sharpen up.

I feel like I am conversing with a confused apprentice still grappling with matters.

Will you drop the sharpen up there is absolutely no need for it in a civilised conversation and it really makes you sound like a bully

The point of this group is for discussion just because someone doesn't agree with you there is no need to belittle them when they present an alternative point of view

You are certainly living up to your profile of Manufacturer / Distributor / Supplier / Inventor - etc and in this thread you have met all four of the areas you operate in

 

[John-SJW]

And this circuit will satisfy Regulation 531.3.2 (iii).

Yep. 32A RCBO with 4mm cable radial serving three FCUs. Show me where any reg say it is illegal?

You could have it on a 2.5mm ring, but there may be a danger of the 2.5mm on one of the legs of the ring being over loaded. So 4mm is 100% safe.

I find it amazing that two guys here cannot figure out a simple design and not even know it conform to the 18th and amendments.

It you stop being a contentious know-it-all not knowing too much, with a wandering mind, I may treat you differently. You think flats have garages and EV chargers. You have not much a clue.

 

[westward10]

Yep. 32A RCBO with 4mm cable radial serving three FCUs. Show me where any reg say it is illegal?

You could have it on a 2.5mm ring, but there may be a danger of the 2.5mm on one of the legs of the ring being over loaded. So 4mm is 100% safe.

I find it amazing that two guys here cannot figure out a simple design and not even know it conform to the 18th and amendments.

It you stop being a contentious know-it-all not knowing too much, with a wandering mind, I may treat you differently. You think flats have garages and EV chargers. You have not much a clue.

Regulation 531.3.2(iii) makes no reference to cable sizing so I can only assume you have no access to the 18th Ed.

 

[John-SJW]

Will you drop the sharpen up there is absolutely no need for it in a civilised conversation

I have to get you to think and read. Your minds is all over the place.
Back to the point. The design conforms 100% to the 18th and its amendments, offering full AFDD protection to sockets. If you cannot see that why are doing the job you are in?