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See inside main breaker box

Electricity from power pole to breaker box

Electricity arrives from the pole
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Neutral wire is same size at Hot wire so each can carry same current
Ground wire connects to Neutral wire
Ground wire is smaller diameter than Neutral and is for household safety

Power poles carry high-volt, low-amp electricity

High-volt low-amp lets power company transmit electricity long-distance without heat loss caused by high amperage.

Before entering house, electricity is converted to lower volts and higher amps at transformer. Different transformers are used for different voltages. Residential transformers receive power from 1 high voltage line. The transformer reduces voltage to 120Volts and splits the voltage into two 'out-of-phase' 120Volt Hot wires that enter home. The two out of phase hot wires offer 240Volt potential used to power water heaters, air conditioner etc. While the single-phase 120volts is used for outlets and lights.

Homes with underground utilities have meter and meter box, but wires arrive in conduit pipe from underground. Transformers are inside ground-level boxes at edge of property.

Note: 3 wires enter home <> 2 hot wires and 1 neutral wire <> the neutral also connects to ground wire at pole. Ground wire is smaller gauge than neutral wire. Neutral wire is same gauge as hot wires so it can carry voltage equal to the hot.
Where power comes from: What is 3 phase
Read about transformers
Read more
Read details about 3-phase
Fuse on power pole
Full image

Fuse cutout and lightning arrestor located on power pole

High voltage must pass through a fuse before connecting to transformer.
Fuse protects transformer from surge caused by lightning or overload
Fuses trip when heat exceeds fuse rating.
Electric company resets fuse using long fiberglass pole

Image shows high voltage line terminating on last pole at end of street
Tripped fuse can also signal that transformer is out of service
Tripped fuse
Tripped fuse
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120-240Volt transformer
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See another image of household single phase and split phase
Read about source of electric power
Inside household distribution transformer
General illustration showing two coils inside residential split-phase transformer
High voltage line supplies 7200Volts to one coil. Voltages vary.
When current flows through 7200 volt coil, it causes current to flow through second coil
Both coils are separate, and not connected by wires.
Current applied to first coil will cause current to flow through second coil even when the coils do not touch each other or have any shared wires.
Each coil has different number of wraps of wire.
Different Voltage and amperage is achieved by number of wraps on each coil, and by wire diameter etc.
Read: Transformer theory .pdf
Read: Distribution transformers .pdf
Read more about electricity generation: What is 3-phase electricity
distribution transformer
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Residential drop wire Example service drop wire
Triplex means 3 wires twisted together to form 1 cable. Electrician can buy triplex at home center or electric supply.
Quadraplex is 4 wires twisted together to form 1 cable
Many different types of bundled cables are available to electrician in larger and smaller diameter

2 Hot wires and 1 neutral wire leave transformer and drop to weatherhead located on side of home or local pole
Example triplex has 1 non-insulated wire for neutral, and 2 insulated wires to carry Hot1 and Hot2 from transformer to meter box
Normally 1 wire is solid black and other is solid black with yellow stripe
Triple drop wire
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Neutral is same gauge as Hot wires, so Neutral can be used to carry voltage equal to incoming  Hot without overheating
Ground wires are smaller and cannot carry full voltage without overheating. Ground wire is for safety.
Why you need ground wire
Electricity at meter pole
Ground wire is smaller gauge than neutral

How to get electric service

Call local electric company: Ask for specifications and permit for connecting electric service.
Electric company may required licensed electrician before approving installation, or in rural areas they may allow homeowner to install the meter box and weatherhead.
Specifications must be followed:
Install meter box and weatherhead on side of any stationary building. Unskirted Mobile homes and RV and temporary buildings and dilapidated structures usually require separate pole for meter and weatherhead.
RVs will plug into outlet that is attached to conduit below the meter box. Power cut off required at connection point.
Breaker box can be installed on pole. Or conduit can be run underground into any structure where it terminates in a breaker box. Breaker box must have a main breaker.

Height of weatherhead, height of meter box, size of conduit, size of wire, size and type of pole, location of ground rod, ownership of property, billing address, setback distances, proximity of power pole and transformer, trees, other buildings, etc must be considered.
There must be 8' ground rod installed at the pole with proper grounding by local code.

