bobelectric

Can anyone clue us (U.S.) On why We became 120/240 volts 60hz. The rest of the planet 240/? 50 hz.

cornishsparks

You guys always make things difficult! just kidding
Do you have 220v two phases in your board, do you connect all your outlets between 120 and neutral and your big stuff between two hots or phases.
Dont quite understand your distribution boards.

BryanMD

There is a lot out there on the web about this. Some is even true.

It stated with Mr Edison and his 120V DC system which was overtaken by Mr Westinghouse and his AC system and required some backward capability to accomodate the existing installed base. (See they had the same issues we deal with right from the start)

Someone with a better understanding of transformers than I will tell you the math involved in the generation/distribution scheme that resulted.


As to what we have now at the building is either:
3 phase 480Y277 or 208Y120 (commercial)
1 phase 240/120 resi (and smaller commercial)

our common recept are 120V 1 phase with a hot & common at each point 240V is limited to higher usage items like cookers and water heaters

there are many exceptions to the above and most will be expanded upon by subsequent posters.

__________________
March 2010: On the road with my RV. California is first primary destination then it is off to Eastern OR, Northern ID and Western MT for drycamping and fly fishing until Labor Day.

te12co2w

At the risk of stirring up the old phase vs leg vs line controversy; on most residential our "distribution boards", what we call loadcenters have 2 lines coming in and one neutral. Each line is 180 degrees out of phase with respect to the other one. Yes, bigger loads across the 2 lines. Our receptacles and our lighting circuits operate with 120v and neutral. Generally speaking that is. I don't understand the 60-50 Hz thing either

cornishsparks

So if you have two hots / phases at 120V each to ground and 240v between them do you fit single pole breakers on the 110v circuits and double pole on the 240 circuits.
How do you get that in one panel board.?

JohnJ0906

This is the only decent picture I can find in my files, and there are no breakers, but you can see the bus, so I will try to explain.



You see the wires coming in the top - 2 insulated, 1 bare. The 2 insulated have 240 volts between them. From each to the bare (the grounded conductor, or "neutral") is 120 volts. If you want 240 volts, you use a double pole breaker, and land the 2 conductors on the breaker - I hope you can see how the busses alternate lines.
If you want 120 v, use a single breaker, land 1 conductor on the breaker, and the other - the white - on the bars to the sides of the main breaker.

__________________
John from Baltimore
"One day at a Time"
All responses based on the '08 NEC
It's not my fault, it's not my problem, I'm not your solution.

JohnJ0906

If (when!) I get the chance, I will take some pictures with breakers and wires connected, you will be able to see better.

__________________
John from Baltimore
"One day at a Time"
All responses based on the '08 NEC
It's not my fault, it's not my problem, I'm not your solution.

cornishsparks

Thanks for the pics will post some uk systems.
On our boards/panels we have seperate neutral and earth/ground bars.
The neutral and earth [ground ] are normally combined when they enter the premises except when they dont supply a ground connection.
We dont ever have a combined neutral ans ground in our panels all our earths are sleeved or insulated.
Looks like your panels are like the old square d QQ three phase boards we used to have over here.
Good quality

JohnJ0906

Actually, this is a main service panel. If we added another panel remote from here, the grounds and neutrals would be separate.

__________________
John from Baltimore
"One day at a Time"
All responses based on the '08 NEC
It's not my fault, it's not my problem, I'm not your solution.

cornishsparks

Oh right i see , wondered how you worked it. is it the electricians job to fit the main panel or the supply companys.

JohnJ0906

The electrician. Directly outside is the meter. Some places it is the electrician's job to install the meter enclosure, some places the POCO (power company) does it. This particular area it is the POCO.

__________________
John from Baltimore
"One day at a Time"
All responses based on the '08 NEC
It's not my fault, it's not my problem, I'm not your solution.

JohnJ0906

This is the only picture I have of a meter that would go along with the 400 amp service I posted.

They are usually not underground...

__________________
John from Baltimore
"One day at a Time"
All responses based on the '08 NEC
It's not my fault, it's not my problem, I'm not your solution.

