120 and 220?

[bootstrap's_bootstraps]

here where i live (brazil) and europe they use 220-230 volts. in north america it is 120. why do they use different voltages?

 

[mahinda jayasinghe]

I belive it is expensive to maintain 120V electrical network, than 220V network. But 120V is much safer than 220V. USA and other oil rich countries are using 120V sypply.

 

[Morgen]

**broken link removed**
I don't think oil has much to do with it.

 

[williB]

i wouldnt consider us oil rich .
an oil rich country actually HAS oil under their country .
we on the other hand have to purchase it..

 

[Jay.slovak]

here where i live (brazil) and europe they use 220-230 volts. in north america it is 120. why do they use different voltages?

This is just only a historic issue. Back in Edisons and Teslas times, they competed which technology is better (AC or DC), And the voltages didn't chage until novadays.

 

[Styx]

I belive it is expensive to maintain 120V electrical network, than 220V network. But 120V is much safer than 220V. USA and other oil rich countries are using 120V sypply.

The UK is oil rich, we are in the black for oil atm and we use 230V.
just a convention a country chose, the same with the freq

if you look at it UK worked on 240V and EU worked on 220V, we now harmonise at 230V, but hte UK still outputs 240V, its just appliences have a voltage tolerance

 

[Nigel Goodwin]

if you look at it UK worked on 240V and EU worked on 220V, we now harmonise at 230V, but hte UK still outputs 240V, its just appliences have a voltage tolerance

Yes, the UK altered the tolerance figures, everyone else is something like +/- 5% - the UK is something like +7% -3% (these aren't the exact figures, just to give an idea of what was done). This allowed the UK not to make any changes to the infostructure.

BTW, the safety aspects of 120V vs 240V don't make a sensible reason for the difference, as I understand it, deaths by electrocution in the USA are no lower than in 230/240V countries. However, from what I've seen on TV (good old Norm 8) ) the wiring practices in the USA leave a lot to be desired?, so perhaps that makes it higher in the USA?.

 

[Pyroandrew]

The wiring practice have been tightened again recently in the UK. On a death point, the two AC supplies are just as lethal as each other. You only need 120v DC to kill, and 50V AC to kill (at 50Hz). So both have more than enough "overkill" to a good job of polishing off someone.

What is interesting is that around 50Hz is the worst place to have to have it, 60Hz more so. Of equal voltages, 60Hz is more deadly than 50Hz, but they are both smack in the middle of the most dangerous electrical frequency region to humans, make it just 100Hz and you would need about 80V AC to kill, 200Hz about 90V, make it 10Hz and you need about 110V to kill. I don't think that the frequency of the mains was selected on a safety note, just like the voltage wasn't either.

It's all to do with what is the most efficient, only 28% of the energy generated actually makes it to our homes and is used for the intended use (UK figures), so minimising waste is a top priority. Just by making the loss 1% less you would produce 16million tonnes less carbon emissions a year in the UK.

 

[mechie]

Electrifying information

The wiring practice have been tightened again recently in the UK.

And we are to get more confused very soon (so-called harmonisation)
The ancient colour code for our mains cable was :-
. Red =Live
. Black= Neutral
. Green = Earth
and still is for 'installation cables'

BUT we have used
. Brown = Live ( :!: an earthy-sort of colour?)
. Blue = Neutral
. Green/Yellow (stripes) =Earth
for flexible cables for ages now.

And now in the name of politics we are to change our three-phase cable colours :-
Old colours ...
. Red = phase 1
. Blue = phase 2
. Yellow = phase 3
becomes
. Brown = phase 1
. Black = phase 2
. Grey = phase 3
Nobody seems able to explain why - I guess it's just to employ bureaucrats

It's all to do with what is the most efficient, only 28% of the energy generated actually makes it to our homes and is used for the intended use (UK figures), so minimising waste is a top priority. Just by making the loss 1% less you would produce 16million tonnes less carbon emissions a year in the UK.

