110V ac

No, they hoped that most of you "Loyal British subjects" would quickly electrocute yourself, and they wouldn't have to wire as many homes. Also, if copper was a problem, we couldn't have used more of it could we?

Different design requirements. Run the primary close to a house, or a couple houses, put up a transformer and have short runs to a home work very well here. It also makes it easy to add to the system, or change the configuration for special applications.

Of course, you'll still believe that your slow (50 Hz) system is better, no matter what evidence you see. :)

Local code requires the meter and main disconnect to be away from the house in case of an emergency, but a lot of homes are underground to a short pole with the meter and switch, then underground to the house. My subdivision is overdue a complete rebuild. It was laid out in 1964, all overhead along the street, and either overhead or underground to the homes. The worst part is is was built for 60 amp 220 volt service and most homes have 150 or 200 amp service. Friday evening about 4:45 PM a fuse in a 7200 volt line blows when everyone gets home from work and fires up the central air, electric stove and all their other toys.

Holly Park neighborhood of San Francisco. It was built in 1892 (we think), mostly redwood, and originally had gas lighting, then horrible knob-and-tube wiring, then conduit (that was mandatory for a time, still is for commercial buildings), finally Romex. I cleaned it up a lot.

We now live in a new house, built in 1992. It's amazing: everything works, and there's 15 amps at every outlet. All I had to do was put in some dimmers. The street wiring is underground, but much of the city still has overhead wiring with the occasional "pole pig" (stepdown transformer) up on the poles, too. They're gradually undergrounding everything, but it's very expensive and may take decades to complete. They are just now tearing up my street to replace all the old gas lines with high-pressure (75 psi) plastic tubes, which they can push inside of the old rusty low-pressure pipes.

Here in California, houses are almost always made of wood over a concrete foundation. That combination handles earthquakes very well.

Where are you? What's the house made of? I've seen lots of stone in the UK. Quaint, as long as the ground doesn't shake.

It's interesting to compare wiring in the US to the UK. We have one-way runs of 120 volts, wire-nut junctions, push-in-wiring outlets, plastic junction boxes, small plugs, GFDs only in wet areas. You have (I think) ring-wired 240, screw terminal blocks, master GFDs, huge plugs with fuses inside.

John

That sounds entertaining !

How common is 'power off the pole' in the US ?

We only see it here in the UK in remote rural areas.

Incidentally, your house must be around the same age as mine - 113 yrs old here. Whereabouts is that ?

Graham

Do fusebox GFD's false-trip a lot? We have them in outlets in the kitchen, bathrooms, and garage, anywhere potentially wet, and certain brush-motor-type appliances tend to trip them; slows me down grinding coffee sometimes. Sometimes they just trip, probably from transients somewhere.

I measured 5 megs leakage on my garbage disposal, and that was enough to trip a GFD. I also had a sump pump (the lower level of my house is below the street, so we have to pump stuff up from the lower bathroom) that tripped its GFD from a tiny bit of leakage.

John

Single once-upon-a-time-insulated wires, about a foot apart. They go through studs and rafters through drilled holes with ceramic tubes inserted, and can angle off a sort of stack of two ceramic cylinders with a nail through the middle. Joints are twisted and taped; no junction boxes. Fire waiting to happen.

The Big One was 1906; 9.0 roughly. Half the city was destroyed, a few thousand killed. There's a wonderful Irish pub near work that has a clock stopped at 5:15 (AM) which they swear fell and broke in the 06 quake. Guiness, Harp, and Widmer on tap, free popcorn, so we accept the story.

The Pretty Big One was 1989, 7.2, about 80 killed. A few apartment buildings in the Marina neighborhood collapsed, a combination of weak ground floors (garages) and soil liquefaction (built on bay fill from an old World's Fair.) But the deaths were from a freeway collapse and brick buildings. The 89 quake took out two brick chimneys in my old Victorian, leaving holes in the ceiling, now skylights. Our new house has a massive reinforced concrete foundation, shear walls galore, and steel structures in the front and back where it's weakest from the garage door and windows and stuff.

when it

conveniently

We love London, especially the north part, Hampstead Heath and all that. But then, I don't know too much about the rest. Spent some time in Oxford last spring... very nice. It did scare me, though, earthquake-wise; it'll be a pile of Oxford-shaped rocks if anything happens.

