mains block and equipment cable

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Classicrock
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Re: mains block and equipment cable

Unread post by Classicrock » Wed Jan 03, 2018 6:23 pm

Dr Bunsen Honeydew wrote:
Wed Jan 03, 2018 4:51 pm
Classicrock wrote:
Wed Jan 03, 2018 12:59 pm
Something worth noting concerning ring mains. All depends what you plug into them - too much stuff permanently plugged in (non hi-fi). I believe if you don't overload and properly installed OK. It appears it is mostly badly made fridges and tumble driers that cause fires. Grenfell Tower not caused by cladding but a fridge. Logic is they should be panicking more about fridges. Obviously a dedicated radial will aid Hi-fi sound if it is practical and all those fuses can't help. I use the cheapest cheapo mains blocks which have no fuse and neon light.
The problem with a ring is they do not fail safe, if a wire is loose or disconnected it still works but the cable one way in the ring is being overloaded and can flame.

Go to https://en.wikipedia.org/wiki/Ring_circuit and read criticism.
I go round and check the connections on every socket. I have found sockets were metal box isn't earthed. Will eventually replace all sockets in this house but will get it tested and new consumer unit installed. More expense after re-tiling/felting a huge roof, replacing windows. About to start on rebuilding rear extension/ conservatory plus kitchen and bathroom(s) to do all of which will involve some rewiring. Sounds like the problems are not the design but installers and occupants messing with wiring. Running radials to every socket is pretty messy and awkward especially in modern building with solid ground floors. Do you seriously think continental installations are in practice safer in France, Spain italy etc? In Germany almost certainly I would think. If you have looked at recent TV progs on rental properties /council inspections it is no surprise they are going up in flames. Especially some of those east europeans plugging a continental two pin plug into a UK 3 pin socket. The problem is usually stupid or corrupt people. Not to mention people bypassing the metres or connecting to a neighbours. Would explain the stats you keep quoting. Similar to twats who insist on moding hi-fi themselves :lol: Also remember when ring main was introduced there wasn't the demand for so many sockets to plug in all the tech crap people are using today. The problem for hi-fi is isolating it from all the other stuff being dumped on the mains. Not something that logically fancy mains cable will address to a significant degree.

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Dr Bunsen Honeydew
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Re: mains block and equipment cable

Unread post by Dr Bunsen Honeydew » Wed Jan 03, 2018 6:52 pm

It seems you don't understand Radial circuits, each socket is not wired separately, they are wired as a line.

This is a wiring instruction from a supplier to electrical installers.

Two types of radial circuit are permitted for socket outlets. In neither case is the number of sockets to be supplied specified, so the number will be subject to the constraints of load and diversity. The two standard circuits are:

1. - 20 A fuse or miniature circuit breaker protection with 2.5 mm² live and 1.5mm² protective conductors (or 1.5 mm² if m.i. cable) feeding a floor area of not more than 50 m². If the circuit feeds a kitchen or utility room, it must be remembered that a 3 kW device such as a washing machine or a tumble dryer takes 12.5 A at 240 V and that this leaves little capacity for the rest of the sockets.

2. - 32 A cartridge fuse to B888 or miniature circuit breaker feeding through 4 mm² live and 2.5 mm² protective conductors (or 2.5 mm² and 1.5 mm² if m.i. Cable) to supply a floor area no greater than 75m².

4mm² may seem to be a large cable size in a circuit feeding 13 A sockets. It must be remembered, however, that the 2.5 mm² ring circuit allows current to be fed both ways round the ring, so that two conductors are effectively in parallel, whereas the 4 mm² cable in a radial circuit must carry all the current.

Radial circuits can be especially economic in a long building where the completion of a ring to the far end could effectively double the length of cable used.

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Re: mains block and equipment cable

Unread post by Dr Bunsen Honeydew » Wed Jan 03, 2018 7:06 pm

There was a fad a while back, because of the the health concerns of Ring Circuits and the fields they create, of breaking the ring (and obviousy insulating the ends) at the point of equal load on each side, and running them as two parallel Radial Circuits.

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Re: mains block and equipment cable

Unread post by Dr Bunsen Honeydew » Wed Jan 03, 2018 7:46 pm

Another foreign view of our stoopidity.

Ring Circuits
In some countries (e.g. the U.K.) it is legal to connect a series of electrical sockets in a wired “ring.” Using this method, a connection to the power source is made at two points of the ring (the “ends”).

Ring Circuit can create EMF

The live and neutral wires each form a ring, and both wiring rings follow the same physical route. But live current could take the path to a socket from one end of the ring, while neutral current could return from the socket to the other end.

This can happen if there is a bad connection or other resistance at some point in one circuit, or by using poor quality or damaged cable, as electricity will always flow through the circuit offering the least resistance.

The net imbalance between live and neutral current flow in parts of the circuit causes an EMF, so ring circuits can generate strong unwanted magnetic fields.

The alternative to a ring circuit is to use a branched /radial wiring circuit.

In a branched or radial circuit the live and neutral wires are connected to the power source at one end only, and terminate at the last socket in the circuit. The live current can take only one path – likewise the neutral current. Live and neutral current flows are always in balance, so no EMF is created.

