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Dedicated Mains / Memera / Roy K Riches

Big thank you to Arthur for sending me the RKR documents.

If l can help anybody interested, let me know by PM.

We have nearly completed installing a dedicated mains: 4 radials in 16mm2 t&e with a dedicated CU by Hager fitted with 32a RCBO's and terminated in 60a oval junction boxes. First stage is to bond to existing earth and possibly later sink a earthing rod. Flexible mains cables terminated in IEC's will be run directly from the junction boxes. We intend testing various brands of cable. I will post results here.
 
There's some horrible karma at work here: somebody resurrecting this thread after all these years!

A few years back I panic-bought a Memera consumer unit, and all the MCBs needed to go in it, because I'd read here that they were not making them any more. Last month I got a Sparks in to fit it (no, I didn't exactly rush myself!), put up with all th eye-rolling when I told him why I wanted this particular board, then proudly produced it for him, only to be told he can't fit it because it's plastic and they're only allowed to fit metal ones now. Ho hum...
 
There's some horrible karma at work here: somebody resurrecting this thread after all these years!

A few years back I panic-bought a Memera consumer unit, and all the MCBs needed to go in it, because I'd read here that they were not making them any more. Last month I got a Sparks in to fit it (no, I didn't exactly rush myself!), put up with all th eye-rolling when I told him why I wanted this particular board, then proudly produced it for him, only to be told he can't fit it because it's plastic and they're only allowed to fit metal ones now. Ho hum...

Yes, it's called a mains surge !:D I must admit, I was also gob-smacked by its resurrection.

I knew Memera had finished or changed, but I'd no idea of the change in fitting regulation. For the life of me, I can't think how metal is better than plastic (for insulation?) but maybe it's an earthing thing; still can't understand why, though.

Hope you could still use the MBs (or MCBOs, which are much dearer?). That's a sad tale (silly, too !):(
 
I have five 32A MCBOs if anyone is short of some for a Memera setup. PM if interested.
 
Big thank you to Arthur for sending me the RKR documents.

If l can help anybody interested, let me know by PM.

We have nearly completed installing a dedicated mains: 4 radials in 16mm2 t&e with a dedicated CU by Hager fitted with 32a RCBO's and terminated in 60a oval junction boxes. First stage is to bond to existing earth and possibly later sink a earthing rod. Flexible mains cables terminated in IEC's will be run directly from the junction boxes. We intend testing various brands of cable. I will post results here.

16mm2 radials !!!!! That's over-egging the pudding a bit.:) Anyway, good luck to you. Wonder if these are dedicated to each piece of kit or whether you'll have to spur off one or more.

Not sure about the junction boxes, though. I've got my radials hard-wired to 100 amp. terminal (?) blocks (plastic screw-in things)
 
FWIW I recently had my 8-way 80s fuse-wire CU (which powered most of the house) and the dedicated Memera AD6 CU (which did AV and - more recently - EV charging (OUC, not a 32A dedicated feed)) with a single 12-way. Can't honestly say there's any audible difference; in my case, I think I gained a lot by moving from the old fuse-wire box to the Memera, but between that and the new CU there's bugger all difference....
 
Big thank you to Arthur for sending me the RKR documents.

If l can help anybody interested, let me know by PM.

We have nearly completed installing a dedicated mains: 4 radials in 16mm2 t&e with a dedicated CU by Hager fitted with 32a RCBO's and terminated in 60a oval junction boxes. First stage is to bond to existing earth and possibly later sink a earthing rod. Flexible mains cables terminated in IEC's will be run directly from the junction boxes. We intend testing various brands of cable. I will post results here.

Hello Alto, I've read the RKR papers and it all seems logical, however how are you going to protect the IEC cables which I doubt are rated at 32A (most of the connectors seem to be 10A rated) - it's a serious question as I'm considering a similar approach myself.

How did you decide on the Hager box? I know in the past, someone (it might have been RKR) compared the 'sound' of 6 different CU's - but of course none of them meet current regs.