John

I read in sci.electronics.design that John Larkin wrote (in ) about '110V ac', on Fri, 11 Feb 2005:

It sounds as though you have voltage-sensing devices. In Europe we now have differential current-sensing devices - Residual Current Circuit Breakers - with controlled operating currents, such as 10 mA and 30 mA. The latter are normally used, ad protect very well against life- endangering shock while minimising nuisance tripping.

IIRC the American GFI is a 5mA sensitivity device! Talk about a world of pain!

Modern UK practice is to use a 'split load' consumer unit with the lighting circuits connected before the RCD (possibly also any dedicated circuit for a fridge or freezer), with most of the sockets connected to the RCD protected side.

However RCDs are only REQUIRED where circuits are likely to be used outdoors or where other special hazards exist. Everywhere else they are optional (but strongly recommended).

My setup uses combined RCD/overload trips (known as RCBOs) rather then a split load system because I did not want all the sockets failing due to a fault in one room. The incoming supply is also fed thru a 100mA time delay RCD for fire protection.

Regards, Dan.

here.

Same build date here. Evidence of former gas lighting too.

I have no idea when electricity was added but there a few remnants of old rubber insulated wiring if you look around under the floorboards. Amazingly, last time I looked, the rubber was still unperished !

I don't know what 'knob and tube ' wiring is - do you have a link or something ?

In towns / cities here - overhead mains wiring is unknown. I do still have an overhead telephone line from a pole though and a second underground one from a cable company - just for diversity :-).

Ah yes - popular tactic is to push modern plastic pipes inside the old stuff here too. I think they may be doing that with water now too. The infrastructure is getting old.

Sensible move, although I seem to recall a number of Victorian style houses collapsing during the San Francisco ? quake of when ? several decades back ? Foundations in that area maybe not up to it ?

St Albans - about 20 mi N of London. City history dates back to Roman times when it was called Verulamium.

Just far enough out of London to get away from the mad city thing but conveniently placed to visit when you want to indulge.

Classic brick built. Very typical of Victorian houses. One of the end houses of a terrace of four.

Not much stone round here generally. Aside from the cathedral. Even that is something of a mixture of styles and build materials since it dates from Norman times.

Ring wiring is a neat idea, although for reasons related to its former role as a rented accomadation, my property actually has 4 x 30 A spurs ( plus lighting circuits of course ). The ancient 'panel' hasn't a breaker in sight but arrays of good old fashioned fuses - some of which are replaceable wire link types !

That idea of fusing the plugs never caught on worldwide. And yes - they're pretty robust too. From pics I've seen it looks like Iraq adopted our system, as a curious sidenote.

Cheers, Graham

old here.

I've just bought and moved into a 100 (thereabouts) year old house in Auckland, made of mainly kauri (local hardwood no longer readily obtainable). Fortunate that - the crappy 'remedial' works done on drainage in this place over the years would have destroyed wood of lesser quality! Anyway I've just about finished getting the old wiring out - mainly that conduit-run insulated cabling which has insulation which falls apart long before now, but also later wiring with PVC-like qualities (except for the similar rodent-tasty, crumbly nature of it). Here it's all 240V off the pole (like yours, being undergrounded, but they haven't even started in this older area yet) or 3-phase 415V if required. No fuses in plugs but GFD's are now mandatory in new installations at the fusebox - I've got several in mine so I won't lose everything at once.

Ken

How could a GFD be a voltage sensing device? What voltage would it sense? Every one I ever heard of was a common-mode current transformer.

John

drainage

pole

are

mine

I've guessed that your expression 'GFD' is the same as whatever we use (can't recall name - brain's on holiday today) - false tripping is extremely rare in my experience (with the more modern devices anyway). But it also depends on what you're powering. My wife does glass casting and has a cute mixture of power tools and water in her workshop. The only thing that's ever tripped the protection device was a *very* wet multi-outlet power board. Fair enough too, in my opinion! :-)

Ken

something ?

houses

back ?

times when it

conveniently

New Zealand is known as the 'Shaky Isles' because it's so earthquake zone. Wellington (the capital) is on a fault line - you can see the fault line in the hills as you drive along the motorway into the city. There are buildings which straddle it too! Auckland (where I am) isn't so quake-prone, though it is built within the confines of seven (mainly dormant) volcanoes.....

Ken

No reasonable construction can stand up to a mudslide, any more than a lava flow. Envision a million tons of nearly solid earth and rock coming down a hill at 60 MPH. The sensible thing to do is not live in a slide-prone place.

John