Ring wiring circuits can generally be converted to radial circuits without large expense, but this is a job for a qualified electrician.

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Classicrock
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Re: mains block and equipment cable

Unread post by Classicrock » Wed Jan 03, 2018 10:14 pm

Dr Bunsen Honeydew wrote:
Wed Jan 03, 2018 6:52 pm
It seems you don't understand Radial circuits, each socket is not wired separately, they are wired as a line.

This is a wiring instruction from a supplier to electrical installers.

Two types of radial circuit are permitted for socket outlets. In neither case is the number of sockets to be supplied specified, so the number will be subject to the constraints of load and diversity. The two standard circuits are:

1. - 20 A fuse or miniature circuit breaker protection with 2.5 mm² live and 1.5mm² protective conductors (or 1.5 mm² if m.i. cable) feeding a floor area of not more than 50 m². If the circuit feeds a kitchen or utility room, it must be remembered that a 3 kW device such as a washing machine or a tumble dryer takes 12.5 A at 240 V and that this leaves little capacity for the rest of the sockets.

2. - 32 A cartridge fuse to B888 or miniature circuit breaker feeding through 4 mm² live and 2.5 mm² protective conductors (or 2.5 mm² and 1.5 mm² if m.i. Cable) to supply a floor area no greater than 75m².

4mm² may seem to be a large cable size in a circuit feeding 13 A sockets. It must be remembered, however, that the 2.5 mm² ring circuit allows current to be fed both ways round the ring, so that two conductors are effectively in parallel, whereas the 4 mm² cable in a radial circuit must carry all the current.

Radial circuits can be especially economic in a long building where the completion of a ring to the far end could effectively double the length of cable used.
Fair enough but thought you were limited to a couple of twin outlets similar to a spur. I do have a radial to the garage but of course square pin sockets. Cooker outlets are of course radial with a single outlet. I had to persuade an electrician to reconnect the oven to an unused cooker radial in my last house. He reconned wiring into a ring was OK. Just shows confusion in trade with the regulations.

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Re: mains block and equipment cable

Unread post by Simon Hickie » Thu Jan 04, 2018 12:18 pm

Dr Bunsen Honeydew wrote:
Wed Jan 03, 2018 6:52 pm


2. - 32 A cartridge fuse to B888 or miniature circuit breaker feeding through 4 mm² live and 2.5 mm² protective conductors (or 2.5 mm² and 1.5 mm² if m.i. Cable) to supply a floor area no greater than 75m².

The ground floor where the hifi is 110m sq, has four reception rooms, kitchen, utility, etc. Might this be a bit much for a radial circuit? Sounds like I might need 6mm wiring but that might be a pig to install. That said, we do not run a huge amount in each room.
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

Berty bass
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Re: mains block and equipment cable

Unread post by Berty bass » Thu Jan 04, 2018 12:37 pm

Could you feed a radial circuit to one room on a floor only - eg a dedicated music room or living room where your set-up is - or does it have to feed the whole floor?

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Re: mains block and equipment cable

Unread post by Geoff.R.G » Thu Jan 04, 2018 12:48 pm

Berty bass wrote:
Thu Jan 04, 2018 12:37 pm
Could you feed a radial circuit to one room on a floor only - eg a dedicated music room or living room where your set-up is - or does it have to feed the whole floor?
Yes, I have one for an electric "fire", one for a cooker and the rest of the ground floor is on a ring. That was the way the house was built.

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Re: mains block and equipment cable

Unread post by Geoff.R.G » Thu Jan 04, 2018 12:57 pm

Quarknosis wrote:
Wed Jan 03, 2018 1:14 pm
I wonder how many cables can be wired into a standard plug? Obviously it depends on the size of the cable but if it could be done it would take the extension block out of the equation and reduce the amount of connections needed.

I have used one of those 4 way plugs in the past but can't say that I noticed any difference at the time.
Given that the square pins on a standard UK 13A plug actually have a relatively small contact area with the socket I wouldn't want to have several devices attached to one plug. A 15A round pin plug has a greater contact area. The best answer, have a radial installed and terminate it in one or two 15A sockets. Connect a 15A plug to a separate distribution box and connect all/some of your devices to that. You would be well advised to check the regulations and buy an appropriate distribution box (Terminal block).

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Re: mains block and equipment cable

Unread post by Dr Bunsen Honeydew » Thu Jan 04, 2018 1:15 pm

Simon Hickie wrote:
Thu Jan 04, 2018 12:18 pm
Dr Bunsen Honeydew wrote:
Wed Jan 03, 2018 6:52 pm


2. - 32 A cartridge fuse to B888 or miniature circuit breaker feeding through 4 mm² live and 2.5 mm² protective conductors (or 2.5 mm² and 1.5 mm² if m.i. Cable) to supply a floor area no greater than 75m².

The ground floor where the hifi is 110m sq, has four reception rooms, kitchen, utility, etc. Might this be a bit much for a radial circuit? Sounds like I might need 6mm wiring but that might be a pig to install. That said, we do not run a huge amount in each room.
You will certainly have more than one ring supplying that area so it will be the same with Radial.

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