UKH

Are there any electricians on here able to offer advice about an issue I'm having getting smoke alarms wired in.

An electrician from the letting agent as made some comments about having mixed brands of MCBs in the consumer unit being a problem, is this really an issue? All work in the box has been done by qualified people and has since been given a green light by another electrician who did the EICR.

It seems odd that at least 3 different electricians have been ok with this set up and now a fourth isn't happy.

Any advice welcome thanks.

very much doubt this is anything other than a scam to charge you for new MCBs. Why not just call the one who did the EICR and get them to do it?

All the MCBs will be for different circuits so how would they even be connected (pardon the pun) 
About as relevant as the fuses in your car being of a different brand therefore failing the MOT

Sounds like a scam but as they were only ‘comments’ he was perhaps testing the water to see how gullible you were and what he could get away with perhaps

This was my thoughts but thought I'd check.

I have tried to get contact of loads of electricians but they are really hard to get hold of and I thought I'd try and get some value from the money the letting agents are charging me every month for seemingly no service.

Scam. Assuming they are all compliant with the relevant standard, IEC 60898-1.

The whole point of a standard is that they are interchangeable.

I'm not an electrician, but I've heard of this and there is something behind it. 

All MCBs are not equal. The issue is how they behave under extreme fault conditions. Put simply, you can fit a cheap MCB that might explode as long as the CU can contain the explosion. Or, you can put an MCB that won't explode in cheap CU. Because of this, MCBs should be certified to match the CU. A lot of the time another manufacturer's MCB will work fine in the CU and be safe, but it won't be certified because they didn't bother certifying it to go into a rival manufacturer's CU.

If you've got a real stickler of an electrician they might flag this as an issue.

Seriously?? They could have just written into the standard that MCBs shouldn’t explode AND CUs should contain explosions. That would have been the sensible thing to do..

Either way, I have never had a CU with only the original MCBs and despite lots of electrical work on several properties no one has flagged it. On further reading.. At most it’s best practice not a requirement, so at most a comment. They shouldn’t refuse to work in it. 
 

edit: if you follow manufacturers (ass covering rip off) guidance you’d rewire the whole property with matched equipment every time a switch was replaced (I exaggerate but not much). The regs are actually a lot less demanding.

I'm not sure it's definitely about exploding MCBs, but it is something along those lines. It's all about certification and arse-covering, nothing to do with actual safety.

There is so much BS with electrical work nowadays. They have tried to imagine every one in ten million extreme event and regulate precautions to prevent it. 

I had a sparky come and add a few more MCBs to a board for me, as I'd added a few more circuits for an extension. He's a friend and was fine with the work I'd done, and it's France anyway so any regs will be very different. But after finishing, we tested the sockets and he told me that I'd wired them with live and neutral the wrong way around, which isn't a hazard with A/C current but obviously isn't ideal for future maintenance. I was very surprised, as I'd been pretty careful to do things properly. Turned out the new MCBs he added were reversed polarity compared to the ones already in the board. So I can understand why some sparkies may not be entirely happy with a mix n match approach, even if it's unlikely to cause a fault risk.

I'm a sparks. 

https://www.electricalsafetyfirst.org.uk/professional-resources/best-practi...

Have a look at guide #4 about condition reporting, issue 7 (current one)

Page 20, half way down. Mixed branded switch gear.

Theres further reading (referenced via BEAMA in the guide) if the initial text doesnt fulfil your enquiry.

You cant tell over the internet to offer a binary answer.

A C3 is non compliant, but does not necessarily offer an unsatisfactory result. Obviously same brand is the better (? maybe?) option. Just remember that often one manufacturer makes MCBs etc for more than one brand, they just print a different label on the product.... But if youre worried about fires etc then AFDDs may offer the current gold standard. Watch your sparks face when you mention them, itll tell you a lot about your sparks. Just a word of caution, theyre relatively expensive @ 120-200+per circuit to purchase. 

Thanks for that link.  It really surprised me.  I suppose this is because the correct operation of an RCD and a downstream bank of MCBs is tested and signed off by a given manufacturer, but nobody signs off on an RCD from X feeding MCBs from Y etc?

Seems to me if there is a specification and parts are specification compliant, this should be a non issue.  That’s it’s being flagged as an issue suggests that the specifications aren’t suitably robust…? 

