I wouldn’t worry too much about the RCBO rating for safety. 10mm SWA will cope with 70+ amps no matter how you install it. The current protective device is there to protect the cable, so even a 50a RCBO will be ok with that cable. For 18th Edition you will need either an RCD + MCB or just use a RCBO, they will need to be correctly specified for use in the sub board, ie same brand and type. The RCD will need to be 100a rated, the MCB suitable to protect the cable. With a RCBO you only need worry about the cable. One note, a 40a RCBO will use a larger neutral conductor than 16a ones, so this might have an effect on SQ, who knows but if you are going to the trouble of using a large cable then a large RCBO makes sense too. Also, an industrial RCBO rated at 10KA will have larger contacts than consumer grade 6KA ones, most type C RCBOs will be 10KVA rated but you can easily get type B’s rated 10KA too. Earth the SWA sheath at the distribution board as this provides cable protection from physical damage. You don’t need to connect the sheath at the socket end, just use the earth wire in the SWA itself.
Thanks for that.
Very helpful - It’s what I guessed, but glad to have confirmation.
I didn’t realise you can still have an RCD+MCB. That’s really useful to know about the 10KVA RCBO’s, as I’m sure the larger contact makes more sense. E.g. “Hager 32A Single Pole 1 Module C Curve 10kA 30mA Type A RCBO £50”. 32A seems a good upper limit as it also protects the end socket, which is unlikely to be rated higher than that. Many Thanks
Looks like very nice work, but Query, what about the upstream, incoming power from your Electricity Utility-- is it “polluted” in any way? Wouldnt a properly designed, Naim sanctioned and blessed power conditioner, be the optimum solution ?
They disapprove of them all, but good idea. I suppose as every house can have such different issues, it would be hard to have a single solution.
thought would add my recent dedicated mains install experience
i went with 6mm SY double shielded mains cable into a furutech NCF single socket (6mm was biggest socket could take safely), fed from 32A type C MCB Consumer unit that fed directly from incoming mains/same for earth) i then fed this into an airlink balanced transformer (unfiltered)
improvement was immediate and obvious, essentially giving a lower noise floor, more micro detail and less digital harshness
have recently picked up a niagara 3000 which am experimenting with (early days so far) which has further lowered noise floor, opened up sound stage more and removed digital harshness on some of my most demanding recordings, still however need to get plug order sorted and get the my supercap onto the high current unfiltered socket to see the difference it makes to sound and which i prefer (will report on this later on seperate thread probably once done some proper A/B testing)
I’m guessing you needed this for humming issues. Did you find the dedicated circuit alone helped with this, or was the BT definitely needed?
Now that’s an interesting cable - not one I’ve come across. They do seem to do it in 10mm also, and I suppose as a flex, it is easier to manage than SWA. Can I ask how this was recommended?
- Application: Used as interconnecting cable for measuring, controlling or regulation in control equipment for assembly and production lines, conveyors and for computer units. Suitable for fixed installations or for flexible use in conditions of light mechanical stress. Can be used outdoors when protected, and in dry or moist conditions indoors.The braided screen offers the best possible protection against mechanical damage and offers a level of Electro-magnetic shielding. The galvanised coating helps protect against corrosion.
Someone else’s experience will not necessarily be the same as yours as it will depend on the cause of the hum you are experiencing.
If the hum is caused by issues on your mains supply, originating outside your property, a dedicated mains circuit in your home will make no difference.
If the hum originates in your home, you might help to isolate it with a dedicated supply, although it you can identify the cause it might be preferable to repair or replace the item that is causing it.
i found the balanced transformer gave a SQ boost (had it before and after dedicated mains) and it removed noise coming through speakers i.e. hum
am an engineer so am familiar with the SY cable and the effects RF noise/phones/etc transmission can have on kit, seen/experienced this at work. was either SY cable or armoured core as cable as cable route was outside my house, so i went with the shielded option which has worked really well for me
AQ niagara 3000 been recommended by number of DAVE users and def works well with it still trying combos out though and too early to report back on this yet yet
bit more context dont know it helps or not?
Many thanks. I understood that usually Hum through the speakers is a grounding issue (other than the very faint hiss you get from Naim Amps), but if it worked for you, great. Cheers
few other users i have seen on the forum have a bigger version of the airlink transformer close to their dedicated CU using a 32A type D and have reported good success with that approach too
many ways to do it but i think best to go in stages, then test and evaluate (few also bought kit to measure their supply quality aswell, as ever can you can easily disappear down the rabbit hole in this hobby )
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