Meter box, conduit, wire, ground rod and weatherhead available at local store. Install meter box and conduit and ground rod.
Run wire from meter to weatherhead, and leave specified amount of wire hanging out of weatherhead. Power company will inspect meter and wires, and then attach drop-wire from pole, install meter into meter box, then re-engage fuse at power pole to energize the service.
Electric company will not connect power unless conduit terminates into a shut off box or is continuous to a main breaker shut off inside breaker box.
Example service installation manual
Meter box and weatherhead
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2 hot wires 

1 neutral wire 

enter weatherhead

Weatherhead sold local home center and electric supply
When home or business has underground service, there is no weatherhead.
Purpose of weatherhead is to keep water out of mast, meter box etc.
Water must be kept out of mast or underground conduit, or short can occur.
Water can also cause rusted box and deterioration of electrical connections.
Underground residential electric service

Underground residential electric service

Transformer is underground instead of local pole
Meter and meter box located on side of house, same as above-ground service
Meter and meter box
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Install Meter Box (shown on side of building)

Three wires enter meter box.
Same 3 wires arrive for underground or above ground service connections
Connect wires as shown. Use large allan wrench to tighten lugs against copper wire.

There are 2 hot wires and 1 neutral wire. The 2 hot wires come from the transformer. The neutral is connected to ground wire at telephone pole.

The meter 'stabs' into meter box using 4 prongs, similar to extension cord plugging into a wall socket.

The meter completes the circuit and lets electricity flow to house.

The 3 wires exit meter box and go to Main Breaker Box
Meter and meter box
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Meter and meter box

Image shows meter and meter box:
Buy meter box at local electric supply. Power company installs meter when service is connected.
You can buy used and reconditioned meters and install around house to track electric usage of each appliance.
How to install your own electric meter

Pulling a meter requires a stout pull downward and then upward <> usually you pull downward on the top of meter and then push up, going up & down to loosen and remove meter > removing meter will turn off electricity to whole house including breaker box <> however meter box will still contain live electricity <> stand on dry boards when pulling meter <> turn off all circuit breakers in main breaker box before pulling or re-installing meter so there is no arc of electricity just as meter prongs makes contact with lugs

Inside Main Breaker Box
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2 Hot wires / 1 Neutral wire/  enter main breaker box

Ordinary household wiring is called 'single-phase' or 'split phase.'
120 volt is generally called single-phase and 240 volt is split-phase.
The available voltage is determined by how the electric company sets up the transformer.

2 Hot wires and 1 neutral wire arrive from meter box.

Blue color added to 1 hot wire for illustration <> in real breaker box, the 2 hot wires are black

The 2 hot wires connect to the Main Breaker <> a lug is tightened very tight to hold wire in place. Neutral is connect to neutral busbar.

Each hot wire connects to different busbar through the main breaker > here the busbars are named A and B > the 'blue' hot wire provides power to blue busbar <> remember, blue color added for illustration only

Hot busbars are 120 Volts each > they never touch each other > they are suspended away from the main box by insulators

240 Volt potential exists between busbar A and busbar B
On some apartment and condo services, 208 Volt potential exists between busbar A and busbar B, and 120 Volt between each hot busbar and either busbar A or B

See basic 120V and 240V water heater circuits

Difference between 120Volt and 240Volt

Inside main breaker box are Three busbars.
One busbar is Neutral busbar.
Two busbars are Hot busbars.
Each Hot busbar is 'out of phase' with the other.

Bare ground wires are bonded to Neutral busbar as redundant safety.

All residential circuits require Two wires to complete circuit.
**120Volt circuit requires 1 Neutral wire and 1 Hot wire.
Hot wire can come from either Hot busbar.
By Code, these wires are Black-Hot and White-Neutral.
If either wire is interrupted, the circuit turns OFF. By code the Black Hot wire is switched ON-and-OFF.

