How to monitor power usage on a wall power outlet? - Page 1
Forum section: electronics / beginners

author: sam1000islands
author_rank: Newbie
timestamp: May 26, 2021, 07:47:06 pm
content: On my home desk I have 2 monitors, 2 laptops, backlit LED, CalDigit active cable hub, 2 Raspberry-Pi's, speakers and external HDD.They are on most of the times and I am worries I might be overloading my wall power outlet!So I have 2 questions:1- How can I know the maximum possible current draw on a single wall electric outlet before something goes wrong?2- How can I monitor power usage on the power outlet?

author: ledtester
author_rank: Super Contributor
timestamp: May 26, 2021, 07:55:18 pm
content: If you are in Canada I doubt you are overloading your wall outlet. In the US a standard residential outlet supports 15A.To monitor your power usage, you can get a device like a "Kill-a-watt" or search for a "electricity usage meter/monitor" or "power monitor".

author: mariush
author_rank: Super Contributor
timestamp: May 26, 2021, 08:04:23 pm
content: Quote from: sam1000islands on May 26, 2021, 07:47:06 pma typical lcd monitor = 40-60 wattsa laptop = 30-70w typically (see power adapter, it will say maximum power the adapter can produce, the laptop will consume less than that)raspberry pi = 10w maybespeakers ... 10-50w maybe depending on amplifier type, volume etcexternal hdd .. less than 10wYour sockets are rated for >10A so you have at least 1000 watts available. Your power consumption is way less than what a mains socket can supply.

author: Jwillis
author_rank: Super Contributor
timestamp: May 27, 2021, 05:42:16 pm
content: Get yourself one of these. You can probably pick on up at any building supply/ hardware store .Plug Power MeterThese will show you outlet voltage , current draw , and power consumption .

author: atmfjstc
author_rank: Regular Contributor
timestamp: May 27, 2021, 06:58:30 pm
content: I wouldn't bother with measurement. None of the devices there, even in multiples, will even remotely exert a power outlet. As a ballpark, monitors and similar sized objects will rarely draw more than 100W, while handheld sized objects like the Pi will draw around 15W worst case. You're not gonna hit the outlet's limit unless you try really really hard.You only need to start paying attention once you plug in either:- Large electrical appliances that deal with heating or moving parts (washing machine, space heaters, aircon, microwave)- Beefy desktop PCs (e.g. with multiple GPUs or multiple PCs)

author: wizard69
author_rank: Super Contributor
timestamp: May 27, 2021, 07:19:46 pm
content: Quote from: sam1000islands on May 26, 2021, 07:47:06 pmAdd up the volt amp ratings on the power adapters. This will likely give yo a max current draw number, some devices may never hit that max (day a desktop with unpopulated slots and a low end video card) but it can give you a worse case number.QuoteThere are a number of ways to go about this. You could buy something like a "Kill-a-watt" monitor for example. Fluke and others sell break out "cords" or adapters that allow the use of a clamp on ammeter. If you have your own ammeter you can make up your own cord to allow the use of a clamp on meter.QuoteA "kill-a-watt" or similar device is pretty meuch designed for this. An example:https://www.newegg.com/p3-international-p4400-1-outlets/p/N82E16882715001?item=N82E16882715001&source=region&nm_mc=knc-googleadwords-pc&cm_mmc=knc-googleadwords-pc-_-pla-_-surge+protectors-_-N82E16882715001&gclid=EAIaIQobChMI3dzS1cfq8AIV4R6tBh01kwCjEAQYAiABEgJrJ_D_BwE&gclsrc=aw.dsI do believe there are competing units.Of course this is a consumer approach there are all sorts of commercial ways to monitor power usage on branch circuits.Beyond all of that, unless you breaker is tripping I kinda doubt that you have a problem with an over load of the circuit. However an overload of the break out strip can be a problem because there are some with dodgy construction out there.In North America, in areas using NEMA standard components you usually try to keep the current draw on a branch circuit below 80% of the protective device for the circuit in question. This is because overload devices in this jurisdiction are designed to trip eventually at the indicated rating. Thus a 15 amp fuse will eventually blow if you try to pull 15 amps from such a circuit continuously. In other areas the stamped rating on the fuse may indicate its continuous current rating.

author: AtomicRob
author_rank: Contributor
timestamp: May 27, 2021, 09:37:50 pm
content: If the original question was motivated by the fact that a breaker is tripping or fuse blowing, then you'd have to look at what other receptacles are on the same circuit. Older homes especially may have an electrical system that doesn't meet current codes. In this case you might have a lot more appliances on the same circuit than you realize. For example my home was built in the 1950's and prior to rewiring the whole thing we had knob and tube wiring, ungrounded receptacles, and like 6 circuits for the whole house. In that case your 300 watts of office equipment might be on the same circuit with the hairdryer, the TV, the stereo, hopefully not the kitchen, you get the idea. A kill-a-watt only tells you what's directly plugged into that outlet. To figure out what else is on the same circuit you could just turn off one circuit breaker at a time and see which receptacles go dead by plugging in a lamp.

author: wizard69
author_rank: Super Contributor
timestamp: May 28, 2021, 04:54:44 am
content: This sounds a lot like my house, built in the 1950's also. Apparently the original breaker box has 4 breakers upon which somebody spliced in another 4 breaker box. That stuff is gone now but yeah most of the house was on a couple of circuits.This is a good point for people in really old homes because even after upgrades some stuff gets left on a circuit it shouldn't be.As for the original poster this is a good example of why somebody should post the "why" behind the question.Quote from: AtomicRob on May 27, 2021, 09:37:50 pm

author: Jwillis
author_rank: Super Contributor
timestamp: May 28, 2021, 07:45:07 am
content: One thing that tends to get neglected and forgotten is circuit breakers can wear out and get weak when tripped repeatably . If you having issues with breakers tripping with light loads , it might be worth you while to replace those .Most modern breakers have life time as well and should be replace every 15 to 20 years . Some more expensive ones do have a life expectancy of up to 30 to 40 years. Arc fault (AFCI) and ground fault (GFCI) should be replaced every 10 - 15 years . The sensors tend to wear out faster than the breaker themselves .Receptacles should be replaced anytime the contacts seem loose or if their is any visible browning (burning) of the receptacle . And in some cases it may not be visibly apparent . This type of browning is typical of receptacles than have electric heaters plugged in often . Contacts inside become burned and more resistive . This sort of thing can cause problems with other appliances and lead a person to think theirs either something wrong with the appliance or a problem at the breaker panel . If the plug seems overly rough when inserting then it may be time to replace the receptacle . If a 2 prong plug drops on an angle then it's time to replace the receptacle.

author: Terry Bites
author_rank: Super Contributor
timestamp: May 29, 2021, 11:52:14 am
content: https://www.homedepot.com/p/Gardner-Bender-Energy-Usage-Power-Meter-PM3000/300905368