New circuit in plastic consumer unit. Yes or no?

[swaRRR]

I work with someone who really isn't happy installing new circuits into plastic consumer units.

Sometimes he refuses to do it if the board in question isn't in a great state or if the existing wiring is spaghetti junction.

Obviously the regs state that it's fine to add if the board conforms to the regs at time of installation, but he argues that they're not law they're guidelines and that if he's not happy doing it then he doesn't have to and has every right to refuse.

My take is, if site told me to install a cable without RCD protection and said it was fine because the cable was >50mm in a wall, i still wouldn't do it even though allowed in regs. A similar although not identical scenario.

What do you all think?

 

[Spoon]

If your workmate is worried about adding a circuit to a plastic CU cause of the fire regs then they could always add one of these.

 

[littlespark]

If your workmate is worried about adding a circuit to a plastic CU cause of the fire regs then they could always add one of these.

Just looked. Good idea.

Nice how the fourth picture in the step by step fitting instructions doesnt show the fixing screws sticking through the lid.


Back to the thread.
So what does your mate do? Walk away from the job unless customer agrees to a whole new board? That’s some upsell….. or fit a garage board next to the plastic one just for one new circuit?
With SPD of course

 

[Pretty Mouth]

I think it's his right to refuse if he wants (we've all walked away from work we didn't like the look of), but he'll lose work to the next guy as a result.

 

[James]

Obviously the regs state that it's fine to add if the board conforms to the regs at time of installation, but he argues that they're not law they're guidelines and that if he's not happy doing it then he doesn't have to and has every right to refuse.

if they are self employed, then that’s fine they can turn down as much work as they like.
if they were working for me and were often refusing to carry out the work list because of there own invented rules instead of the applicable regulations, they would need to find a new employer fast.

My take is, if site told me to install a cable without RCD protection and said it was fine because the cable was >50mm in a wall, i still wouldn't do it even though allowed in regs. A similar although not identical scenario.

What do you all think?

Why people decide that they know better and will invent there own restrictions instead of following the regulations always amazes me.

I prefer to work with people who have a “how can we do this” attitude
so many people seem to spend a lot of time researching or inventing reasons why they can’t do what is a reasonable request.

 

[swaRRR]

if they are self employed, then that’s fine they can turn down as much work as they like.
if they were working for me and were often refusing to carry out the work list because of there own invented rules instead of the applicable regulations, they would need to find a new employer fast.

Why people decide that they know better and will invent there own restrictions instead of following the regulations always amazes me.

I prefer to work with people who have a “how can we do this” attitude
so many people seem to spend a lot of time researching or inventing reasons why they can’t do what is a reasonable request.

I see what you're saying - i personally would be completely fine with putting the MCB into a plastic box.

However i wouldn't put a circuit away without RCD protection just because it was buried 50mm in the wall. Would you consider that reasonable even though it's allowed in the regs?

 

[littlespark]

I see what you're saying - i personally would be completely fine with putting the MCB into a plastic box.

However i wouldn't put a circuit away without RCD protection just because it was buried 50mm in the wall. Would you consider that reasonable even though it's allowed in the regs?

RCD on a circuit isn't just for cables buried less than 50mm... Its All sockets, everything in a bathroom, all luminaires....
There's very little that DOESN'T require RCD nowadays.

Reading the OP again, he is right in saying that the regs are guidelines. There's no reason he cant go over and above what it says.
Fine if he is the boss, but if he works for someone else, hes just causing grief over nothing.

 

[swaRRR]

RCD on a circuit isn't just for cables buried less than 50mm... Its All sockets, everything in a bathroom, all luminaires....
There's very little that DOESN'T require RCD nowadays.

Reading the OP again, he is right in saying that the regs are guidelines. There's no reason he cant go over and above what it says.
Fine if he is the boss, but if he works for someone else, hes just causing grief over nothing.

But as i said (not sure if it's current regs or whether it was regs in the 17th) it's pretty common knowledge that you don't need RCD protection if a cable is >50mm in a wall.

I would not install a circuit with no RCD protection on it full stop.

Would that be wrong? I see it as a similar situation to this.

 

[timhoward]

But as i said (not sure if it's current regs or whether it was regs in the 17th) it's pretty common knowledge that you don't need RCD protection if a cable is >50mm in a wall.

It's not really that simple.
There are two distinct area's of regs:
1) when you need to use an rcd
2) how to meet impact protection
This was the case in 17th edition too.

