"CJ" wrote ...

The standard household outlet is 120V,

but it surprises me that I have a gas powered (powered by a weedwacker

motor) snowblower that can move 300 lbs/min.

yet I see electric models that can move 700.

interestingly no electric weed-wacker seems to outpower my 1 hp gas

unit. (uses the same motor and has a cool snow blower attachment).

this raises some questions.

1: if they can make a more powerful snow blower, why not a more

powerfull electric weed-waker?

Maybe there isn't a need for a more powerful weed wacker?

It takes a lot less energy to cut weeds than to throw snow.

It seems that they can just keep putting on bigger motors and making

electrical

devices such as snow blowers more powerfull.

Until you run into the power limitations of the circuit that you are on.

2: What are the limits to the power in watts that can be derived from

a standard outlet?

Most household circuits (United States) are 15 ampere at 120volts.

Watts = Volts times amperes = 1800 watts

Ever wonder why there are so many hair dryers and other portable appliances

are rated at 1500 watts?

It lets you plug them into a circuit that has a light bulb on it without

blowing the breaker.

Kitchens will have a couple 20 amp circuits because they tend to have large

power devices on them.

You could install a 20 amp circuit for your portable tool, but you will have

a hard time finding an extension cord that is rated to carry 20 amps. Get

beyond 20 amps and the wire starts to get really heavy and well beyond what

you would want for a portable tool.

The other alternative is to increase the voltage of the circuit. This is

what is done for the typical very high loads in houses (electric stove,

central air conditioning, and large shop tools.

My stove is on a 50 amp 240 volt circuit (12,000 watts)

My air conditioner is on a 30 amp 240 volts circuit (97,200 watts)

You really would not want to lug an extension cord made to carry the power

for those circuits.

R: R = E / I

I = W / E

W = (I^2)*R

E R I Watts HP

120 1 120 14,400 19.3

Do you realize the size of the wire you would need to provide 120 amperes?

Look at the wire running into your house from the power company.

Many houses only have 100 amp services.

That means that Just by adding resistance we can get infinitely more

HP?

Only if you supply the additional voltage to keep the current constant.

This is the reason that large household items are powered by 240 volts, you

can supply more power without increasing the current to numbers where the

wiring is huge.

So for our One HP snowblower,

one HP=(750Watts) if we have 120 V, then I=6.25 (do to W = (I^2)*R)

This means we only have .052 Ohms on our one HP snowblower. Doesn't

.052 seem a little low to derive such power?

You are thinking backwards on that one, and your math is off.

750=(6.25^2)*19.2

You do not derive more power from more resistance on a circuit. If you keep

the voltage constant, lower resistance will cause more power dissipation

(FYI: on an AC circuit, it is technically the impedance instead of

resistance and it is related to the resistance and inductance of the

device).

P=E*I and E=I*R thus P=(E^2)/R