Electricity in the U.S

[HSV]

Hi there all 
I'm new to this site and am a recent employee of Peterson Portable Sawmills in New Zealand!  I was born in New Zealand and am from the West Coast of the South Island (the best part of the country!)
Thought I'd better introduce myself before I ask a bunch of difficult questions.  If you want to know anything about me please feel free to ask.

If anyone can help me, I'd really appreciate it.  I'm just doing some research on how electricity works in America.
Here in New Zealand, each home has a 240V power supply to their circuit panel.  I understand the U.S has around 120V and the fuses are generally 15 or 20 amps.

How do you get by that low amperage when you are using powertools and the like?  If you are running a bunch of tools or appliances off the same circuit, do you have to put a new fuse in the circuit panel?
Or do you have to call someone in to take a look (qualified electrician)?  What would happen if you bought a new tool that required 30amp power? 

If anyone can answer any of my questions i would be very greatful!
Glad to be a member of the FF  ;D

[JimBuis]

Welcome HSV!!  I spend most of my time in Japan right now, but am in fact an American.  American houses have 110 and 220.  The voltages may vary somewhat depending upon what community you live in, but basically both voltages are available everywhere.  A 110 breaker would be 10 to 20 amps ordinarily.  However, 30 amps are possible and if it is a 220 circuit such as for central air conditioning, i.e. big enough to cool an entire house with one unit, the breaker would be bigger such as 40 amps.  So part of your information was correct just not complete.  There are lots of guys in the U.S. who have 220 volt arc welders plugged into their home.  Many, many homes have electric ranges and/or electric clothes driers all running on 220 and drawing substantial amperage at or about 30 amps.

New tool requiring 30 amps?  I'd just pick up a 30 amp breaker at the store and plug it in.

Jim

[caryr]

Jim, 110 and 220 is mostly antiquated or a minimum. If you actually measured what most houses have it should be closer to 120/240. I have almost 125/250 which is close to the maximum that should be delivered.

Welcome HSV! We have 240V at our panels as well, usually 200A worth, though some older homes only have a 100A service. I'm looking at a 400A service for my new outbuilding. Only very old homes still have fuses. Most houses have breakers which come in many different amperage ratings. Like Jim said 15 and 20 amp are the most common for 120V,  but for 240V you often find much larger. In my panel at 240V I have 20, 30, 40, 50, 60 and 100A breakers.

I hope this help,

Cary

[woodmills1]

The standard is a 220 wire from the street to the house with each side of the fuse panel powered by one of the hot wires of the 220.  Circiut breakers for 220 will clip to both hot feeds and those for 110 will clip to only one.  Lots of possibilities with this set up.  I have a 50 amp 220 breaker in my main panel in the house and the wire from that runs to the garage where there is another panel on a sheet of plywood.  I have wired in outlets for all of the different 220 and 110 plugs that my machines use.  I can run my table saw in combination with the jointer or the planer but not all three at once.

[JimBuis]

Jim, 110 and 220 is mostly antiquated or a minimum. If you actually measured what most houses have it should be closer to 120/240. I have almost 125/250 which is close to the maximum that should be delivered.
Cary

Having lived in a dozen different states and owned six houses in six states, I can tell you for a fact that the precise amount of voltage varies by community and neighborhood.  There are many variables one being the transformer at the street.  It is an electrical impossibility to state that one voltage is the absolute standard for the nation.  The voltage will vary within a general range of roughly 110-125.

IMHO,
Jim

[DanG]

 :D :D There's enough opinions on this to start a new poll. ;D :D  I've frequently seen it stated as 115/230, too.

Y'all be careful upgrading to a larger breaker.  They are usually sized to match the wire, and the wire is sized according to the intended use.  Putting in too large a breaker can be hazardous.

I have much more stuff riding on a single breaker than I should, but, like Woodmills, I can't use the planer and the table saw at the same time, anyway.

Welcome HSV!  Good to have another Peterson person on board! 8)

[CHARLIE]

Welcome HSV!  It looks like you have your answer and pretty quickly too. ;D  While most of my home voltage is 115V, 15 amp, the dryer and stove run on 220V.  In my shop I have 115V 20 Amp and 220V 30 amp.

[sawguy21]

Anyone know why the North American standard is different from most of the world? We also use 60Hz instead of 50 which is common elsewhere.

[caryr]

Jim, I am not trying to be argumentative, but you are misunderstanding what I mean by  "standard". A standard does not have to be a single value like a second or a meter. It can have a nominal value and an acceptable range that may even by asymmetric. It could even include a clause that would allow existing antiquated systems to be used even though they do not meet the current standard.

In my experience if you have less than 110/220V at the panel under loaded conditions the power company will come out and fix the problem and if you are trying to run motors it is likely a problem.

Dan , the 115/230V comes from what is nominally available at a piece of equipment. The difference (drop) is caused by the resistance in the wires between the load (equipment) and the power source. I tend to slightly oversize things to minimize this drop, but with the current price of copper I may need to rethink that.

Anyone know why the North American standard is different from most of the world? We also use 60Hz instead of 50 which is common elsewhere.

