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2011
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See inside Main breaker box


















































Electricity arrives from the pole
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Power poles carry high-volt, low-amp electricity.

This 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.

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.

Notice 3 wires enter home <> 2 hot wires and 1 neutral wire <> the neutral is a ground that connects to ground wire at pole <> the two hot wires come from the high voltage lines

Meter and meter box
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Three wires drop down from weather head and enter meter box.

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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Image shows meter and meter box:

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 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

See basic 120V and 240V water heater circuits
What is 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 connects 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


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


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


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