**240Volt circuit also requires 2 wires to complete circuit.
In the case of 240V, the circuit requires 2 Hot wires.
One Hot wire from each 'out of phase' busbar is required to complete 240Volt circuit.
These wires can be Black and White or Black and Red, and with heavier gauge wires, like 6 gauge and 4 gauge, the wires are Black and Black.
If either wire in 240V circuit is interrupted, the circuit turns OFF.
See 30 amp switch turning off water heater
Question: Are both sides of the breaker 30 amp or one each one of them 15 amp ?

Answer: I had that discussion with a guy and did some research on electrician forums... which was a battle over sine waves and ultimately inconclusive.

Then I remembered reading an industry .pdf that said you can make a 240 breaker by combining 2 single-pole breakers, but that code requires you to install a 'common bar' between the breaker so if one trips, then the other breaker also trips...
Then I remembered the oscillating (sine wave) nature of electricity, where AC power reverses the direction of electrons 60 times per second... over and over and over... and how the voltage rises and falls as electrons come to a stop, reverse direction and accelerate the opposite direction... yet the average voltage is always above zero, and the oscillations happen so fast that it is not a noticeable factor for electricity as we humans use it.
Then I remembered that each leg of a 240 volt circuit is out-of-phase with the other leg.... which means the sine wave for one leg is mirror of the other leg... and the load receives more sustained power ...which is why we use 240 volt instead of 120 volts... because it is more efficient. This means each leg is delivering power to the load, and thus is independent of the other leg. Of course that is true because the electrons travel back and forth on the wire... and so one leg is pushing electrons when the other leg is pulling electrons ... this increasing total power, and this can be represented by the formula E = IR, or power (watts) = volts x amp. The formula shows if you have 30 amp, and change the voltage from 120 to 240, then the power (watts) goes up, or the amps (heat loss on wire) decreases.
... the final conclusion... the answer is that both breakers are 30 amp... because both are pushing and pulling electrons down the wire, like pedaling a bicycle with two legs instead of one.
... so yes... the answer is that both breakers are 30 amp.
Figure volts amps watts
Formulas for ohm's law
What is electricity
How a generator works
Main breaker warning

Main breaker warning

Screws on main breaker are HOT at all times
Even when main breaker is OFF, both screws are HOT
Only if meter is PULLED are these screws safe to touch
main breaker box
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120Volt and 240Volt breakers

Image shows 120Volt line and 240volt line.
Both circuits have ground wire.
Each 120 and 240 require two wires to complete circuit.
120V requires 1 hot and 1 neutral
240V requires 2 hots
Ground wires are for safety.
Read more about 240 volt

Some 240Volt lines have additional neutral wire. However, neutral not necessary to complete 240Volt circuit.
Some 240Volt lines have white and black instead of red and black

Most service boxes today have separate Neutral and Ground busbars, but these busbars are bonded together electrically, and are the same.
Illustration on left shows both Neutrals and Grounds on same side of box. In actual box, the Neutral is on right side and ground on left. Illustration shows separated neutral and ground so it is easier to illustrate wires leaving breakers.
Color code and wire sizes
Basic 120 volt and 240 volt water heater circuits
How to wire 240 volt outlets
How to wire 3-phase outlets and timers
How to convert 240Volt  water heater to 120volts

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Install meter on subpanel

How to install subpanel
New and used electric meters
How to install electric meter on water heater or subpanel
How to wire tankless electric water heater

Color code for wire and wire sizes
How to install electric meter on water heater
Install circuit breaker
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How to replace circuit breaker
Breakers are held in place at both ends <> one end locks into a cleat -or- snaps onto a bar <> other end of breaker rotates to busbar and then 'stabs' onto the busbar

Push firmly to make sure breaker is stabbed all the way down

When replacing a breaker, check busbar for damage or burning from previous breaker <> busbars are frequently damaged by aging breakers that arc and burn <> arcing will damage busbar so new breaker will no longer work in the same slot. Read steps 32-37:

When lights flicker, check breaker immediately before sparking causes damage in breaker box. Check breaker and listen for fizzing or crackling sound. Check if the breaker screw is tight against wire. Flickering lights are usually a loose wire at a plug, but it pays to check breaker first to avoid busbar damage.