I'm not sure this isn't a bit misleading - the electricity industry is pretty efficient at transporting electicity, the wasteful bit is generating the stuff.
Both the UK and the US (and everywhere else :?: ) actually transport power at much higher voltages than your domestic 240v anyway.
The UK 'SuperGrid' runs at 400,000 volts (400kv) in order to keep the current as low as practicable - current generates heat, that is where most of the transport loss is.

I agree that only about 30% of the energy is delivered as electricity though - the rest is lost in the power station (depending on type)

http://www.straightdope.com/classics/a3_292.html

I wonder if the likes of Parsons would agree with this article?
http://www-g.eng.cam.ac.uk/125/noflash/1875-1900/parsons.html
Also
http://home.frognet.net/~ejcov/ediswan.html
http://home.frognet.net/~ejcov/alfredswan.html
Not to mention a host of other nationalities

 

[eblc1388]

Re: Electrifying information

Old colours ...
becomes
. Brown = phase 1
. Black = phase 2
. Grey = phase 3
Nobody seems able to explain why - I guess it's just to employ bureaucrats

From the IEE review I read that the reason is to "help" electricians with color blindness who cannot distinguish the old color.

Of course I love the old color. I think the change is totally unrealistic and if color is such an important part of the job and getting it wrong would kill, not oneself but others as well, then electricians should be tested for color blindness.

Why not? Would you like to ride on a plane whose pilot is color blind?

 

[mechie]

Re: Electrifying information

Old colours ...
becomes
. Brown = phase 1
. Black = phase 2
. Grey = phase 3
Nobody seems able to explain why - I guess it's just to employ bureaucrats

From the IEE review I read that the reason is to "help" electricians with color blindness who cannot distinguish the old color.

I can't wait to see matching traffic lights :roll:

 

[JFDuval]

Re: Electrifying information

Hello!

Both the UK and the US (and everywhere else Question ) actually transport power at much higher voltages than your domestic 240v anyway.
The UK 'SuperGrid' runs at 400,000 volts (400kv) in order to keep the current as low as practicable - current generates heat, that is where most of the transport loss is.

Here in Quebec, its 735 000 Volts. Probably this is because electricity is producted far from the cities...

 

[Styx]

Re: Electrifying information

Hello!

Both the UK and the US (and everywhere else Question ) actually transport power at much higher voltages than your domestic 240v anyway.
The UK 'SuperGrid' runs at 400,000 volts (400kv) in order to keep the current as low as practicable - current generates heat, that is where most of the transport loss is.

Here in Quebec, its 735 000 Volts. Probably this is because electricity is producted far from the cities...

Damb!! you must have alot of ceramic/glass disks on yr pylons for that kind on potential, equally your main sub-stations must be fairly big as well

 

[JFDuval]

To this point, I cannot comment. I'm not aware of how big it is in others country. So, for me, what we have is normal

 

[zevon8]

The thing about Hydroelectric power in Quebec, Canada, is that alot of it is generated in the James Bay area, so to get to say Montreal, it is over 1000 kilometers.

Some good info is here:
https://www.hydroquebec.com/visit/virtual_visit/reseau_transport.html

one of the substations is here:
https://www.hydroquebec.com/visit/virtual_visit/poste_radisson.html

100 football fields in size, transfering 6600 MegaWatts.

 

[Dean Huster]

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

 

[Nigel Goodwin]

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.

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.

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?

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

 

[eblc1388]

These (twist on nuts) were declared illegal and banned back in the 1960's in the UK - they don't strike me as a very safe practice?.

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.

 

[Nigel Goodwin]

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.

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.

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.

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.

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.

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!.

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

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!.

 

[eblc1388]

As you are an "electrical engineer" I'm amazed to hear you say that?,

Not any more after coming to live in the UK.

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.

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

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.

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.

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.

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.