On the radial side, I've been discussing (for some long time) the possibility of using a split concentric cable rather than twin and earth. Logic suggests the 'best' cable form would be a twisted pair (live/neutral) with earth running alongside - but I've not yet found a cable that offers this, and doing it all in conduit seems a bit of a pain!

Good luck. Bill
 
....however how are you going to protect the IEC cables which I doubt are rated at 32A (most of the connectors seem to be 10A rated) - it's a serious question as I'm considering a similar approach myself.


On the radial side, I've been discussing (for some long time) the possibility of using a split concentric cable rather than twin and earth. Logic suggests the 'best' cable form would be a twisted pair (live/neutral) with earth running alongside - but I've not yet found a cable that offers this, and doing it all in conduit seems a bit of a pain!

Good luck. Bill

Protect from what? An enormous current surge from a sub-station lightning strike or similar highly unlikely, albeit not impossible, event? If it's that severe, there's the likelihood it would trip the MCB, but of course if any earth leakage results, the RCD element would close even quicker. Chances are that this, if severe enough, would even bypass some case fuses, let alone leads.

Like most things in life, 100% security cannot be guaranteed, but modern domestic mains distribution is many many times safer than, say, 30 years ago.

Russ Andrews does, or did, a dedicated mains twisted loom, at incredible cost, marketing its RFI reduction properties. I guess it must have had an accompanying earth wire. However, the current rating was quite abysmal.
 
For the life of me, I can't think how metal is better than plastic (for insulation?) but maybe it's an earthing thing; still can't understand why, though.

FWIW, having had a house built recently, I can confirm that Oz regs (or Victorian regs, at least) allow plastic CUs.

Andy
 
Protect from what? An enormous current surge from a sub-station lightning strike or similar highly unlikely, albeit not impossible, event? If it's that severe, there's the likelihood it would trip the MCB, but of course if any earth leakage results, the RCD element would close even quicker. Chances are that this, if severe enough, would even bypass some case fuses, let alone leads.

I'm simply asking whether alto is happy with using a 32A RCBO to protect a cable rated for 10A aginst faults in the downstream equipment. The whole logic of plug fuses on ring circuits is effectively for this purpose. So, I suppose however unlikely, if there were to be an equipment short between live and neutral (but not earth) then the IEC (and possibly the equipment short, depending on internal fuses) could be subjected to 32A continuous current and possibility of fire.

Three or four years ago a neighbouring farm house burnt down - anecdotally the cause was a builder's faulty drill battery charger, I don't know what the electrical set-up was, but so far I understand that the insurance company have refused to pay out - it's still propped up with scaffolding and looking very sad!

Cheers. Bill
 
FWIW, having had a house built recently, I can confirm that Oz regs (or Victorian regs, at least) allow plastic CUs.

Andy

Maybe Aussie electricians are a cut above British ones, as most if not all the reasons for getting rid of plastic C.U.s are the consequences of faulty or slack workmanship, and the evidence accumulated to bring this change looks rather flimsy, according to the details in the link.

Sheer bureaucracy, i.m.o. Still, at least,it wasn't made retrospective.
 
Whereas I've long been an advocate of dedicated mains (5 installations in 30 years), this has been based upon my, and many others' ownership of Naim, as well as other s/s stuff.

For the past couple of years I've wondered if the benefits translate to valved kit in the same way, as I've gradually moved over from s/s (over about 6/7 years).

When I posted this point on another thread here recently, wondering whether the differences between toroidal and other trannies might account for this, a number of knowledgeable replies indicated that this may well be true.

Regardless, there are only upsides to having a separate supply to one's kit and I won't be dismantling mine any time soon (too big a job anyway ! :))
 
To clarify (as I neglected to say this) I didn't have the dedicated HiFi/AV radials and rings consolidated into the regular house ring circuits when the new CU was installed, so I still have the same benefits as with the dedicated CU, albeit as part of one larger CU (12-way). It may be that there is a tiny degradation owing to having it all in one CU and/or maybe the change to a different brand of CU and the use of shared RCDs, but if there is it's not obvious to me.
 


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