From memory 17th edition required an rcd for all sockets over 20A unless a circuit was dedicated for certain purposes (e.g. freezers), circuits for mobile equipment up to 32A for use outdoors, and special locations. Someone will correct me I'm sure, it's been a while!

For impact protection it was either > 50mm, or in earthed containment/cable, or rcd protected.

18th Edition has added several things to the number 1 list, like domestic lighting, and all sockets including 3 phase up to 32 amps, but the impact protection is basically the same.
Amendment 2 of 18th has removed some loopholes (risk assessments have more clearly defined standards) which basically means almost everything (domestic) needs one now.

 

[James]

It is rare that I install an rcd on anything,
sockets, yes most have an rcd.
but to suggest that you should rcd everything you install is taking things too far .

 

[westward10]

Outside domestic which is where I work I avoid rcds at all costs.

 

[7029 dave]

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.

 

[pc1966]

Amendment 2 of 18th has removed some loopholes (risk assessments have more clearly defined standards) which basically means almost everything (domestic) needs one now.

Essentially yes, as when you go to do a CU change typically you will have no idea if the cables are < 50mm from surfaces, etc, and lights & sockets & bathroom now need RCD anyway, so it is simpler to just RCD (or preferably) RCBO the lot.

The likes of Fusebox RCBOs and similar are not that expensive, not really compared to a day or so of skilled labour.

But for non-domestic you will often find few RCDs except for the essentials that are mandated (socket outlets, etc) or otherwise a high risk.

TT of course adds a while other dimension...

 

[pc1966]

But back to the OP's question about adding to a plastic CU. To me there is no fundamental reason why that is not acceptable, but if the CU is, or will end up, as a C2 for EICR then it would be a no. For example, you can't get a compatible RCBO/RCD, or the enclosure is damaged or thermal stress, etc.

As above, sometimes you see something so hideous that you can't face working on it and then you might well decline or better still take a photo and explain to the owner in reasonably understandable language just what is wrong with it.

My own recent sins (couple of years back) include adding another circuit to a rewirable board. It was one of the metal ones and an ex-council house where the wiring was in pretty good condition overall. But the monkeys who had fitted the solar panels had put the feed in parallel with some other circuit's fuse. So putting it on a new plug-in MCB (as it did not need additional RCD protection) seemed like the least-worst thing to do. My tests were "Is there anything fundamentally dangerous about it?" and "Is this going to be safer than the current arrangement?"

 

[swaRRR]

It is rare that I install an rcd on anything,
sockets, yes most have an rcd.
but to suggest that you should rcd everything you install is taking things too far .

But in a domestic setting what stops humans from dying if circuits aren't on RCD's? (Sorry i should have mentioned that i'm talking about domestic since that's where we work.)

 

[swaRRR]

Outside domestic which is where I work I avoid rcds at all costs.

Why? Is there a disadvantage to having them in industrial/commercial settings? Something to do with leakage i presume?

 

[westward10]

Why? Is there a disadvantage to having them in industrial/commercial settings? Something to do with leakage i presume?

To avoid nuisance tripping they are a pain, a 'normal' protective device provides adequate circuit protection providing all criteria is met.

 

[westward10]

But in a domestic setting what stops humans from dying if circuits aren't on RCD's? (Sorry i should have mentioned that i'm talking about domestic since that's where we work.)

Never assume a rcd will save your life.

 

[pc1966]

Why? Is there a disadvantage to having them in industrial/commercial settings? Something to do with leakage i presume?

As @westward10 has said, you might have random trips due to leakage or noise (e.g. welder, large motors switching) and if the DB is locked (normal outside of domestic) then you get even more grief.

For most industrial equipment with proper earth bonding the traditional ADS disconnection requirements are sufficient to protect personnel from electric shock danger. Also most commercial/industrial sites have better PAT testing regimes than domestic, and you rarely have wet or outside areas where the risk of shock is highest.

Where RCD really do offer an advantage is outdoors or other areas where DIY modifications can result in cable damage. But I would never test one with my life! The trip curve should protect you, but it is not guaranteed, it is very painful, and occasionally an RCD fails. I don't know if the RCD failure rate is higher or lower than parachutes for recreational jumping, but I would guess parachutes are tested more often!

 

[swaRRR]

Never assume a rcd will save your life.

I don't, but compared to not having one at all the chances of living are significantly higher, 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.