I could post more later if you would like. Right now I've got forest chores a calling.

Cary

[DanG]

  I tend to slightly oversize things to minimize this drop, but with the current price of copper I may need to rethink that.

With the current price of insurance, you might want to rethink that again. ;D :D :D

I intend to oversize everything but the breakers in the new house.  Even on a job that size, the additional cost is less than the deductable on my fire insurance.  Peace of mind, and the safety of my family and belongings is worth much, much more than a little bit of copper.

I was half joshing when I suggested a poll on this subject, but it might be interesting to see how much variation there really is.  Any of you who have digital voltmeters could easily take a reading and post it here.  Might be kinda fun. ;D  If you have to ask how to do it, then you don't need to be messing with it, though.

[HSV]

Wow, I wake up on the other side of the world and see y'all have been hard at it helping me out!  That is awesome.  Everyone at Petersons told me how helpful the people on this forum were and now I know for myself... great guys, thanks!

I didn't think it was as easy as just going out and getting a 30 amp breaker Jim?  I was talking with a guy from a company called Mr Sparkey Electricians in the States and he told me you had to make sure the wiring that feeds into that 20 amp breaker would match a larger one (e.g. 30 amp)?  But if that's something you do, then maybe the 'rule' is more of a guideline.
Yeah, we tend to plug more than we should into one breaker at my place, welder, cut-off saw etc, occasionally we'll get a tripout but nothing major.

Okay, so if you had home wiring like Charlie and only had 15 amp breakers but wanted to run a 30 amp appliance, would most of you just go get a 30 amp breaker?

It's pretty interesting huh?  Would be great to see Dan's suggestion in action and check out the variances.

[Mooseherder]

One thing about our electricity is we pay more so the CEO of Florida Light and Power can receive his 12 million dollar salary.   >:(
Can you say monopoly?

[HSV]

12 million, is that all!?  I'm sure he thinks he needs far more than that to survive. 

Hopefully him and his cronies will get shot down one day like one of our largest monopolies Telecom did yesterday.  They were ruled to open their network to competitors hahaha.  Needless to say, plenty of us in NZ are pretty happy with this fair ruling against the Tele - communists.  :D

[mike_van]

HSV, for that 30 amp breaker, you should have #10 cu wire, for a 20 amp, you need #12  and a 15 amp takes #14.  Thats code here in Ct. -  There are codes on top of codes, but electrical saftey is pretty important.  In 35 years with the utility company, i've seen every variation & violation that could be drempt up, many worked for a while, but eventually, someone's going to pay the piper.

[slowzuki]

Just to chip in for Canada, we have the same split phase 240/120 v system.  Our house is at the end of a distribution network starting about 150 km away so there used to be times our voltage was from 110 to 150 v on the regular outlets.

Typically a north american house has the following 240 v circuits:
50A for kitchen stove although the codes allow wiring only sized for 40 amps continuous for those eyeing the outlet for other use!  I found this out when wanting to try out my plasma cutter.
30A for the dryer
20A, 15A heater circuits, baseboards
60A electric furnace in some places

Our house still has fuses and fuse panels only have 2 spots for 30 and up amp circuits, both are used currently so we really need to install a subpanel to handle any other big circuits.

[simonmeridew]

So to answer HSV's question, Well yes you would go out and  buy a 30 amp breaker, but you would want to know a couple of things first: if you're running a 120 volt circuit, is the wire size  for the length of run adequate...at least 10 guage copper, and if 240 volts, 3 conductor of 12 copper plus ground...not 2 conductors plus ground...ground is not same thing as neutral. Also want to know if enough space on breaker box setup. If not maybe use the narrow single slot 240 volt breakers as an alternate.

We have not brought into the discussion 3 phase power; most houses don't have it available, many commercial and all industrial sites do,...but if you do have it, the 110/115/120/125 question gets interesting. How about 108 volts?
I am not an electrician, but want to be safety conscious

[woodmills1]

I do know voltage can vary,  and it might be due to te fact that the load is constanly changing.  Just think about the massive amounts of things that are switched on and off at any given moment.


But,  I line right up with DanG, never just up grade the breaker with out checking the wires current carring capacity.

When I say I have lotsa plugs hooked up to my 50 amps it means each one of those plugs has the wire sized to handle the load.  Also I know not to try  to draw more than 30 amps total cause the wire feeding the garage, though sized right, wasnt my install an is old.

By the way the insurance tip is worth looking into cause you only need it when you do.

Here in NH the homeowner is allowed to do his own wireing right up to the box and meter.  Not so right next door in Maasach..

[maxelectric]

30 amp tool needs 30 amp circuit.
Don't be messing with larger breakers to solve a tripping prob.
Most of the smaller tools will work on a dedicated 20 amp circuit,
and depending on the amperage of the tool, perhaps a couple
of things going at one time on a circuit.

[scsmith42]

HSV - one thing that may be different between New Zealand and US is that our 240 volt circuit is made up of two 120 volt legs (or split-phase as Slowzuki mentioned), and the amperage is per leg.  Correct me if I'm wrong, but isn't your 240volt power just a single phase - ie a hot an a neutral?, rather than the US aplit phase standard of two hots and a neutral (plus a ground)?