Always put cover back on breaker box to prevent sparks from leaving breaker panel.
Read how to replace circuit breaker
circuit breaker resources

Circuit breaker resources

Water heater is tripping breaker
How to replace circuit breaker
How to wire gfci
Can AC breaker be used for DC breaker
How to reset circuit breaker
Not enough space for circuit breakers/ use tandem
Circuit breakers
How to install subpanel
Why you need ground wire
See inside breaker box
How to wire safety switch
How to wire whole house surge protector
Figure volts amps and watts
Figure correct wire and breaker
Types of surge protection
Larger image

Transformers sitting at electric yard

Each transformer is mult-tap
Multi-tap means the transfomer can be configured for different voltages and applications

3-phase electric
Household electric service
Why you need ground
Pulling elecric wire/ photos

For safety, always put cover over Breaker box <> circuit breakers can overheat from aged breakers or loose wires and cause sparks that ignite a fire 
Electricity is a wave that oscillates.
In the US the wave oscillates at 60 cycles per second. This is called 60 Hz.which appears on appliance labels. Each TV, refrigerator, computer, microwave, etc will have a label that shows Hz or hertz.
Countries such as Australia and India use 50 Hz.
Appliances made for 60 Hz will not work with 50 Hz electricity, and vice versa.
Some timers made by Intermatic and Tork are rated 50-60 Hz and will work globally.
How electric power arrives at each home

In household electricity, both Hot busbars are identical except out of phase with each other.
With 120 volts a single wave oscillates up and down.
Using 240Volts doubles the wave, and since each wave is out of phase with the other, it is like adding an extra cylinder to the engine, and gives added power.
Phasing and voltage is determined by the transformer.

What is 3-phase

3 phase service
3 phase service back of store
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Three phase electricity is more efficient than single-phase
Many businesses and schools use 3 phase electricity.
Electricity is generated at the plant by spinning 3 coils through a magnetic field.
Each coil is separated by 120 degrees.
Each coil produces a wave or pulse of electricity, and since each coil is slightly behind the other during rotation, the result is a 3-phase wave. This type of electricity is AC or alternating current.
Power is sent out on 3 separate wires, one wire from each of the 3 generator coils. Each wire is Hot.
Transmission lines are high voltage and low amperage to reduce heat loss. This allows long-distance transmission. Power from the generator is re-transmitted in several directions at local transformer stations. Eventually, there is a limit to distance electricity can be transmitted.
The field of super-conductivity works to solve problems of transmission loss.

Generally, if a business has 3-phase service, then power is pulled from each of the 3 Hot wires and routed through transformers that determine exact voltage of the service. There are a range of different 3-phase voltages, each determined by the transformer. Most 3-phase buildings also have transformer that convert power to 120 volt single-phase available for ordinary outlets.
How to install 3-phase timer     Read about Delta and Wye     What is 3-phase

Unlike 3-phase, Residential power does not require all 3 Hot wires.
For residential neighborhood, only 1 high voltage Hot wire enters the neighborhood. The single hot wire arrives at each home at a transformer where voltage is reduced and amperage increased. The transformer coil splits the single hot wire so that power entering home has both 120 volt single phase and 240 volt split-phase available as shown in illustrations above.

So each neighborhood is powered by 1 of the 3 Hot wires coming from power plant. Generally, when one area draws power from 1 of the 3 Hot wires, then next area will draw power from 2nd Hot wire. Then the following area draws power from 3rd Hot. This keeps power draw balanced across all 3 Hot wires.
Electricity leaves power plant What is 3-phase electric: power plant to end user

Power pole


Transformers can convert electricity many different ways.
Transformer manuals
Transforming electricity is limited only by mathematics governing the natural world.
For example using a transformer, high voltage and low amperage can be converted to lower voltage and higher amperage used inside each home. There is inverse relationship between volts and amps shown in following formula: Volts x amps = watts.
See electrical formulas

