Comments by "John Burns" (@johnburns4017) on "Technology Connections"
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@quagsir-behattedbloboftheu5051
This is applicable to radial and ring circuits. Do the 1st fix using lever Wagos type of connectors inside the socket/receptical backboxes, connecting up a ring (or a radial), and even connecting the earth terminal of a metal backbox. The current of the ring only runs thru the ring's cable not via terminal on teh back of sockets/recepitcals. The backboxes are then effectively doubled up as junction boxes. The ring circuit is tested after the 1st fix. Any wiring problems are identified before finishing trades turn up. Putting it right afterwards may be big problems.
Then the plasterers and painters come in doing their work. The Wagos are left in place in the backboxes. Then on the 2nd fix, on a bench the sockets/recepticals are prepared, by screwing into all the socket's tail's flexible 2.5mm cable, including an insulated earth wire, about four inches long with a ferrule onto the flexible wire into sockets screwed terminal connection. The flexible tails are put into the Wagos at the back of the back boxes. The socket easily pushes back in being on flex tails. Then test again. The speed, and ease, of installation is much quicker. And much safer as the ring itself does not have screw connections that can work loose.
I have found many terminal screws on the back of sockets/recepticals that have worked loose over time - expansion-contraction, vibration from people walking on wooden floors, plugs being rammed in and out constantly, etc. That is why screwed terminal are maintenance terminals. Wago screwless are maintenance free. Wago also apply the correct torque to the wire, which is maintained over time as well. Having the full current of a ring or radial circuit flowing through the terminal at the rear of sockets is a potential fire situation, with maybe arcing, also adding higher resistances to the radial or ring, which may cause one leg of a ring to take most of the load, etc.
That is where Wago types of connectors, in the scenario I just outlined, take the ring's load, not the screwed terminals on the rear of the sockets. It is much safer. The sockets/recepticals are only spurs off the ring, taking only current when an appliance is drawing current. Go back to a ring circuit after 10, 15, 20 years, then test it. Then go back to one which has the ring running though maintenance free Wago types. The integrity of the Wago connection ring will be upheld. Much safer.
Having Wago types of terminal connections on the rear of sockets/recepticals, as in Germany and France, adds another level of safety, in eliminating another potential failure/fire risk of the screw terminal . The UK is just introducing these types of socket/receptical connections.
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The comments on UK Ring Circuits (sometimes called Ring Mains) for socket outlets shows great ignorance. Plug-in portable domestic appliances in the UK cannot draw more than 13A (approx 3kW) as the plug has a maximum of a 13A fuse - can be less right down to 1A, depending on the appliance. Subsequently washing machines, dishwashers, etc are limited to 13A - most draw far less. The rings were designed during WW2 anticipating the post war construction boom, being limited to 32A on the ring. A ring takes less cable than a number of radials and less breakers at the main panel. One ring can replace four or five radial circuits.
The 13A fuse in the plug is specifically designed for rings. In the UK you do not have to use rings, nothing says you have to. Many install radials, but the appliance off the ring is still limited to the 13A plug. If you say want a 16A appliance (usually brought in by an individual), it has to be a permanently fixed, not using a plug. A ring also can be installed in any country.
One down side of a ring is that if the two cables forming the ring on the rear of a socket become loose, as the screws loosen over time (expansion-contraction). The current may be sent predominately down one cable (one side of the ring) with a max rating of 27A on a 32A ring circuit. The use of push in Wago service free, screwless connectors eliminates this problem, making rings even more attractive. Germany now is selling sockets that have push in connectors behind - expected in the UK soon. This means that apart from the main panel's breakers, no screwed wire connections are used. Many electrical fires are because of loose connections.
Rings are only generally feasible when the plugs and spurs off them used have fuses. In the UK the plugs ensures rings are safe.
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@billelkins994 wrote:
"In recent years the British standard for new ring installations requires a wire size equivalent to a radial run so the ring's big advantage of using smaller wire is no more."
Nonsense, you made that up.
Many clearly do not understand what a final ring circuit is. The ultimate system is to have a radial circuit to each socket outlet on its own fuse at the main panel - the optimum solution of course. This means you will need a very large expensive main panel and lots of fuses/MCBs (one for each socket) in the main panel. Impractical of course.
