Testing Electrical Consumption

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Old 05-31-17, 10:36 AM
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Testing Electrical Consumption

Hi Iím putting together a home music/video studio and want to make sure that I am not creating any fire hazards with all of my devices. I purchased a P3 Killawatt ( https://www.amazon.com/P3-Internatio...ords=killawatt ) to test the amps drawn by all of my devices and plan to compare this with the amp rating of the outlets in the room where the studio is.

Can you please help answer a few basic questions?


1. Iím a bit uncertain because it seems like there might be discrepancy between the amps Kilowatt is showing and the expected amps of devices. Example: The kilowatt is showing that my iPhone charger (when charging iPhone) is only between .03 and .09 amps. However, Iíve seen many forums where people say that an iPhone charger will draw approximately 1 amp. I want to make sure that there Kilowatt isnít underestimating the total amps being used by the iPhone, as well as other devices too. I called up the company that makes the Killawatt and they told me that it was accurate and there is no way that I could be using it incorrectly.

So I just want to make sure here: should I completely trust that the Kilowatt is giving me accurate readings and assume that the forums that I read had incorrect information? Or do you think that the low amp reading of the iPhone charger doesnít make senseÖ and maybe I should test it with another kilowatt? or take some other actions?


2. I have heard that its likely that my house (in the USA) is rated to supply 15 amps to the outlets in my room. Iíve also heard that its possible that some outlets in the room could be on separate lines/breakers (not sure what the right terminology is) or they could be all on the same line/breaker, and/or they could be on the same line/breaker as other rooms in the house. I think that I need to verify how many amps the room can handle and what outlets are on what line/breaker.

What is the easiest way to find this information out? Can I do this (safely) if I have almost no electrical experience?


3. If I ever did accidentally go over the amp limit, what would happen? Iíve heard that modern houses (my house was built 20 years ago) have systems to cut off electrical surges before they make fires- is this true? Or is this something that I should be concerned about?


4. The Kilowatt also gives me a reading that all my outlets have about 123-124 V . Some of my devices and surge protectors say that they are rated to 120 V. The person from the company said that this should be no problem at all (and I have run the devices/surge protectors for several months without any issues). But I just want to make sure- Is this potential a electrical hazard to have a few more Volts than the devices and surge protectors say they are made for?



Thanks, Dan
 
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Old 05-31-17, 10:59 AM
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The kilowatt is showing that my iPhone charger (when charging iPhone) is only between .03 and .09 amps. However, I’ve seen many forums where people say that an iPhone charger will draw approximately 1 amp
The output of cell phone chargers is about 1A at 5v. That's about 5w (v * A = w). At the input voltage of 120V, you still have the same wattage, but the amperage is 0.04A. (5w / 120v = 0.04A)
So your measurements seem about correct. (You could connect a LOT of iPhone chargers to a 15A wall socket).

I have heard that its likely that my house (in the USA) is rated to supply 15 amps to the outlets in my room.
Yes, most circuits in your house are either 15A or 20A circuits. Each circuit breaker in your main panel, connects to a number of receptacles and/or lights. The total draw needs to be under that 15 or 20A circuit breaker. If it goes above that, the circuit breaker will trip. This protects the wiring from overheating if say you connect a toaster oven, microwave, and fridge all to one circuit. Without the circuit breaker, you could end up pulling 30A from a wire in your wall that's can only support 15 or 20A, which is where the safety issue comes in. That's why circuit breakers (or fuses) are used.

In an already built house, it takes some time to figure out which circuit breaker controls what outlets. It's a trial and error process of connecting a radio or lamp to a receptacle, then turning off each breaker in your panel to see which one controls what. It's a good exercise though, because you probably don't want to be plugging any high-power amplifiers into the same circuit as a basement freezer for example. Though to be honest, the worst case scenario is that the circuit breaker trips.

The Kilowatt also gives me a reading that all my outlets have about 123-124 V
Residential power is typically 120v +/- 5%. I believe power companies consider this approximately 110v - 125v. Everything in your house is designed to work within these ranges, and probably a bit higher and lower too. So what you're seeing is quite standard.
 
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Old 05-31-17, 12:06 PM
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Welcome to the forums but PLEASE watch your spelling. The device you are using for measurement is called a Kill-A-Watt meter. It displays instantaneous volts, amps, volt-amperes and watts, the last two are designations of instantaneous power. It will also display cumulative power consumption in kilowatt-hours which is what your billing is based upon.

A kilowatt is a measurement of instantaneous power equal to using 1,000 watts. Using that power continuously for three hours would result in 3 kilowatt-hours.

The term volt-amperes is used with devices that have a significant deviation from the "volts times amperes equals watts" equation. Such devices include most electronic equipment.
 
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Old 05-31-17, 01:25 PM
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To answer your main question, no you aren't going to burn your house down. The breakers will trip. Running a dedicated 20 amp multi wire circuit to your studio should be more than enough. A multiwire circuit will provide two 120 volt/20 amp circuits. If any of your equipment has a full load amp rating of more than ~12 amps best to run a separate dedicated circuit. No need to use a Kill-A-Watt meter, just look at the amp rating om the label.

A multi wire circuit consists of two hots and a shared neutral from either two handle tied single pole 20 amp breakers on opposite legs or a 20 amp two pole breaker.
 
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