Here in the U.S., voltage is served up to homes as 120/240 volts, basically the secondary of a 240 volt, center-tapped transformer. 120 volts is used primarily for the normal "plug-in" appliances, such as stereos, toasters, fans, waffle irons and computers as well as the home's lighting circuits. These circuits are balanced on both sides of the transformer's secondary. The 240 volts taken across the "outside legs" of the transformer is used for higher-power applications where the doubling of voltage halves the current requirements over that of 120 volts for a given power consumption. So, 240 volts runs our water heaters, air conditioning, electric heat, electric clothes dryers, arc welders and cooking stoves.

To say that the wiring practices in the U.S. leaves a lot to be desired (citing Norm the carpenter vs. Chico the electrician is a little foolish, don't you think?) is a bit inaccurate considering the awesome territory covered by the NFPA's National Electrical Code. The weakness is that the code is only required by the municipalities that adopt it as a standard. When wiring outside of these geopolitical boundaries, adhereance to the Code is not a requirement, although if some liability lawsuit erupts resulting from some electrical malfuction, you can bet that the Code will be cited and will be the standard against which the case may be resolved, requirement or not.

In our area, it is common for a home outside one of these geopolitical boundaries to be built by carpenters, wired by carpenters, plumbed by carpenters, painted by carpenters, etc. and I'll admit to having seen some stupid things done.

So the real problem is that the NEC is not a National standard. On the other hand, it means that I can replace a bad light switch myself for half a dollar rather than having to hire a licensed electrician to do the job for fifty dollars or more. MAYBE it's safer in Australia and the U.K. because of that, but is sure makes simple home maintenance a bit pricey, doesn't it?

In general, though, any industry will use licensed electricians and follow the NEC very closely while homes located in "the sticks" often will not.

The NEC does have some weak points that I don't like. For instance, it varies the "rules" depending upon whether the home is "site-built" vs. a mobile home or "modular" home or a recreational vehicle. The actual wiring practices allowed in a mobile home are overall substandard over those of the site-built home in most cases. But in one case, the mobile home have a safer installation when it comes to electric clothes dryers and electric cooking stoves. In site-built homes, only three wires are required for these appliances: two hots and the neutral. In mobile, they require four, adding a safety earth ground connection to the frame of the appliance, which only makes sense considering that these appliances are all operated within reach of earth grounds available through plumbing.

Dean

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Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

 

That's one of the problems with the size of the USA!, but one of my main concerns is the plastic 'nuts' (historically called 'screw-it connectors in the UK) - which seem in use in all the TV programs you see (and Steve and Norm travel round many different states). These were declared illegal and banned back in the 1960's in the UK - they don't strike me as a very safe practice?.

Other things which come over in TV shows is things like light fittings?, some of those you see being fitted would be banned from sale in the UK as unsafe, and any which had sneaked out would be subject to a safety recall.

No, at least in the UK, you are perfectly free to do your own maintenance.

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Really? Being an electrical engineer I must say technically they offer the best electrical connection method(other than soldering and crimping) as the wires are twisted into helix by the plastic screw on nut and then insulated. The nut will not fall off unless someone twist and undo it.

The proper way is not to twist the wire ends before applying the nut. If you twist the ends, the nut would not be securely stay on the joint. I think this is the main reason these are banned as most people are not aware of this gotcha.

Applied correctly I think it is much safer than just twisting the wire ends together by hand and apply several covers of PVC insulating tape. Some insulation tape on joints would unwound itself after some years.

But regulation is still regulation and all(in uk) must observe. Don't try it.

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L.Chung

 

As you are an "electrical engineer" I'm amazed to hear you say that?, the plastic in the nuts will age and may well crack over the years, and thermal expansion and contraction can make the nut become loose.

You also appear to be totally ignoring the accepted way in electrical wiring in the UK, which uses brass connectors and brass screws, in insulated housings.

Interesting idea?, but ALL the TV footage I've ever seen from the USA where they fit these show them twisting them together FIRST - and in fact making a point of telling you to make sure you twist the wires the correct way.

I certainly NEVER suggested that!, and no one should EVER do such a thing! - certainly plastic nuts are a step up from that type of bodge!.

Yes, you need to conform to regulations, to a certain extent! - any new work most comply, but there's no regulation requiring old installations to be upgraded to new regulations.

For a horror story! - I've seen lead wiring still in use!, this uses a lead outer sheathing (used as the earth conductor), with the two copper wires inside insulated by linen cloth! - as you can imagine, the linen perishes over the years (and it's all MANY years old now), leaving no insulation!.

Also dangerous is the old rubber covered cable, although not as old as the lead, the rubber crumbles away leaving bare wires.

I'm not sure when lead and rubber stopped being used, but it's a LONG time ago, and there can't be much of it left!.

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Not any more after coming to live in the UK.

Never seen one. Perhaps others would put in their experience.

You are referring to Wiring Practice in UK which applies to wirings of fixed installation which I'm not. My view point is just simply connecting a wire say inside an amplifier project box.

