AFDD in 18th 2nd Amendment

[John-SJW]

It’s a big book of regulations.

If I everything was “you must do this”, “you must do that”, “ you must not do the other” then it would be even more boring than it is now reading it cover to cover

It is not a novel to read while in bed.

 

[davesparks]

“Shall” and “must” mean the same thing… you could interchange those two words in any of the regs and it would mean the same.

They aren't as interchangeable as you would think, swapping shall for must in the regulations would make them grammatically incorrect and potentially change their meaning.

 

[littlespark]

They aren't as interchangeable as you would think, swapping shall for must in the regulations would make them grammatically incorrect and potentially change their meaning.

If its grammatically incorrect, then it wouldnt be in the regs at all.

What i meant was that as long as the sentence still made sense, then shall and must can be swapped.

I wouldn't say one is as "serious" as the other... even the ten commandments used "Shall" (which could be down to translation, of course)


I think ill just sit and watch some more python videos

 

[JBW175]

If its grammatically incorrect, then it wouldnt be in the regs at all.

What i meant was that as long as the sentence still made sense, then shall and must can be swapped.

I wouldn't say one is as "serious" as the other... even the ten commandments used "Shall" (which could be down to translation, of course)


I think ill just sit and watch some more python videos

We had an eleventh commandment when I was at school. It belonged to my physics teacher Mr Shaw; he was a mean aim with a board rubber.

“Right boys, you all know the 10 commandments, we’ll here’s the 11th, Shaws’ rule; Thou shall not prat about!”

The old bugger wasn’t one for nonsense.

 

[littlespark]

Tangent!

Our science teacher was a hippy Liverpudlian…. And everybody he disagreed with was a “great steaming wassack!”

 

[mainline]

Just did a bit of digging as I know there have been changes to these boards over the years, but can not find anything which confirms if aluminium was ever used for the enclosure. I know they used to be (probably still are) cast, rather than pressed, which might account for the odd feel it had when drilling.

Try a search for the CFGAR1-BD

 

[mainline]

Try a search for the CFGAR1-BD

Not listed on the Bg site as far as I can see, but lots of other Sites, all saying aluminium.

If this is indeed the case, it should put an end to the debate of whether steel is effectively the only permissible material.

 

[nicebutdim]

Not listed on the Bg site as far as I can see, but lots of other Sites, all saying aluminium.

If this is indeed the case, it should put an end to the debate of whether steel is effectively the only permissible material.

It may not put an end to the debate as it's now an obsolete part number.

I wonder exactly when it became obsolete - prior to, or after, introduction of requirement for non- combustible material?

 

[mainline]

It may not put an end to the debate as it's now an obsolete part number.

I wonder exactly when it became obsolete - prior to, or after, introduction of requirement for non- combustible material?

Still available though and 18th compliant.

 

[nicebutdim]

Still available though and 18th compliant.

That would seem to settle the issue.

 

[John-SJW]

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.

 

[nicebutdim]

I don't see an argument in favour of such distribution. It's likely that some sparks will take that sort of approach, but I'd expect most would follow a combination of logic, regulatory guidance and sound engineering judgment to limit the possibility of overloading and nuisance tripping.

Given the potential leakage from dish washers, washing machines and fridge freezers, not to mention a plethora of other appliances likely to make their way into modern homes, I'd question the ability of anyone designing such an installation.

 

[John-SJW]

I don't see an argument in favour of such distribution. It's likely that some sparks will take that sort of approach, but I'd expect most would follow a combination of logic, regulatory guidance and sound engineering judgment to limit the possibility of overloading and nuisance tripping.

Given the potential leakage from dish washers, washing machines and fridge freezers, not to mention a plethora of other appliances likely to make their way into modern homes, I'd question the ability of anyone designing such an installation.

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.

You may not see an argument for it, and more will be on your side because of: we have always 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.

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.

 

[nicebutdim]

Nuisance tripping? Where? How?

Q1? Is it safe? Yes.
Q2? Is it legal? Yes.
Q3? Does it protect against arcing? Yes.

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.

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.

It's not a case of 'we've always done it this way' - quite the opposite, in fact, and I don't consider the questions you're applying to such design to be sufficient to ensure a problem free installation for the modern home.

There may, of course, be a significant difference between the approachs one takes for a new build or re-wire, depending on circumstances for the latter.

 

[John-SJW]

ensure a problem free installation for the modern home.

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.

 

[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.