New circuit in plastic consumer unit. Yes or no?

[timhoward]

I don't, but compared to not having one at all the chances of living are significantly higher, no?

That rather depends on the chances of live parts being exposed.
Leaving installations with TT earthing aside, they would only die if something else is already wrong or they do something rather special like stick the fork in the toaster....
If the regs are met regarding basic and fault protection, and everything exposed and conductive is correctly held at earth potential, then a fault shouldn't result in a death.
(That's why RCDs are classed as "additional protection" in the regs)

Let's also remember that the vast majority of them are not used in accordance with manufacturers instructions, and the test button is never ever pressed. I've encountered a fair few older main-switch RCD consumer units where I turn it off and it won't turn on again due to a leakage fault that's been there all along but the RCD was stuck and didn't trip. In those situations it wouldn't have saved a life as it wasn't functional!

RCD's are certainly a good idea as an extra back-stop against the unknown, and early warning of leakage faults / faulty equipment. But according to my view of the world they aren't quite as transformative as can be made out sometimes.

 

[swaRRR]

That rather depends on the chances of live parts being exposed.
Leaving installations with TT earthing aside, they would only die if something else is already wrong or they do something rather special like stick the fork in the toaster....
If the regs are met regarding basic and fault protection, and everything exposed and conductive is correctly held at earth potential, then a fault shouldn't result in a death.
(That's why RCDs are classed as "additional protection" in the regs)

Let's also remember that the vast majority of them are not used in accordance with manufacturers instructions, and the test button is never ever pressed. I've encountered a fair few older main-switch RCD consumer units where I turn it off and it won't turn on again due to a leakage fault that's been there all along but the RCD was stuck and didn't trip. In those situations it wouldn't have saved a life as it wasn't functional!

RCD's are certainly a good idea as an extra back-stop against the unknown, and early warning of leakage faults / faulty equipment. But according to my view of the world they aren't quite as transformative as can be made out sometimes.

But as a father i want to know that an RCD protection is in place should one of my dingle children decide to stick a fork in the toaster..in a domestic setting i just don't see a reason not to install one. If you can prevent idiotic events occurring in death then imo RCD protection should be a given.

Going back to the original point, I wouldn't install say a 2.5mm radial and not put RCD protection on it because it's buried 50mm deep for example. Even if someone said it was allowed i wouldn't do it.

 

[timhoward]

But as a father i want to know that an RCD protection is in place should one of my dingle children decide to stick a fork in the toaster..

Completely understood! As a father when we moved house and found the electric shower was on a 30 amp fuse I did a board change pretty quickly too, so I think we agree on this point!
I've also just advised a church that having a 3036 board in a hall that is used by children's groups isn't really on these days.

I'm not saying we shouldn't install RCDs. Maybe I misinterpreted your point, it looked as though you were suggesting not having one was dangerous in itself.
My point is that in the risk management game RCD's only come into play when the low-likelihood events happen, and then as you point out they can make a big difference (if they actually work).

 

[timhoward]

Going back to the original point, I wouldn't install say a 2.5mm radial and not put RCD protection on it because it's buried 50mm deep for example. Even if someone said it was allowed i wouldn't do it.

There's the odd exception. If we are sticking to domestic, I might possibly do this for a smoke alarm circuit in some circumstances. If it was a split load board and all required regs were met I'd happily favour the non-protected side over a shared RCD.
Every day is different and everything is weighed up!

 

[telectrix]

Dont want to say too much else I would be a hypocrite, but thats like me would never fit a light switch inside a bathroom no matter what.

whyever why not?

 

[DPG]

whyever why not?

See the thread from yesterday for one example.

 

[UNG]

But as a father i want to know that an RCD protection is in place should one of my dingle children decide to stick a fork in the toaster..in a domestic setting i just don't see a reason not to install one.

Would it not be prudent to teach your kids the dangers of sticking a fork in the toaster rather than relying on something that can fail

If you can prevent idiotic events occurring in death then imo RCD protection should be a given.

And the big problem is we left common sense behind many years ago. the reduction in testing of RCD's in the latest 18th edition amendment will IMO end up with a lot of potentially faulty RCD's remaining in service which may have an outcome of more idiots dying

 

[Lister1987]

One person's engineering judgement may differ from the next and that's fine, as long as the fundamentals are met. It could be an excessive application of 132.16 BUT equally it could be a valid application depending on the points put forward.

Another way to look at is its been considerable time since plastic boards were first allowed (16th? I don't know but I'm guessing close to 20 years?) and plastic does, over time degrade, even on a molecular level, so the drive to change to metal is a valid one (product life expiration).

Some would say its using a sledgehammer to crack a nut but if the end result is a safer installation, is that not the end goal?