I never said one should use the "nuts" to replace the acceptable method of wire jointing. I just said technically it is better than just twist the wires together and apply a few cloth of PVC insulating tape. If Nigel you have ever jointed wires before, tell us that you have never twisted two wires together and apply PVC tape but always use the "proper brass connectors" method instead.

The only reason I can think of old installations not being upgraded is such act would create too much hardship for the owners. Not that the regulation should not be conform to the full.

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L.Chung

 

Not in this century! :lol:

And NEVER for mains installation wiring, which is what the thread is about.

Do you remember the fabric based insulating tape? - horrible stuff, used to be popular before PVC.

The obvious reason is cost, it's an expensive job to rip out and replace all the wiring, although it's got the obvious advantages of adding extra sockets when you do it. A lot of the houses with old wiring are lived in by very old people, who can't afford (and don't have) the money.

One thing I have noticed about the American DIY programs, apparently (depending on the state?) you have to fit mains sockets every so many feet? - I don't know if such a regulation exists in the UK?, but I've never heard of it? - good idea though!.

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Not any more! As of january this year (2005 for any one who reads this in 2045), any electrical work done in the home needs to be done by a certified engineer and a certificate issued. It is not against the law the do the wireing in your own home, but it is illegal to try to sell your home if any electical work was not performed by a certified engineer. The new laws are petty at the best, but alas, I will spare the potitical side.

 

Oh, I thought we are talking about those Ads we saw on TVs.

If someone is doing my installation wiring, I would not accept even a "brass connection with insulator" and demanded a whole length of fully insulated cable instead.

To your surprise they are still being use a lot to cover the sharp edges of high voltage electrical joints before applying PVC insulation tapes to cover the whole joint.

Isn't the word "hardship" means approximately the same thing?

That's would be classified as good wiring practices but I'm not sure the regulation would make fitting them mandatory.

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L.Chung

 

I'm not talking about simply extending a piece of cable, but how ALL the connections are made in a house - in light fittings, junction boxes for two way switching - anything which needs a connection.

However, there certainly are occasions when you might want to extend a piece of cable - for example to move a switch or socket, when replacing the entire cable would involve ripping loads of plaster off. But for a new installation, there shouldn't be any reason.

Mind you!, it doesn't stop the Electricity Board people doing so in the road!. Near where I work we keep getting repeated failures in an underground cable - it must now have joins every couple of feet for 5 or 6 yards!.

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In many countries, wiring regulations and codes specifically do not apply to power generating company. Inside a power plant, many live conductors are exposed.

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L.Chung

 

That's would be classified as good wiring practices but I'm not sure the regulation would make fitting them mandatory.[/quote]

I think the code on this item applies to new construction, and it is SAFETY related more than convenience related.
Reasoning: Majority of home fires can be traced back to overloaded extension cords. I think the code is (don't quote me on the exact fugures) that an outlet should be placed so that the max distance between any 2 adjacent outlets is 12 feet or less. If you look at appliance cords, most are around 5-6 feet in length. Using this logic, placement of the appliance should result in the appliance cord reaching an outlet without the need to use an extension cord. And it is darn handy to boot. This item is one of those that is good safety practice and makes a heck of a lot of sense also.

On a side note, I cannot understand the resistance to using the twist on wire connectors. I have seen circuits 20-25 years old that are in perfect condition using these devices. The main thing is the quality of the device used. The hard plastic ones (bakelite exterior) ARE prone to breaking, but most likely if someone uses an improper tool to install it (ie. pliers). The best are the soft plastic exterior with a locking helical spring interior (Scotch Locks).

This is one of those times when the old saying of "You get what you pay for" or "Penny wise, Pound foolish (imported saying from across the big pond)" applies.

Dialtone

 

Yes of course, you can't very easily force everyone to upgrade existing installations.

In the UK there's a restriction on how close you may have sockets connected on different phases (where you can get 440V between phases). The standard length of UK mains leads is designed so you can't handle an appliance from each phase at the same time - obviously extension leads soon mess that idea up though!. However, domestic premises wouldn't normally have more than one phase available.

It's perhaps a thing with our higher mains voltage?, but they have been banned from use in the UK for 40 odd years?.

I've only ever fitted TWO - they were in a Heathkit FM Tuner kit I assembled for someone a long time ago - beautiful things Heathkits :lol:

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I hope your local electricity distributor isn't using brass screw-terminals and insulating tape :wink: they will be using a system similar to "ScotchCast" joints - these end up just as good as (or better than) the cable they are jointing.

The UK rule book is called the "IEE Wiring Regulations", we are on the 16th edition at the minute. I remember decades ago they never applied in our Power Stations, the CEGB had their own standards but now with "de-regulation" (thanks for nothing, Thatcher!) the 'Regs' apply to all UK power wiring - it just gets very vague at 132kV or 6000A.
The only bare live conductors are those out of reach -the swithcing compound (like a private substation) - these conductors are high above head-height on insulated supports, they take the cables going out onto the pylons (400kV).

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I need a memory upgrade ...
My head is full !

 

I don't know what it's called, but they incapsulate it in some kind of epoxy, because they leave the boxes behind it comes in - about the size of a large lunch box.

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