Is it true that a 120v 15amp household electrical outlet can only handle 2.4 HP on a vac?

[ShowCar]

I read that somewhere. The math works out if it's true (I think). I ask because I saw a lot of talk about getting a 5hp+ vac. But if you can only get 2.x HP, why worry about it? Just get a 2hp vac. Hoping for thoughts? Is it all just marketing on the HP?

[Becciasm]

I read that somewhere. The math works out if it's true (I think). I ask because I saw a lot of talk about getting a 5hp+ vac. But if you can only get 2.x HP, why worry about it? Just get a 2hp vac. Hoping for thoughts? Is it all just marketing on the HP?

can't say i agree with that math, as i use a 5 hp shop vac off of a standard outlet that also powers a refrigerator and a 'charging' station for my cordless power tool batteries.

[BillE]

My brain is not working too well yet this morning, but one horsepower equals 745.7 watts.

Can't seem to remember the rest of the formula to go from watts to amps. Having a major CRS moment...sorry.

Bill

[BradsDetailing]

Just used a 5hp wet vac yesterday in a power strip, with no issues.

[poweraid]

I run , what is it. ? 8hp master blaster off 15amp with no problems . I can surely tell when I flip each switch on at a time that she blows twice as better ?

[erichaley]

If you're running a refrigerator on that outlet, you're looking at a 20 amp circuit minimum. A quick look at your breaker panel will tell you...

When I moved into my town home, I was told not to put a fridge or freezer in the garage because the circuit breaker (15 amp) would trip.

[Setec Astronomy]

Ay ay ay, this thread is already going like that nitrogen vs. air one. You need a "20 amp circuit minimum" for a refrigerator??

EDIT: I just looked at my 10 cu. ft. that I have in my basement, which is about the size you would put in your garage...6.5 FLA (Full Load Amps).

[jfelbab]

I read that somewhere. The math works out if it's true (I think). I ask because I saw a lot of talk about getting a 5hp+ vac. But if you can only get 2.x HP, why worry about it? Just get a 2hp vac. Hoping for thoughts? Is it all just marketing on the HP?

That is technically correct. Here is the formula.

15Amp x 120 V = 1800 W.

1800 Watts / 746 Watts/HP = 2.4 HP.

The reason many are able to run higher horsepower devices is that those devices are not rated in true horsepower but equivalent or peak horsepower. A 15A circuit can only support at most 1,800 Watts or 2.4 true HP.

Fortunately most devices of this nature also state their true wattage on a label somewhere. Or they simply state that they draw 12.4 amps at 120V. or some such

My 5.5 HP Shopvac label states
Air Flow: 195 (CFM)
Sealed Pressure: 59 (inches)
Electrical Ratings: 120V 60Hz 11.5A
Peak Air Watts: 345

If we look at 11.5A @120 Volts we come up with 1380 Watts or 1.9 true HP.

[jimjc]

If I remember correctly it`s like 2 1/2 hp. from a standard outlet that you have described, I could be off a bit. But is a 5hp. motor a 5hp motor in the first place? I have a real 5hp motor running one of my compressors, now thats a real 5hp motor.

The thing to remember is that these Vacs are "rated HP". in other words the motor genie designers wave a wand and " turn a smaller motor into a larger one to sell all out there on the idea they have a bigger one and not a small one" HEHE
Ah just another example of how they keep everyone dumb on everything they can, sorry for the rant. :doh:

[Setec Astronomy]

The thing to remember is that these Vacs are "rated HP". in other words the motor genie designers wave a wand and " turn a smaller motor into a larger one to sell all out there on the idea they have a bigger one and not a small one" HEHE

It's probably based on the inrush current.

[erichaley]

Ay ay ay, this thread is already going like that nitrogen vs. air one. You need a "20 amp circuit minimum" for a refrigerator??

EDIT: I just looked at my 10 cu. ft. that I have in my basement, which is about the size you would put in your garage...6.5 FLA (Full Load Amps).

Maybe "minimum" was the wrong word here... :)

[FUNX650]

That is technically correct. Here is the formula.