JohnJ0906

For the previous discussion of this underground install, see this thread : Tight space

__________________
John from Baltimore
"One day at a Time"
All responses based on the '08 NEC
It's not my fault, it's not my problem, I'm not your solution.

BryanMD

John, good for you posting pics but man did you ever pick some awful choices to show as how we do it!

Can that meter even pass inspection being in that hole?

__________________
March 2010: On the road with my RV. California is first primary destination then it is off to Eastern OR, Northern ID and Western MT for drycamping and fly fishing until Labor Day.

jrclen

Common residential electrical service in the USA.
We start with a transformer owned by the power company. The secondary winding supplies us with 240 volts across the winding. There is tap in the center of the winding to give us a neutral point. From each end to the neutral point gives us 120 volts. You are correct about the single pole breakers for 120 volt and 2 pole breakers for 240 volts. At the first disconnect we bond the ground (earth) to the neutral. After that point, those two are kept separate. Our most common modern residential panels contain from 20 to 42 spaces for breakers.

OK. Now how do you do it there?

jrclen

That meter would get a fix or get disconnected notice around here.

JohnJ0906

If you want to comment on that meter, please use that link to the original thread. It wasn't my intention to highjack the thread, it's just the only picture of a meter that I could find.

__________________
John from Baltimore
"One day at a Time"
All responses based on the '08 NEC
It's not my fault, it's not my problem, I'm not your solution.

Trimix-leccy

Uk
Most domestic properties have a 240V single phase 100A supply from the 'POCO'. Regions do not vary [only by name]. All standards are the same [ish ]
Service comes in either L + N + E, or L +N [supply your own earth rod] This is fused at the cutout in the service head...we are not allowed to touch this .
From the cutout it goes to the meter POCO owned, again sealed and untouchable. Then , if you are lucky, it goes to an isolator. After this it goes to the distribution board [wire fuses, HRC or MCB] From here out to each circuit. EVERY circuit has a Live [hot?], neutral and earth connection

N + E are NEVER connected anywhere after the service head. If it is a 2 wire service the N + E are bonded/derived in the service head and sealed.This a CNE or PME service

Larger properties and Industrial units have 3 phase Neutral and earth service. Rated at [usually] 100A, 200A, 315A, 500A the sky is your limit depending on how deep your pockets are. I am presently installing a 1200A per phase 3 phase service to a Server room. Along with all associated Fire supression, sub floor distribution, lighting, fibre optics, Data, telecomms, general power, ACU Supplies, 1000KVA transformer, UPSs etc etc. should keep me busy for a couple of days

As for Inspection...we Inspect and certify our own [subject to being in one of a handful of self-cert schemes] A condition of this is that once a year a bloke turns up, you give him a list of the last years work and he choses a couple of jobs and pulls them to pieces. Anybody on here who has had the NIC man on a bad day will be having heart palpitations at this stage.
The majority of large companies insist on this scheme membership as a condition of employing you. [as do insurance companies]

__________________
TRIMIX...Deep down you know you want it! Trimix-leccy; pulling the envelope---not pushing it

jrclen

Thanks Trimix. Very clear. What do you see for primary voltages for distribution?

PS. I was an avid diver also in my younger days. All the gear is in the basement but I worry about having a heart attach at over 30 meters down. I'm afraid that would be the only and last one.

Trimix-leccy

Sorry, not sure what you term as 'distribution'

externally it is 132Kv to 33Kv to 11Kv [this is usually the local HV ring / radial distribution] local transformers then 11Kv to 415V for distribution to local users. Sometimes there are intermediate transformers at other voltages

Internally there is no voltage change in distribution [usually, unless a very large site]
Factories usally have 415v 3ph distributed locally from a central Distribution board in the region of 800 / 1200A per phase via MCCBs to smaller local boards. Always with seperate neutral and earths. All metal services liable to introduce a potential are bonded to the main earth terminal ie Gas, Water, Oil, Heating duct, structural steel work etc.


.......is that what you meant?.....

__________________
TRIMIX...Deep down you know you want it! Trimix-leccy; pulling the envelope---not pushing it