I think back to my childhood home of the 1980s with thermal fuses, no residual current or earth leakage protection, two core lead sheathed cables here and there…. Daft thing is we had our current property rewired to modern standards about 6 years ago, and with LED lighting the lighting circuits each run at less than 1/12th of their rated load, and about the only thing to go in to most wall sockets is a power brick.  At some point you look at the cost of a modern spec DB and all those thick cables and wonder if running 240 V AC everywhere is still the right thing to do…

That's exactly what I want to see, someone who knows what they are talking about and can point me towards the documents.

Thanks you very much.

Looking at the spec. sheets of the installed MCBs the only difference I can see is 0.5 mm difference in the width of the units, some being 17.5 mm and others 18 mm.

There are some things I'd rather not go back to and am happy to stick to regs for.

My sisters house had a wooden fuse box full of bare fuse wire hand wound between posts in old ceramic insulators, it was a good day (sometime in the 2000s) when that was finally replaced.

When I took down the horrible fake wood panelling in my kitchen I found that the one double plug socket at the end of the kitchen with the kettle, fridge, toaster and washing machine plugged into was connected to a length of 16A flex that ran diagonally across the wall.

No, I wouldn’t go back, we had a year of the earth leakage trip blowing after it was fitted as fault after fault - wiring and appliance alike - gradually made themselves known.

But looking at the changes, and now looking at how few appliances need more power than a maxed out USB-C connection can give, where we are with highly expensive protection systems for highly lethal circuits capable of conveying multiple kW seems increasingly daft.  We could have a human-safe voltage (AC or DC) and low power distribution to almost everything in a house.  Hoovers were the exception that had to plug in anywhere but battery ones are there now, and much easier to use.

I can’t see it changing any time soon - but it’s interesting to think what a clean sheet approach to modern domestic power distribution might look like.

Can't help you on the electrics side at all but wired smoke alarms should now be replaced on the same timescale as wirelessly connected ones (pretty much all 10 years) and the wireless units can be connected and installed by anyone who can stand on a chair waving a screwdriver above their head, so saves you needing to trouble an electrician.

Pleasure. Good luck. 

Winter tree. Yep. It is over spec'd, kind of... There's always many dimensions to electrics. Led lights have a high start up, in the event of a fault, the resistance of a circuit has to be below a threshold otherwise theres the chance to fault protection won't operate. Which promotes larger conductors. And best not discuss durability & temperatures of small conductors Vs large. Gotta love well insulated homes too. 

Hours of idle discussion and reg swapping one up manship to be had. 

Rent smart wales regs specify I need hard wired smoke alarms so I have no choice but to comply. I only wish I or a previous electrician who worked on the property had the crystal ball to read the Welsh Government's mind when the property was being refurbished and I could have had the work done with much less hassle.

The origin of the requirement is a bit convoluted but can be summarised as:

BS 7671 - the wiring reg's clause 421.1.201 requires domestic consumer units to comply with BS EN 61439-3. This in turn defines a series of type tests that must be carried out on the assembly. The type tests are pretty onerous and are typically only carried out by manufacturers on their own products. 

BS EN 60898-1 is applicable to the mcbs but not to the whole assembly consisting of the breakers and consumer unit. Breakers are permitted to arc and explode under credible circumstances. The assembly as a whole must comply with BS EN 61349-3 to contain this.

BS EN 61349-3 does not prohibit use of breakers from mixed manufacturers, however, the bespoke assembly would then have to be type tested which is not economical.

A satisfactory EICR in accordance with BS 7676:2018 is required by law if you are letting the property. Lack of valid type testing would probably be classed as a C3 by most EICR inspectors which allows for a satisfactory report. However, this is dependent on their professional judgement, the guidance of their particular professional registration scheme and the state of the installation itself.

If the smoke alarms require a new circuit then the new works, i.e. the new circuit, needs to comply with the current regs and use a type tested breaker from the same manufacturer as the consumer unit. The existence of adjacent non-compliant circuits does not necessarily prevent the compliant installation of the new one. If you can't source appropriate breakers then the consumer unit is probably old enough to warrant replacement.

Tldr: Single manufacturer breakers are required by the relevant standards. This is for good reasons. An existing installation can probably achieve a satisfactory EICR with breakers from different manufacturers. New circuits need the breaker to be from the same manufacturer as the consumer unit.