Does a separate mains spur for hifi make a difference?
- Thread starter junk01
- Start date
robbyd
pfm Member
this would be my answer - system is fed by its own fuse box, with not radials but 4 & 6mm rings coming from. For power amps a ring will give potentially twice the current delivery. I started with a radial feed for the power amp (other end of room), but when looping up to a ring the bass was markedly weightier. But then the max consumption is 2kw each mono...
Mike Reed
pfm Member
Not so new; you'll probably have a TT earth then., esp. if it's rural or semi-rural.
Mike Reed
pfm Member
Not sure you can get fuse boxes any longer; not that anyone would want to. Trouble with a 'dedicated' ring is that all the kit is powered from the same cable (s) which are piggybacked to sockets (presumably). A 10mm radial would do your amps and a 6mm the rest, if you're limited to two. really can't see the advantage of a ring over a radial.
Mike Reed
pfm Member
By 'technical' I thought you meant something different. Obviously, an iron bedstead or water tank would be ideal, but most people simply opt for a copper rod spike or three. Again, not a good idea in conjunction with a PME bonded earth. S'pose you could isolate the earth in the t & e cable, but somehow doubt that would pass reg's nowadays.
Mike Reed
pfm Member
I believe that the bigger cable has a correspondingly lower impedance too; utterly irrelevant according to Jez but one of the prime motivations for a dedicated radial circuit system. Theory v practice, maybe? Who knows, who cares, it's the ears that decide, i.m.o.
I would not be installing separate earth spikes, the TT earthing found in older properties relies on soil conductivity which varies on location (soil type) installation, and ... how dry the soil is. Power distribution companies don't do it this way anymore, it is just too variable, why would you add a variable poorer earth to your system? If you are very careful and install a massive earth have the right soil and are somewhere that never dries out (global warming anyone?) you might improve on your existing earth if you have a TT installation ... otherwise I suspect this is only going to be worse.
The thing with radial circuits is you have to have larger cables for the same current, the ring shares the load, so a 2.5mm ring may be protected by a 32 amp breaker safe in the knowledge the breaker goes before the cable melts. For a radial circuit you need 6mm for that same 32 amp breaker, or the cable melts before the breaker goes. (There are limits on the length of ring/radial and breaker types that make these typical circuits but you get the idea.) Your hifi will only ever draw anything approaching these limits if it had a serious fault.
The thing with radial circuits is you have to have larger cables for the same current, the ring shares the load, so a 2.5mm ring may be protected by a 32 amp breaker safe in the knowledge the breaker goes before the cable melts. For a radial circuit you need 6mm for that same 32 amp breaker, or the cable melts before the breaker goes. (There are limits on the length of ring/radial and breaker types that make these typical circuits but you get the idea.) Your hifi will only ever draw anything approaching these limits if it had a serious fault.
Mike Reed
pfm Member
That's a useful comparison; thanks. Mind you, anyone thinking about a radial circuit installation shouldn't really look at anything below 6mm2 anyway.
ToTo Man
the band not the dog
Knowing absolutely nothing about electricity distribution, can someone please explain to me how a separate supply for the hifi is theoretically beneficial from the view of preventing 'noisy appliances' (fridges etc) from injecting noise back onto the supply? The separate supplies are inevitably going to meet at the main house box, aren't they? So what prevents noise that's present on one supply from contaminating the other? And if you extrapolate further, what prevents noise from your various neighbours' supplies from polluting your own supply? Surely rings and radials will both be affected by this?
Blackmetalboon
pfm Member
None that are worth the cost, temporary disruption, possible redecoration involved in installing a separate consumer unit and dedicated circuit.
Yes, they will be connected together at some point after the electricity meter.
Nothing.
Nothing & yes.
Whatsisnaim
pfm Member
You will get some isolation from stuff in your own house, which is a reason for splitting the dedicated supply (and earth) as far back in the system as possible, i.e. immediately after the meter, rather than from the main consumer unit. But if you have contamination from other mains appliances, prevention is better than cure, and elimination of electrically noisy appliances is a better approach. As for noise entering from outside your own home, of course the dedicated circuit will make no difference.
Mike Reed
pfm Member
Somewhat cynically covered by Blkmetalboon above, but let's look at this in more detail. There's nothing which can be done on the supply side of the main fuse (or meter, if you wish); you get what you're supplied with on that phase. However, the internal supply is split into two directions; the domestic c.u. and the hifi c.u.
The hifi c.u. enables individual control/security, depending on how many radials you want. It is not influenced by appliances, switches or other devices used on your domestic ring, except in the rare case of airborne surges from bad switches. The impedance of your hifi supplies should be well down on the domestic ring. As regards hifi dedicated ring or radial, as I've mentioned above, my choice would be the radial, which is used throughout the world except in the U.K. The ring main was an economy measure (copper price?) introduced after the war. Strange that nobody else copied it !
Blackmetalboon
pfm Member
Well said. A little time spent hunting down problematic appliances could be well worth the effort. Replacing an old light switch or appliance could also be far more cost effective, leaving more money for music!
You know me well!
The UK uses radial circuits all the time. The intended usage will generally determine what type of circuit is used. For a couple of dedicated sockets just for a Hifi, a ring main is probably overkill and a radial circuit better suited.
The ring main (technically it’s actually called a Ring Final Circuit) was introduced post war as it was calculated to use less copper than radial circuits that were traditionally used.
Mike Reed
pfm Member
You know me well!
I echo that remark as above.
Mike Reed
pfm Member
For domestic use? I didn't know that. I thought ring mains had been de rigeur here since their introduction.
Yes, they are used for things like outbuildings and garages to save cost. My house, built 1989, has a modern CU and a few ring mains. The garage is on its own radial, with only 1 run of cable and a 5A breaker. It reflects the fact that most people only want to plug in a mower or hoover so why waste the money on wiring?
Blackmetalboon
pfm Member
They are the norm, although for how much longer is up for debate. Arc Fault Detection Devices (AFDD) have been introduced into the 18th Edition Regs (they are only recommended at the moment but will likely be a requirement in future amendments/regs) but they are unable to detect a specific arc fault on a ring.
Heavy loads will usually have their own dedicated radial circuit (showers, cookers, immersion heaters) the only difference is that it usually isn’t terminated into a socket. Or in certain situations it is just quicker, easier and cheaper to install a socket on a radial circuit.
Mike Reed
pfm Member
Sorry. I was of course aware of radials being used for electrically heated showers, cooker points, outbuildings and most electric hobs (cooker points), and have one or two in my own properties. I was expressing surprise that general house radial systems were now common. Bit of confusion there, methinks.
Pterodactyl
pfm Member
Tiggers (and others who have done a dedicated line and not heard a difference)
Please let us know, when you did these:
- How many lines did you install?
- Did you do rings or radials?
- How old was the wiring in your main house ring?
- Did you put in 10mm/2 cable in the dedicated lines?
- Did you use a separate CU?
- Did you plug your kit into the wall sockets afterwards, or use a power distribution block?
- Was it done by a qualified electrician?
- I'm not being snarcy, but is your hearing ok? (A lot of hifi lovers are of an age where they suffer from hearing problems...)