Boiler, programmer etc. via immersion heater circuit?

[RobMark]

Can I supply my central heating (programmer, two port valves and boiler) via a fused spur taken from the immersion heater circuit?

They’re currently supplied from a fused spur taken off the ring main; however, kitchen wall’s are being moved around.

There is nothing else on the immersion circuit (only the cylinder if boiler fails). The circuit is protected by a RTA061630B RCBO (see pic).

 

[Simon47]

Short answer - yes.
However, you might want to consider what happens if the circuit develops a fault - you'll lose both your boiler and the immersion, meaning the immersion won't be able to give you hot water. That's a fairly unlikely situations unless the cable gets damaged or the RCBO fails - if either the immersion or the boiler&controls develops a fault, as long as both have double pole switching, then the fault can be isolated.
Personally, I'd use a single socket and plug for the boiler. Pulling the plug out is acceptable as a means of isolation, and it means that you can use an extension lead to plug it in somewhere else if needed. However, some heating people still think it's not allowed and you must use an FCU - they are wrong. The guy seemed a bit annoyed when I made him retrieve the socket form the rubbish box and put it back when mother had a new boiler installed.

 

[littlespark]

Can I be first to mention mismatched devices in the consumer unit??

 

[RobMark]

Can I be first to mention mismatched devices in the consumer unit??

Please do. This CU is from a 2001 build, and according to previous home owner has never been touched. An EICR was carried out less than 6 months ago with no issues. However, I've found a few things that dont follow regs. Anything odd, I'd like to put right.

 

[littlespark]

F&G, I’ve never heard of… fusebox are relatively new, so those rcbo’s have been added in the last few years to give those three circuits rcd protection.
Would have just been mcbs when new, when the regs only required RCDs on sockets.

 

[Risteard]

F&G, I’ve never heard of… fusebox are relatively new, so those rcbo’s have been added in the last few years to give those three circuits rcd protection.
Would have just been mcbs when new, when the regs only required RCDs on sockets.

I've seen them before, but only come across 2 mod RCBOs for them. Doesn't excuse the incompatible products obviously.

 

[littlespark]

I've seen them before, but only come across 2 mod RCBOs for them. Doesn't excuse the incompatible products obviously.

Maybe “compatible” just because it fits…. But “untested” according to manufacturers designs.

Very few circuit breakers and similar devices are truly compatible.
Only when one company is taken over by another, and the new company uses the old designs with a new badge…

MEM and Lewden are the only ones that spring to mind.

Even upgraded devices from the same manufacturer may not fit an older type board…. Even though they appear very similar.

 

[RobMark]

The CU is an F&G Concept 2000 (moeller?) fitted in 2001. I now 'suspect' the addition of the RCBOs may now have been carried out during the EICR mid 2022. The wife reminded me that the previous owner showed us some old MCBs that had been replaced recently. So old defunct CU, with additional newish RCBOs. I assume the only workaround is a new CU to be on the safe side?

 

[Simon47]

In practical terms, the main issue is that the cable/busbar entries aren't standardised - while the form factor (overall shape in terms fo DIN rail fitting and opening in the front panel) is. As long as the different devices aren't pulling the busbar in different directions (typically further away or closer to the DIN rail) then there's likely to be no problems at all.
In theory, there could be electromagnetic interference between one of the RCBOs and the adjacent RCD, but personally I think that's unlikely.
What you can see, and which would be more of a concern to me, is that if you look at the main isolator, I suspect the terminals were tightened by a gorilla on steroids. The case of the switch is distorted (the printing doesn't line up across the two case halves of each pole), and it's tilted slightly to the right - so by the time you get the case front on, you end up with the gap above the other devices visible in the photo.

But, if having an EICR done, then the inspector (if they actually inspect rather than make up some test results and fill in the paperwork in the car outside) will flag this up. In a domestic situation, the regs require the use of a type tested distribution board - and since manufacturers aren't in the habit of approving mixes of their own stuff with random competitors, that means using only the devices the manufacturer specifies for that board. My guess would be that the EICR flagged up circuits "not to current standards" due to lack of RCD protection, and the previous owner had these RCBOs fitted to fix that. The EICR should show either non-RCD circuits, or the non-compliant devices.
Some will disagree, but I'd give this a C3 (improvement recommended) which leaves it up to you whether you wish to change it.
Changing the board is an option if you wish to, the fact that it's a plastic case may be cause for another C3 - but that's open to even more debate (many wouldn't even flag it, especially if it's not somewhere where the case burning would impede exit in the case of an electrical fire in the CU's innards*.