Typically, anything drawing more than 20amps will be designed to run on 240 volts instead of 120.  As a for instance, you rarely see an electric motor in excess of 3hp that is 120V - they are usually 240v (not always, but usually).  So a 20amp 240 volt tool "may" actually be receiving 40 amps of power - 20 amps per leg, versus the same New Zealand tool may require a 40A circuit, since it's only one phase. 

One advantage of the 240V split phase for larger tools is that because the current is being divided between two hot's, instead of just one, you can use smaller wire.  Same benefit as 3 phase, just on a smaller scale.

On the breaker sizing, even if you have several outlets off of the same line, you can get by with a breaker that will only cover the number of tools that you'll be running simultaneously.  So, if I have 80amps of tools plugged into a 120 volt line, but only use 20amps of them at the same time, then a 20amp breaker will work.

All of the comments re making sure that your wiring is adequate for the breaker are right on target.  Like DanG and others, I prefer to oversize my wiring - it doesn't cost that much more and it's cheap insurance.

Most new home electric services are either 200 amp or 400 amp, 240VAC, depending on the size of the home.

All - I believe that Caryr is correct re the national standard is 120 /240, not 110 / 220.  We all still speak in terms of 110/220 (I know that I do), but a friend with the power company corrected me about this several months back, and he indicated that all of the US should be on the 120/240 standard.  Jim is also correct - the voltage will vary depending on where you live.

My panels at the house will run around 122, and at the barn around 118.

Regards,  Scott

PS - Please give my regards to Marama and Rex!

[DanG]

I don't know where this "split phase" term came from, but it is not important unless you work for the power company, or have 3-phase power.  The single phase power that most of us use is a single phase feed.  That mean's that the current alternates from 120v positive to 120v negative, for a total of 240 volts.  To obtain 120 volts, we tap in to one of the "hot legs" and neutral.  The voltage will be zero to 120 positive, or zero to 120 negative.  Your appliance doesn't care which, as the 120 volt difference is what it is looking for.  If we want 240 volts, we simply tap in to both of the hot legs and get a 240 volt difference.

If you don't understand what I just said, please call an electrician whenever you need to make a change or an addition.  This is not something to play around with!

[Don_Papenburg]

So how many of you have 3phase power  ?  I like mine as I can get tools at auctions cheaper.

[RichlandSawyer]

Welcome HSV.

  This is a tough one to answer without lots of charts and graphs. As a general rule power tools wired for 120 volts will not draw more than 20 amps, above 20 amps the manufacturer is supposed to go to 220 volts which would decrease the
amperage. P=I x E   (P=power or watts) (I=current or amps) (E=voltage)  

2400 watts=120v x 20a
2400 watts=220v x 10.91a

A standard US wall outlet is only rated for 15amps, a 20amp receptacle has one of the slots turned sideways.
another little tidbit is according to National Electrical Code any circuit should only be loaded to 80%.
so a 20amp breaker should have nothing plugged in to it that pulls more than 16amps.

The difference between your power and ours is the frequency 50hz versus 60 hz. I have neither the time nor the patience to explain this one here but i can tell you that a motor will draw more amps on 50hz then it does at 60hz.

This whole thing reminds me that someone emailed me recently and wanted to start a post with useful formulas so watch for it coming soon to a forum near you.

DanG, good point, ALWAYS call an electrician. Theres a lot more too it than just throwing in a breaker and pulling some wire.
I have a friend who recently sold their house and before the sale was final i spent a couple days fixing electrical problems. The purchaser had a home inspector go through the house and he found about a dozen electrical issues. They are the things you would find done by most home owners but they arent up to the electrical code standards. example: romex running exposed in basement,  receptacles in the garage are not GFI and are too close to the floor.  The point is most cities only allow a home owner to replace something existing like a broken switch or receptacle but do not allow a home owner to ADD anything new. My friend saved money doing it himself but it ended up costing him more in the end having me fix it later.

Sorry i got side tracked for a minute HSV, again welcome to the forum.

[DanG]

Right on, Richlandsawyer!  I agree with everything you said, especially the part where you said I was right. ;D 8) ;D 8)

I plan to do all my own wiring in the new house, but I carried an IBEW card for 34 years, so I figger I can muddle through.  I will have a fresh copy of the code book at hand, though.  Anybody that has questions about it, should just call a Sparky, though.

[RichlandSawyer]

IBEW well i'll be gosh DanGed!!!

    Card carrying member of Local 347 here, Inside Journeyman Wireman

(gives the secret sparky handshake)

[highpockets]

Why we run 120 volt products is still an amazement to me but someone came up with the idea years ago. As for doing it properly we have to run a circuit to each piece of equipment with the proper sized wire and breaker.  Actually 220 volt single (50 cycle) phase users around the world have to do the same thing if they are doing it properly.  Our problem as you know is that we have to run larger wire.

I have spent some 15 years outside the U.S. and started out as a rig electrician in Algeria.  I like the 50 cycle method generally.  I was not impressed with the switches, plugs, and motor controls I found.