Wuss. I have 52 sockets in my study. OK, they don't all have something plugged into them and 8 of them are on the UPS, but that's how many there are. And it isn't too many. They're all on one ring.
I think you'll find that Malta is a very much a country, and anyone Maltese would be slightly peeved by your statement.
Yes.
I can see no major reason (except for continental unpolarised supplies) of having the capacitors between live and neutral, and neutral and earth. This would reduce the leakage to negligible proportions. Why don't they do this? Is it to please the continentals?
I'd say the cost of the mini CUs and the extra labour involved would far outweigh the saving in cost of cable over our systems.
And it's not as if you really need that easy access to MCBs etc. If you do, there's something badly wrong with the installation.
But why? The UK system with fuse protection of the appliance etc in the plug allows for much finer tuning of that protection. It might be that there should be a wider range of fuses and types of fuse for plug top use, but that wouldn't be too difficult.
Very, very few people will attempt to heat a full house with fan heaters, etc. And even if they did in a large house with only one ring, even an old rewirable fuse would blow before the wiring got overloaded to danger point.
New house builders will skimp on almost anything - especially at the budget end.
When I bought my present place in the early '70s, I provided one ring per floor and one for the kitchen. And a lighting circuit for each floor. And got a CU with spare ways. Despite being very tight for cash as a first time buyer. But I only actually installed a minimum of sockets and lights at that time - leaving the installation of what I really wanted as and when I planned out and redecorated each room.
Commercial and domestic just ain't the same thing.
Just why would you want a separate CU in the guest bedroom where the likely appliances are a light or two and a clock radio? And perhaps a socket or two to charge the mobile from or plug in a laptop?
Because in the average house it's all too easy to exceed the 5/6 amp limit of a lighting circuit.
... which is entirely the point of using a ring circuit and the basis for diversity.
Owain
More or less, most countries don't have polarised plugs so what is live is up to chance. The filters must be agnostic as far as L/N is concerned.
Shirley you don't mean that's the *only* goal of the larger standards groups? I too have been involved with enough to know that technical excellence is only one part of the decision-making process: political horsetrading and sectional interest between them usually overpower technical issues. The IETF is (or at least has been) an honourable exception - Dave Clark's ringing speech about 'reject[ing] kings, presidents, and voting... value[ing] rough consensus and running code' continues to be a defining *difference* between The IETF Way and the ETSI/IEEE/national-stds-body/industry-association WayOfDoingThings. Few will bless a grossly technically-inferior alternative when a clearly-superior approach is presented; but when, as usual, there are relatively finely-drawn judgments to be made, the political factors and desire to keep everyone at the table more often than not results in a mess of options-and-alternatives-and-profiles all formally 'blessed' by the standard, implemented in potentially incompatible subsets (or 'profiles' as we call them to hide what's going on!).
Stefek
Precisely. That, and most of the rest are wall-warts for stuff that draws milliamps.
My parents' house, built around 1967 is a 4-bed semi of around 90sqm total floor area. The downstairs was almost completely open-plan with the stairs running up the middle and just the hallway door-ed off. There were three single 13A sockets and one FCU for the whole of the downstairs except the kitchen and two more singles (IIRC) in the kitchen. The bedrooms had one single each. They bought it in 1972 and previous occupants had had central heating installed (three radiators downstairs), putting one of the radiators directly over one of the sockets leaving just two.
Cunningly they had choc-blocked a wire into the back of that socket before mounting the radiator and run it outside to a 2-way rewireable CU in the garage.
There is one 30A sockets ring (most of the downstairs sockets are spurs from that), one 15A radial for the FCU (now a socket), two lights, one cooker.
By contrast, when I rewired our 3-bed semi last year I installed three
32A rings (East, West, kitchen) with a total of 28 double and 3 single sockets (IIRC). Most of these are not in use at the moment. If we move the furniture about they may well come into use. Additionally there is a 32A radial, two 16A radials, two 6A lighting circuits and two spare ways. It's interesting how things have progressed :-)Hwyl!
M.
The nature of a SMPSU introduces all sorts of nasty high frequency garbage in terms of both Voltage and current on both L and N. This must be filtered out to reduce the chances of causing problems with other attached equipment. Read the PDF at the link given by Peter and you'll see a fairly simple yet comprehensive explanation.
Hwyl!
M.
Sounds familier...
When we bought this place (built in 1952) it had one 30A power circuit with two sockets in the front room, one in the dining room, two in the kitchen, and four in the whole of the upstairs. (IIRC the home buyers report commented on there being not many electrical outlets - glad I paid money for that - would never have worked that out myself ;-)
Added another 35 sockets since then I would guess!
The filters on the switched mode PSUs...
There are two issues here - direct contact and indirect contact. You are only looking at situation in the case of a direct contact.
You also need to consider the case where a fault in an appliance allow its casework to come into contact with a live feed. This will cause a direct low impedance short to earth. A small change in earth fault loop impedance will affect how long it takes to clear a fault of this nature. For the duration of the fault you have the issue of the touch voltage on the case posing a risk to the user. The higher the loop impedance the higher this voltage can be, and the longer it can be present.
Which in cases where a high impedance earth may be only a couple of ohms that is not the same thing.
Sounds like a recipe for lots of spurious trips though...
Hear, hear.
One thinks of protocols as an example of committee decision making with failed outcome and token ring and WEP of industry attempting to do the same.
I meant OSI protocols of course...
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.