 

[brianmoooore]

Another way to look at is its been considerable time since plastic boards were first allowed (16th? I don't know but I'm guessing close to 20 years?) and plastic does, over time degrade, even on a molecular level, so the drive to change to metal is a valid one (product life expiration).

Some would say its using a sledgehammer to crack a nut but if the end result is a safer installation, is that not the end goal?

Definitely not 20 years. I only ever fitted one domestic metal CU, and I've not been out of the game that long.
I'm yet to be convinced that a metal CU is inherently safer than a plastic one, with the possibility of incomers shorting to the steel, and outgoing cables passing through sharp edged holes that may or may not still have a grommet fitted, even if one was fitted on installation.
The only heat damaged plastic CUs I've ever seen have been down to poor workmanship, coupled with poor terminal design on the components in the CU.

 

[UNG]

Another way to look at is its been considerable time since plastic boards were first allowed (16th? I don't know but I'm guessing close to 20 years?)

16th edition was circa 1992

and plastic does, over time degrade, even on a molecular level, so the drive to change to metal is a valid one (product life expiration).

So when do you expect the manufacturers to introduce metal MCB's / RCBO's as using your argument they must have a similar degradation rate on the plastic

 

[brianmoooore]

I've seen many more 'degraded' steel CUs/switch fuses than I have plastic ones. Holes big enough to put your hand through in some cases.

 

[7029 dave]

I've seen many more 'degraded' steel CUs/switch fuses than I have plastic ones. Holes big enough to put your hand through in some cases.

Yup they get eaten with rust in external boxes.

 

[Dartlec]

One person's engineering judgement may differ from the next and that's fine, as long as the fundamentals are met. It could be an excessive application of 132.16 BUT equally it could be a valid application depending on the points put forward.

Another way to look at is its been considerable time since plastic boards were first allowed (16th? I don't know but I'm guessing close to 20 years?) and plastic does, over time degrade, even on a molecular level, so the drive to change to metal is a valid one (product life expiration).

Some would say its using a sledgehammer to crack a nut but if the end result is a safer installation, is that not the end goal?

Not sure plastic boards were ever 'first allowed' in that sense. Up until the 18th there was nothing in 7671 about the material a CU could be as far as I know.

It may be that there was something that updated in the standard for consumer units/enclosures (now BS EN 61439-3, was 60439, possibly was something else before then) . Some of the standards for main switches etc changed over in about 1991/2 if I recall correctly.

After all the standard 3036 Wylex boards were largely in wood and installed pretty much everywhere well into the 70s and even into 80s maybe in some places.

 

[7029 dave]

The early wylex 3036 CU 4way upwards had 60A dp switch, then changed to 100A later on.

 

[swaRRR]

Would it not be prudent to teach your kids the dangers of sticking a fork in the toaster rather than relying on something that can fail

Kids do lots of stupid things that they know they shouldn't, and sometimes forget and do things by accident that are dangerous.

I see no reason to not install without RCD in a domestic setting. Personally i won't do it.

 

[swaRRR]

One person's engineering judgement may differ from the next and that's fine, as long as the fundamentals are met. It could be an excessive application of 132.16 BUT equally it could be a valid application depending on the points put forward.

Another way to look at is its been considerable time since plastic boards were first allowed (16th? I don't know but I'm guessing close to 20 years?) and plastic does, over time degrade, even on a molecular level, so the drive to change to metal is a valid one (product life expiration).

Some would say its using a sledgehammer to crack a nut but if the end result is a safer installation, is that not the end goal?

By this logic trunking, conduit, MCB's, RCD's, meters, all light switches and sockets, clips, cleats....etc etc, should all be metal.

I'm not convinced metal is inherently safer. On the continent they use plastic and deem it fine. I suspect the change to metal-only is one of those 'we need to change stuff to justify our existence' changes that do little but mean more work gets divvied out in the name of regulation.

 

[pc1966]

Strictly speaking the regs don't demand metal only that it is of a non-combustible material, of which steel is given as an example.

Really it makes sense not to have something that is vulnerable to fire, even if the underlying reason for the fires has often been poor workmanship. More so if the CU has more stuff in it that might cause a significant heat source such as SPD under heavy surge conditions, or transformers or other electronics.

 

[pc1966]

Maybe we can bring back Bakelite ?

 

[7029 dave]

I have never been keen on the modular CU's, practically a skeleton board which you have to build up busbar etc, bound to be more of a fire risk has sweet FA to do with metal or plastic.
Single screws on everything with clamp design (far too much to go wrong), should of stuck with the double screws/solid factory inbuilt busbar.
IMO if they stuck with that concept would be less electrical fires.

 

[westward10]

Maybe we can bring back Bakelite ?

Bakelite has thermosetting properties and you could argue it is compliant to current requirements.