Radial vs ring wiring

Hey guys. I have been experiencing tripping of my fuse breaker whenever I switch my 500 system on. I do generally leave my gear switched on but I would still like to rectify this.

So from reading up on this forum and the archived one I was of the understanding that I need to change my breaker from a 16A B to a 32A C breaker.

So my listening room is on the first floor of my property which the electrician tells me is radial wiring. He tells me that to install the 32A breaker I would need to change it to a ring setup. Is this correct? please advise

For a radial the circuit would have to be wired in 4mm or greater, if i recall correctly.
Worth a google.

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My advice would be to go back to the electrician and explain the problem rather than skip ahead and ask about the solution. Let them propose a solution first.

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The electrician found no problem with the radial wiring that he could detect. He wasn’t able to provide a reason for the tripping of the breaker. Neither were about 5 electricians before him which is why I followed the advice on the forum.

The wiring is actually a 2.5mm radial rather than 4mm and unfortunately cannot be upgraded without taking apart a lot of things along the way. Porcelain tiling, hardwood flooring. So I think it’ll have to stay put for now.

He did say he can install a 20A break type C. Hopefully that will fix the issue but I would’ve loved it if I could have upgraded the wiring. :pensive: just to unleash the full potential of my setup.

He suggested doubling the 2.5mm wiring to accommodate the 32A breaker. Otherwise it has to be a 4mm wire

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It is nothing to do with ring of radial: the breaker there is to protect the cable. A 32A breaker is too high to protect 2.5mm2 cable. If what you have is a radial 2.5mm2 circuit then if you really need a 32A rating then you will need to either add a second 2.5mm2 cable to double up - whether or not connected as a ring if you have more than one socket - or install a radial 4mm2 (minimum) circuit, whether that replaced the existing 2.5 of is simply a new circuit. (These wire sizes assuming no excessive temperatures or insulation where the cable runs.) General opinion here is that thd dedicated heavier rating cable is the way to go.

But the first question is whether 32A is needed, or just s C curve 16A breaker - inexpensive almost instant installation by electrician to try if you haven’t - and that will depend on the total load, including peak currents such as when switched on.


Yes you’re correct. Sorry my explanation was flawed

I’ll correct my reply to ensure a future reader doesn’t folllow my poor explanation

I expect so. I’ve had all manner of Naim stacks on 15 and 20A circuits with zero issues even on 1.6mm wiring. I’m surprised none of the electricians can diagnose this and suggest a different breaker cartridge.

We have 10mm2 cable and 50 amp type C breaker. No Naim equipment has ever caused it to trip! Is there no way you can get the radial swapped for 10mm2?

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Wow I bet it sounds amazing. No unfortunately not. Had I known what I know now I would’ve made sure to install a thicker gauge cable. Oh well I guess we all compromise on some aspect of our hifi.

2.5mm cable should be protected by a breaker no larger than 20amps (if a radial circuit)
If the 16A type B keeps popping, it might be worth just trying a 16A type C, type C being correct for an inductive load. Naim transformers are an inductive load that have a high switch on inrush current.

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Spot on Mike. The electrician installed a 20A type C and all is right with the power up of the 500 series amps now. Mind you the 3 hour charge was a little difficult to swallow. London is very expensive for labour work.


What you have had done should solve your original issue. However with a 500 system, it may well worth getting a quote for a separate dedicated mains to be put in with its own Consumer Unit using 10mm cable. You might find that the electrician can give you this without another visit, as he has done some wok on the property already.

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You’re not wrong there buddy but like I said he won’t be able to install that without removing hardwood flooring that has been bolted to Marine plywood and porcelain tiling that I cannot afford to strip from a wetroom.

I wish I had known this before our last refurbiahment which was ten years ago now.

So I just got home from work and sat down for a listen. The system had been switched on right after the electrician left so pretty warmed up.

Right away I’m noticing a lower noise floor and an even more dynamic and involving sound. This is just by changing an old 16a b breaker with a 20a type C. I can only imagine what a dedicated radial 10mm2 with 32 C breaker would do.


That was similar to my issue with a dedicated circuit, but then someone pointed out the idea of going outside the build. I ignored this also for a year, then I realised that there was a fairly simple route going up the outside wall, through the loft, then down the other side of the house.

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You’re a lucky guy as I cannot even adopt that method. My listening room resides in the middle of the house.

One access is by ripping out hardwood flooring and the other is by ripping out tiling from a wet room which won’t be able to be replaced as those tiles are now old stock and therefore unavailable. I’m so impressed right now with this upgrade that I’m going to sit here plotting a way to get this done.

This is more of an upgrade than any cable I’ve ever heard. Even more than some components I’ve purchased in the past. Crazy. I guess the uplift in sound is because the gear itself is of the highest quality.


I’m contemplating something similar. My CU in located on the far wall of the attached garage and my dedicated listening room is on the other side of the house!

What’s galling is that it’s I bought it as a new build and if I’d been more clued up I could have sorted this before the internals were fitted out :weary:

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Sounds like an identical setup. I ran 10mm SWA around the house (about 35meters) into a double unswitched socket costing under £700. Cheaper than a black box upgrade.


Have you discussed the possibility of running a new cable with your electrician, or are you just assuming it would be disruptive? Professional electricians are used to fishing cables through tight spaces and minimising disruption, so they may well have ideas you hadn’t considered about how to route a new cable.


Wow I’d love to live there. Just the breaker change cost me £350 in London, which I thought was ridiculous. I think some of the labour charge is for the investigation into how to install the 10mm radial but I don’t think that took longer than an hour.

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