* <rant mode> Current regs (because they were very very badly written) require a ferrous (steel) case. Consensus isn't that there's a problem with plastic cases (and conductive steel ones introduce their own risks), but that the London Fire Brigade (LFB) observed an increase in fires starting at the CU and therefore demanded that "something be done". The fact that the rise in fires coincides with the rise of (so called) "smart" meter installs by people dragged off the street and pushed through the shortest training possible didn't seem to have occurred to either the LFB or the committee that added the requirement for steel boxes.
The regs don't actually specify that a steel case is required, they specify that the case be non-combustible without specifying what that means (e.g. by refferring to existing standards on material combustibility) - and thus making it effectively impossible to comply. But they added a note that ferrous metals are deemed to be non-combustible, and thus created a situation where the only route to compliance is with a metal box, even though there are plenty of other materials that could comply if the regulation specified what the criteria were.<end of rant>

 

[littlespark]

You can judge C3’s as long as your arm, like you say there’s no demand they must be repaired like a C1 or 2.

So if not non-combustible… C3 every day.

 

[Simon47]

So if not non-combustible… C3 every day.

I had an email conversation with a representative of the JPEL-64 committee over this some time ago. This was in the context that the (then) new regulation had suddenly made a very large number of (in some cases) very newly installed CUs somehow "dangerous". Bear in mind that a lot of organisations won't allow any C3s to be left - they insist on having a "clean" EICR as that's the only way to avoid "but there was a known and documented risk and you did nothing about it, and no it's caused me loss/injury/whatever" type claims. Even before the introduction of mandatory EICRs, I would get periodic ones for my rental properties - and I would not leave any C3 un-fixed for just that reason (yes, there are some people who would look for any opportunity to exploit it).
Anyway, the response I got was that it was expected that it would be C3 if (for example) the CU was under wooden stairs or in a fire escape route, and not mentioned otherwise. But I couldn't get that as anything more than "a personal opinion" even though it was clear that it was in fact guidance from the committee.

Don't forget that most of the plastic cases previously used will have been various self extinguishing and/or fire retardant plastics. So in the absence of a sustained source of heat, they would not continue burning. As it is, if you have the same sustained source of heat, a steel case can a) allow flames to escape (the standard for CUs doesn't mandate it present a fire barrier) and/or b) set fire to the the wood it's screwed to when it gets hot enough. Of course, if we hadn't mandated such a mass meter change program (which now doesn't actually carry a positive cost-benefit after various supposed benefits failed to be possible), and been forced to use so many "poorly trained" fitters, then we'd not have the problem anyway.

Regardless, it's a stain on the reputation of the JPEL-64 committee until they fix this - which could easily be done by changing the regulation to "non-combustible as per <some existing standard>" as that would allow other materials since it would be possible to test to a known specification. As it is, without the "ferrous metals are deemed" note, then steel would not be allowed since that is combustible if you apply enough heat and oxygen (note, the reg doesn't specify what conditions it has to be non-combustible in) - which makes a complete mockery of the reg.

 

[RobMark]

I took a look at the report. The summary is satisfactory with no C3. Item 4.18 is N/A, item 4.19 Pass.

 

[DefyG]

Can I supply my central heating (programmer, two port valves and boiler) via a fused spur taken from the immersion heater circuit?

As long as you dont intend fitting something like a solar iBoost in the foreseeable future.

 

[brianmoooore]

Re introducing a fourth test result category would help, by allowing an easy distinction between 'needs improvement' and 'doesn't comply with current regs, but did at time of installation'.

 

[Risteard]

Re introducing a fourth test result category would help, by allowing an easy distinction between 'needs improvement' and 'doesn't comply with current regs, but did at time of installation'.

Why would it be relevant whether it complied at the time of installation?