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Formulas for Ohm's Law
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Ohm's lawNobody can say exactly what electricity is.
We can describe what it does... it is the force that moves electrons across the surface of a conductor.
For example a copper wire is a conductor, and electricity can be used to move electrons down the wire.
When the electrons arrive at a light bulb, electricity pushes the electrons across a narrow filament inside the bulb.
The filament is also a type of wire, except smaller than regular electric wire.
When electrons are pushed across the small wire, the wire becomes hot, and begins to glow.
The glowing wire becomes the light from the light bulb.
How do we know what size wire and how much electricity is needed to cause the light bulb to give off light without also causing the larger wire to get hot?
That's where ohm's laws is used.
While we can't say exactly what electricity is, we can predict what it will do using ohm's law.
Ohm's laws are a series of formulas that help electricians and engineers design functional electrical and electronic systems. The basic formulas are shown in the ohms law wheel.
Ohms laws have been used in common practice for many decades.
Over time, reports arise about the peculiar things electricity can do... such as jump across wires and cause shorts and fires.
The practical experience over time, plus application of ohms laws has given rise to the National Electric Code.
The code is a guideline that standardizes wire and breaker sizes, and establishes best practices.
The practical application of ohm's law and the code lets electricians safely wire a house or a business.
energy is applied to any atom, the electrons in orbit around the
nucleus will jump to a higher state of energy.
Jumping to a higher state means the orbit of the electron is farther away from the nucleus.
When electrons are farther away from the nucleus, they become less bonded to the nucleus.
The nucleus has harder time keeping the electron in orbit.
With conductive materials, such as copper or silver, the electrons can become free from the nucleus with fairly low amount of energy applied to the conductor.
When electricity is applied to a copper or silver wire, the electrons begin jumping from one atom to the next atom.
They leave the orbit around one nucleus and jump to the orbit of the next nucleus. This dislodges the electron in that orbit And the cascade of atoms begins to flow down the wire.
Apply the correct amount of electricity to the correct size copper wire, and the flow of electrons becomes a useful tool for rotating motor, powering lights, and running a computer. Too much electricity, and things burn out. Too little electricity, and some circuits stop working while others can overheat.
Conductive materials have another interesting property
A power line for example. If lightning hits near a power line it will energize the wire.
This causes additional electrons to flow down the wire and is generally called a surge event.
The additional flow of electrons from a surge can knock out electric and electronic devices. Surge suppressors and arrestors help solve problem.
As a result, we know wires will absorb energy from nearby electrical source.
The same principle is used in a transformer. Transformers are basically two coils of wire located next to each other, each coil wrapped around a metal core and neither touching the other, with no shared wires in common.
Transformers are used to convert one voltage to another voltage. And according to Ohm's law, when voltage is changed, the amperage changes in inverse proportion.
There is an inverse relationship between volts and amps. The formula in ohms law is volts x amps = watts.
Transformers utilize this formula. Transformers convert high-volage low-amperage electricity into lower-voltage higher-ampeage electricity for end user.
So transformers will convert 7200 volt distribution electricity into 240 volt household electricity.
High-voltage wires arrive in your town and neighborhood from the power plant. These are transmission and distribution wires, and carry low amperage to reduce heat loss.
Low amperage is important for long distance transmission of electricity because high amperage causes heat loss on the wire, and reduces transmission distance.
To achieve low amperage, high voltage is necessary. Using Ohm's law, the correct voltage and amperage and wire diameter and distance of transmission can be calculated.
Resource: What is 3-phase electricity/ Power plant to end user
Once at your home, the high-voltage low-amperage wires enter a transformer. There is usually a transformer for each home or for each two homes. Inside the transformer are two coils of wire wrapped around an iron core, cooled by oil. The high voltage wires connect to one coil.
The wires going to your house connect to the other coil.
Resource: See inside main breaker box
When the high voltage coil is energized it produces an electric field that causes electrons to flow in both coils...
Only the high voltage coil receives electricity from the generator, but the flow of electrons through the high voltage coil will cause electrons to flow in the other coil.
Remeber the coils are not connected. they just sit next to each other. It is the same principle when a lightning strike causes a surge of electrons on the wire.
The reverse is also true.
In a electrical outage the high voltage line has no electricity. Local homeowner might connect a generator to thier breaker box to supply power to the refrigerator.
Electricity from the homeowner generator will travel to the transformer causing a flow of electrons that will energize the other coil that sends electricity into the 7200 volt line.
Of course the homeowner generator is not powerful enough to re-energize the grid. It may only cause a neighbor's light bulbs to burn slightly, but this electricity is dangerous for anybody trying to repair the outage. As a result a transfer switch is required when connecting a generator to your breaker box. Ot the homeowner could turn off main breaker to stop electricty from reaching transformer.
The high voltage wires are connected to a coil of wire that is wrapped around an iron core
And the wires going to your house are connected to a coil of wire wrapped around a iron core
Neither coil is connected to the other coil
Both coils are next to each other inside the transformer.
One coil will have more wraps around the iron core than the other coil. That is how the voltage is changed.
There are formulas that determine how many wraps each coil should have depending on the voltage and amperage ratio that is needed
Both coils have electrons that move when one of the two coils is energized
As a result the high-voltage coil will energize the lower voltage coil.
All transformers work the same.
For example phone charger is transformer.
When you plug in his cell phone transformer, 120 volts from the outlet is converted to a smaller voltage that is used to charge the battery in the cell phone
= Amperes X Ohms
Amperes = Volts/Ohms
Ohms = Volts/Amperes
Watts = Volts X Amperes
Watts = (Volts X Volts) / Ohms
Watts = Amperes X Amperes X Ohms
Ohms = Watts / (Amperes X Amperes)
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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.
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