Is it true that a 120v 15amp household electrical outlet can only handle 2.4 HP on a vac?
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Becciasm
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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.
BradsDetailing
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Just used a 5hp wet vac yesterday in a power strip, with no issues.
erichaley
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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.
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
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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).
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
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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.
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:
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
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It's probably based on the inrush current.
erichaley
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FUNX650
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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?
____________________________________________________________________________________________________
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
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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.
Bob, is it possible MasterBlaster uses a step up transformer with their products?
FUNX650
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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
Becciasm
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And let's not forget that nameplate horsepower =/ always equal performance.
When selecting pumps and fans for my projects, they are listed in 'nominal' hp, not exact HP. I may only need a pump with 3.1 hp to move the fluid - but i have to use a nominal 5 hp motor (if using standard 3 phase electric motor sizes).
So, Is it truly 2x4 HP of output, or two nameplate 4 hp motors?
And bob, it's very possible that the waste heat off of the motors is the first stage in heating the air through the blower, prior to a heating coil..
And to the posts regarding "if a refrigerator is plugged in it must be 20 amp" - i didn't plug a fridge into that outlet until after I moved in a year and some change ago. It's on an gfci circuit that feeds both the upstairs bathrooms as well - this circuit only trips if someone upstairs runs a hairdryer, not if the fridge, battery chargers, cell phone charger and GG 6" are running at the same time from the same duplex.
When selecting pumps and fans for my projects, they are listed in 'nominal' hp, not exact HP. I may only need a pump with 3.1 hp to move the fluid - but i have to use a nominal 5 hp motor (if using standard 3 phase electric motor sizes).
So, Is it truly 2x4 HP of output, or two nameplate 4 hp motors?
And bob, it's very possible that the waste heat off of the motors is the first stage in heating the air through the blower, prior to a heating coil..
And to the posts regarding "if a refrigerator is plugged in it must be 20 amp" - i didn't plug a fridge into that outlet until after I moved in a year and some change ago. It's on an gfci circuit that feeds both the upstairs bathrooms as well - this circuit only trips if someone upstairs runs a hairdryer, not if the fridge, battery chargers, cell phone charger and GG 6" are running at the same time from the same duplex.
The HP rating is deceptive, it is the "rated" or "peak" HP of the motor and not necessary the "running" HP from using 120v household current.
Can it get generate the "rated" or "peak" HP? Sure it can with the right amount of electrical current, but it will last longer running on 120 volts.
Companies do this for marketing reasons, seen a 6HP Craftsman air compressor lately? You will commonly see 6HP air compressor advertised, but you will not see it advertised as 4476 watts or 37.3 amps. It is a 6HP rated motor that will pull less than 15amps/ 1800watts from the wall outlet.
Bottom line is that wattage and amps are the more important number as it pertains to household devices on 120v circuits.
Can it get generate the "rated" or "peak" HP? Sure it can with the right amount of electrical current, but it will last longer running on 120 volts.
Companies do this for marketing reasons, seen a 6HP Craftsman air compressor lately? You will commonly see 6HP air compressor advertised, but you will not see it advertised as 4476 watts or 37.3 amps. It is a 6HP rated motor that will pull less than 15amps/ 1800watts from the wall outlet.
Bottom line is that wattage and amps are the more important number as it pertains to household devices on 120v circuits.
poweraid
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I may have brought this up once before ? I'm no electrician and this may be irrelevant . even though mb is 19amp and recommended to run off a 20amp circuit , 19 is less than 20 of course . but is it not true , a 20 amp circuit or appliance the outlet/plug is a 3 prong but with one of the blades to be an inverted T , which any standard 3 prong would still be able to access the outlet . this was just something I ask my local menards elec dept dude about a 20amp outlet and that's what he showed me .
FUNX650
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From this thread (with my: in-red-bolding): http://www.autogeekonline.net/forum...n-metro-master-blaster-run-15-amp-outlet.html
Homes built prior to the early 1960’s were most commonly wired with a two-wire system, absent of the modern third wire: An equipment ground wire.
Old styles (legacy):
Modern styles:
You can compare your outlets to these...
You may be able to "run" an 18 (19) amp appliance on a 15amp service for awhile...But at what risk!!! Just saying........
------------------------------------------------------------------------------------
EDIT: Here's what the 20 amp GFCI looks like:
WR= weather resistant
Really hope this helps some.
Bob
Setec Astronomy
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There is no heater in any of the Metro blowers, they are just running the air over the motor, the same way your vacuum cleaner keeps the motor cool. Put your hand in front of your vacuum exhaust some time and see if it feels warm.