15Amp x 120 V = 1800 W.

1800 Watts / 746 Watts/HP = 2.4 HP.

The reason many are able to run higher horsepower devices is that those devices are not rated in true horsepower
but equivalent or peak horsepower. A 15A circuit can only support at most 1,800 Watts or 2.4 true HP.

Fortunately most devices of this nature also state their true wattage on a label somewhere.
Or they simply state that they draw 12.4 amps at 120V. or some such

My 5.5 HP Shopvac label states
Air Flow: 195 (CFM)
Sealed Pressure: 59 (inches)
Electrical Ratings: 120V 60Hz 11.5A
Peak Air Watts: 345

If we look at 11.5A @120 Volts we come up with 1380 Watts or 1.9 true HP.
I'll never doubt that this is true...

-But, then, by plugging in the numbers for the 8hp MasterBlaster I arrive at:

19 amps @120v = 2280 watts
2280 watts / 746 watts per HP = only 3.0563 HP (true HP)

Let there be no doubt...
I'll always stick with my 20 amp circuit recommendation (120v X 20amp = 2400 watts)...
to safely support the 8HP MasterBlaster (19amp X 120v= 2280 watts)

However...
Will the above 8HP MasterBlaster's "true-HP" calculation become an:
OOOPS!!!-moment on/for Metropolitan's advertising-moguls?
__________________________________________________ __________________________________________________


My brain is not working too well yet this morning, but one horsepower equals 745.7 watts.

Can't seem to remember the rest of the formula to go from watts to amps. Having a major CRS moment...sorry.

Bill
Here's the watts to amps formula Bill:

I = HP X 746 / V

Where:
I = amperage
HP = horsepower
746 = wattage per HP
V = voltage
__________________________________________________ __________________________________________________

To sort of 'reverse-engineer' jfelbab's:
Amps X Voltage = Watts; and: Watts / 746 Watts/HP = True HP...formulas:

Then (per the OP's 2.4 HP example):
I = 2.4 X 746 / 120
I = 1790.4 / 120
I = 14.92 amps.......Appears to be OK.

Using The MasterBlaster's 8 HP "rating":
I = 8 X 746 / 120
I = 5968 / 120
I = 49.73 amps......Appears to be a little high.

Using the above calculated MasterBlaster's true-HP "rating":
I = 3.0563 X 746 / 120
I = 2279.9998 / 120
I = 18.9999 amps....Appears to be OK.
__________________________________________________ __________________________________________________

HMMM: 3HP vs. 8HP...Go figure!!

:)

Bob

[The Pad Man]

If it has a standard house plug it will work. A standard house plug is rated for 15 amps, the outlet and the wire feeding it and the breaker also. If you say plug in a microwave, toaster and coffee pot on the same circuit, it will definitely trip.

[rwright]

I'll never doubt that this is true...

-But, then, by plugging in the numbers for the 8hp MasterBlaster I arrive at:

19 amps @120v = 2280 watts
2280 watts / 746 watts per HP = only 3.0563 HP (true HP)



Bob

Bob, is it possible MasterBlaster uses a step up transformer with their products?

[FUNX650]

Bob, is it possible MasterBlaster uses a step up transformer with their products?
It's possible. I've never torn one down to see 'the windings', though.

But whenever using a step-up transformer to increase the voltage...
you don't get something for nothing:

-As the voltage goes up, the current goes down...by the same proportion.
The following "power equation" shows that the overall power remains the same.

P = (V) x (I)

Where:
P = Power;
V = Voltage
I = Current

In the real world...Power output is always less than the power input.
-This is because the changing (alternating) magnetic field of an
AC-transformer creates eddy-currents which, in turn, heat the core.
-This heat is then lost to the environment. It is often considered/called: "wasted energy".

-An additional core-transformer-winding, (such as found in step-up transformers),
would only seem to sorely exacerbate the amount of "wasted energy", IMO.

Then again...
Perhaps this: "hot-wasted-energy"...is where the MasterBlaster's "heated-air" comes from.


:)

Bob