Adapter label and electricity consumption

Question

My surveilance cam label states 5==1A. I am not an electrician, but is it right to say that based on tha label, to compute for Power (watts) consumed by the device:

1A x 120 volts = 120 watts

For electricity consumption:

120 watts x 24 hours = 2,880 watt-hrs per day
2,880 watt-hrs per day / 1000 = 2.88 kwh per day
2.88 kwh per day x 31 days = 89.28 kwh per month
89.28 kwh per month x $.10 per kwh = $8.928 per month

Does that mean that I am spending $8.92 per month for a small camera?

Thanks

First of all I don't understand what 5==1A means and how you concluded 120V from there. Second, it is the maximum rating. — Eugene Sh., Jun 29 '18 at 19:28
No, but you probably spend 8$ a year, and xbox costs 14$ just to have it in off mode — Voltage Spike, Jun 30 '18 at 00:37

score 6 · Answer 1 · answered Jun 29 '18 at 21:54

6

I think you are confusing the symbol for dc current (from electrical-symbols.com):

with a double equals sign. Your camera must be supplied with 5V dc at a maximum current of 1A, so it consumes a maximum of 5W. Your monthly cost is pocket change.

answered Jun 29 '18 at 21:54

Elliot Alderson

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But don't forget that the power supply has its own efficiency, which is lowee than 100%. Still, this shouldn't affect things too much. – AndrejaKo Jun 30 '18 at 07:56

Ale..chenski · Answer 2 · 2018-06-30T16:00:22.140

If your device (or adapter) states "5V=1A", then the device likely consumes 5 W of power, no more. These devices usually are supplied with AC-DC wall adapters. These adapters are NOT linear voltage dividers, they convert input power into output power, almost like an old magnetic-based transformer, just do it a bit differently. And they do this transformation with about 80% efficiency. Therefore if your load (webcam) uses 5 W, the AC-DC adapter will use 5/0.8 = 6.25 W at input. If the "primary AC-side" is 120 V, the whole setup will consume about 50-55 mA of current (6.25W/120V), not 1A as you suspect. Therefore you will be paying about 1/20 of your calculated $9/month, or just 45c per month.

score 2 · Answer 3 · answered Jun 29 '18 at 19:30

Extremely unlikely. Is it possible that it actually says "5V 1A" or similar? That would mean that the cam requires a supply of 5V that can supply 1A (but probably the cam uses nothing like that on average). in other words - it would be a spec for what the supply should be capable of, rather than of the actual usage (which is often not stated).

120W would be a crazy amount of power for a web cam. If you really want to know, you can buy fairly inexpensive ($20 or so) power meters that will measure actual power for you.

Adapter label and electricity consumption

3 Answers3