 High voltage 3-phase from the power plant can be converted into many different 3-phase voltages depending on which transformer is used. Resources:
Read about Delta and Wye
The reverse is also possible: Using a transformer, single phase residential power can be converted into certain types of 3-phase.
Since solar generated power is DC (direct current) instead of AC (alternating current) a transformer called an inverter will convert DC solar power into more useful AC power. Different inverter voltages are available by wiring the transformer differently.
Small transformers are used inside each home to convert 120V single phase electricity into low-voltage AC or DC electricity used to recharge cell phones or computer battery or power the 12 volt AC doorbell or 24 volt AC HVAC systems or low voltage outdoor lights. Transformer
Symbol for transformer


DC (direct current) is power from a battery. This type electricity can be stored and used later.
AC electricity cannot be stored without using inverters to store power in DC (direct current) battery. And then it must be inverted back from DC to AC, and each conversion causes power loss due to heat.
Edison, the inverter of the light bulb, originally promoted DC current, and his first large-scale model was to light a city block with DC power using his light bulbs. But it was quickly apparent that DC current could not be transmitted long distance, so AC power is standard service worldwide today.
The problem with AC power is that is cannot be stored, so power generation must anticipate demand, and have enough generators operating to meet demand.
Solar and wind generated electric power has disadvantage since generation occurs at specific times, but not always when electricity is demanded. With wind power, the location of the generator is not often close to where people live, meaning that long-distance transmission loss cuts into overall efficiency.
Three phase motors require connecting all three Hot wires
Similar to 240volt that requires two hot wires
Different 3-phase motors require different voltages.

Peak electric

Off Peak

Peak electric prices result because electricity cannot be stored
Once the grid is electrified, any unused capacity is wasted. Power plants want to produce just enough to meet the demand so additional fuel is not consumed at the power plant.
Generally, coal power plants are slower to come on-line. Natural gas power plants can be turned on-and-off more rapidly. Power companies have to anticipate demand so that power is available at peak demand times.
The capacity issue, among other problems, is why power companies have 'peak' electric prices.
Read about off-peak water heater options

Additional links
Basic household wiring
Basic water heater circuit

Figure volts amps watts for electric water heater
Test elements
Replace elements
How to wire tankless electric
How to change water heater temperature using timer
Change water heater from 240Volt to 120Volt
Replace thermostats
How to wire thermostats
How to wire water heater for off peak operation

How to twist wire
How to wire Cooper 277 pilot light switch
How to wire combo switch-outlet
How to replace 3-speed fan switch

How to wire dimmer
How to wire 3-way dimmer
How to wire occupancy switch
How to wire motion detector
How to wire TM811 and TM8111 switches
How to wire wall timers
How to wire box timers
How to wire off-delay timer
Wire off-delay timer
How to wire pin timers

How to wire and troubleshoot photo eyes
Reverse photoeye so it turns on in day
24 Volt photoeye
24 volt programmable timer

How to wire switches
How to add switch
How to add 3-way switch

Timer for 3-way switch
Timer for 4-way switch

How to add outlet 
How to wire 3-way switches
How to wire 4-way switches

Troubleshoot Malibu outdoor lights
Select and install wire connectors
Select wire size

Electrical formulas
Electricians forum

Electrical pages

How to wire arc fault breaker
How to wire GFCI
How to wire GFCI combo

Basic water heater circuit
How to wire water heater for 120Volt
Install old work box

How to drop wire from attic
Wire connector

How to wire 240volt outlets
How to install 3-phase timer
How to wire 3-phase outlets
How to wire 3-phase surge protector
What is 3-phase

How to wire whole house surge protector
How to wire under-counter water heater

See inside main breaker box
Replace breaker
Install subpanel

How to solder wires
Whole house surge protector
3-phase surge protection
Circuit breakers

Difference between 120 volt and 240 Volt
Difference between 50Hz and 60Hz
How to install electric meter on water heater
How to wire water heater thermostat
How to wire water heater with switches and timers

6x6x4 Enclosures
Intermatic timer enclosures

Read how to convert AC water heater to DC/ high voltage
Convert AC water heater to DC/ low voltage

How to wire DC solar water heater
DC relays for solar water heater
How to add another thermostat to water heater

How many Kwh to heat water
Chart for figuring heating time for electric heater

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