🎊🎈 BINGO 🎊🎈
A ring gives this by distributing the main panel around the house via a ring cable, distributing the fuses from the main panel around the building to each socket. The ring is a busbar. This saves the vast expense of a plethora of radial cables back to the main panel and also a plethora of expensive fuses/MCB's/RCBO/AFDDs at a very large expensive main panel and expensive labour to install.
a) A ring uses less cable and gives a longer route.
b) No limit to sockets on the ring, but total is limited to typically 32A.
c) A ring uses less copper for a given load/area.
d) Rings rarely have voltage drop as it is fed from both ends.
e) Rings have lower impedance, less volt drop is less waste! They are more efficient.
f) No single point of failure for the protective earth.
g) If you are covering all rooms in one floor then a ring can do it.
h) An appliance and its flexible cable may have a fuse sized to its rating inside its plug.
1. Ring final 2.5mm cable, 32A B-curve MCB, length 106m on TN-C-S.
2. Ring final 4mm cable, 32A B-curve MCB, length 171m.
3. Radial final 2.5mm cable, 25A B-curve MCB, length 33m.
4. Radial final circuit, 4mm cable, 32A B-curve MCB, length 43m.
If a ring is in 4mm cable protected by a 32A MCB/RCBO, then no problems if the cable is broken - which is a very rare thing. The ring can be partially 4mm to heavy current appliance sockets and 2.5mm for the rest
The ring final circuit is safe, simple, and highly effective after 80 years of use. The introduction of MCBs/RCBOs/RCDs/AFDDs, and Wagos on the ring, has made the ring even safer.
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Yes, there are advantages to the British final ring circuit. They have been widespread in the UK for 80 years. They have been found to be very safe.
♦ Cheapness, as smaller, easier to install, wires can be used;
♦ Two ways for the earth back to the consumer unit;
♦ Another is a large number of sockets can be off one cheap ring;
♦ Having the same number of sockets using radials would mean multiple radials and multiple extra expensive breakers at the main panel - MCBs/RCBOs/AFDDs. Far more cable, expense, labour and hassle;
♦ The 32A breaker and 13A fuse in the plug ensures safety.
♦ Portable plug-in appliances on a ring cannot exceed approx 3kW. Some plug-in ovens are on rings;
♦ Rings usually have a 32A breaker at the main panel - can be a smaller value;
♦ Using push-fit maintenance free Wago type connectors to connect up the ring makes them a lot safer as not being screwed connections they do not work loose. The ring's current does not run through the socket terminals;
♦ The British plugs are designed with rings in mind having a max 13A fuse in them - can be as low as a 1A fuse in the plug to suit the appliance. Small flex and appliance? Then a smaller fuse;
♦ Rings in the UK are limited by square metres of floor space, with no limit to the number of sockets on the ring. 100 square metres of floor space for 2.5mm cable for a 32 amp protected final ring .
Radials are also used in the UK. Rings are not mandatory, but used because they are generally trouble free and safe. They can be installed using rule-of-thumb. These days a ring will be on an RCD or RCBO - RCBOs now are becoming double pole so safer again. In one job in an office, they wanted more socket outlets for extra desk computers. It was a simple matter of extending the existing ring with the extra sockets as the current draw was low. Also no vopltageb drop as the socket outlets are fed from two directions. Cheap and easy. If radials were used three radial circuits would be needed, which would mean an extra main panel, breakers, wire, etc, then far more labour.
Some disadvantages are:
♦ Rings are more difficult to fault find. But electricians have no problem once the ring is fully understood. Instrumenet are avaikable test them;
♦ Another is that if a number of high current drawing appliances are on one side of the ring, say near to the main panel, most of the current draw may be down one leg of the ring which is rated below the main 32A breaker. 2.5mm cable is rated at 27A max. Although tests have proven the cables do not exceed their current capacity, just an imbalance in distribution of the two cables from the main panel (consumer unit). Good circuit design will prevent this, negating this disadvantage. Balanced rings can be installed by daisy chaining to alternative socket outlets on the ring. That is the first socket will draw from one side of the ring, the second socket will draw from the other side, and so on round-robin. Or use 4mm cable to the point where heavy current drawing appliances are, then 2.5mm for the rest, if it is that troubling for some. Using 4mm cable on one side of a ring and 2.5mm on the other, is still cheaper than a bunch of radial circuits.
Overall I consider one ring superior to a bunch of radials needing their own breakers at the main panel. They are simpler, cheaper, being proven to be safe and worked well over the past 80 years. You will have to give a very convincing argument for me to give up rings. I have not heard of one yet.
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