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Thread: How much power can a standard power point provide?

  1. #1
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    How much power can a standard power point provide?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Is it ok to attach:

    1) A computer with 22" panel, laser printer and standard 2.1 speakers (averaging about 250W draw)
    2) A Sunbeam EM6910 (? draw)
    3) A small fridge (335kWh/annum draw)
    4) One 8W low power flourescent light
    5) One 20W halogen bulb
    6) One 60W traditional light bulb.
    7) A Sunbeam EM0480 grinder


    .... to a single power outlet?
    :o

  2. #2
    Senior Member flynnaus's Avatar
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    Re: How much power can a standard power point prov

    I believe it is something to do with the total amperage (current) available. Standard household circuits in Aus carry 10 amps.

    You have to work out the total current of all your devices and make sure they dont exceed 10 amps
    The formula is amps = power/voltage.
    e.g. A 2400W device at 240V would draw 10 amps (at full power). A 60W globe would draw 1/4 Amp.

    Your computer + screen would probably draw up to 5 amps depending on the power supply (usually around 400W). Youd also need to know the power drawn the fridge but there would be a label somewhere. but dont forget the compressor isnt running the whole time anyway. The wattage of the Sunbeam should be printed somewhere.
    You need to think about all these devices operating at the same time for there to be a concern. Youll know youve gone to far when the fuse/safety switch goes off.

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    Mal Dimal's Avatar
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    Re: How much power can a standard power point prov

    Unfortunately, its not as simple as that.....

    I dont have a copy of the S.A.A. - 3000 Wiring Rules handy but in order to determine if your sub-circuit is up to the load you wish to place on it, you need to do a Maximum Demand calculation. This looks at the types of loads connected, whether theyre permanently connected, intermittent, etc etc... Accumulated demand doesnt come into the equation (as per your fridge) but its load profile does.

    If you have any doubts, its best to ask a qualified electrician to check things out for you, e.g. you might be better off to split the heavier load devices between two separate sub-circuits rather than have them all hanging off one. And, for all you know, you may have other devices connected to the same sub-circuit and not even realise it thus driving the load beyond the rating of the cable conductor size from time to time; and if you have cables buried under insulation in the ceiling or in the walls, this makes the situation even worse since the cables arent able to cool down via exchange through air flow.

    More to it than one first realises..... ;)

    Mal.

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    Senior Member flynnaus's Avatar
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    Re: How much power can a standard power point prov

    True. The quality of the wiring is certainly a factor and I didnt think about other devices on the same sub-circuit but I thought it might give some general indication. I doubt that ezralimm would be paying for an electrician to come and check this out (unless he has some sparky mates)

    By the sound of it ezralimm, I think you are stretching it a bit with all this on one power point and I would take the fridge or computer off if possible, especially if your EM6910 is on all day.


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    Re: How much power can a standard power point prov

    Theres a lot of ifs and buts in there, like how old the wiring is - Is it solid core 2.5mm2 or stranded 7x0.67 2.5mm2, little subtleties in amongst those previously mentioned by Mal.

    The actual load you have there on the circuit seems fine to me, but you may want to split it over a couple of powerpoints, even if theyre on the same cct. Most household GPOs are only supposed to be max. loaded to 10A, but more often than not, the circuit breaker is rated to 16A or 20A (depending on how its run, or age), and then again if you have an old switchboard with old re-wireable ceramic wedge fuses, then thats another story.

    Some food.

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    Re: How much power can a standard power point prov

    I wouldnt be entirely happy running a PC and a grinder on the same circuit either: some motors can generate "nasties"

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    Re: How much power can a standard power point prov

    Why not get one of those power boards with a 10amp safety cutout. Im guessing they are about $10. Then if it cuts out you know it is too much.

    I dont know much about house wiring, so someone can correct me if that isnt a sensible thing to do.

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    Re: How much power can a standard power point prov

    I thought it was more like, the powerpoints are rated to 10A, but the circuit at 15A. Ive regularly had 2x 2200W elements hooked up to one powerpoint as part of my brewery and that didnt phase it, nothing even got warm or anything (disclaimer: dont try this at home). and thats even more than 15A.

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    Re: How much power can a standard power point prov

    Quote Originally Posted by reubster link=1216720362/0#5 date=1216782356
    I wouldnt be entirely happy running a PC and a grinder on the same circuit either: some motors can generate "nasties"

    Aite guys... Ive not had any problems so far.


    PC + Grinder + EM6910 + two lamps + bar fridge

    PC has been stable so far. Then again, I do have a decent PSU that withstands occasional power blips where lights dim for half a sec.



    Thanks for the feedback :)

  10. #10
    Senior Member flynnaus's Avatar
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    Re: How much power can a standard power point prov

    Might be worth feeling the power board, cable and power point. If there is significant warmth when all devices are operating, some caution might be necesssary. I still recommend having the fridge on a different power point, especially if it contains stuff you need to keep cold


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    Re: How much power can a standard power point prov

    Quote Originally Posted by flynnaus link=1216720362/0#9 date=1216942435
    Might be worth feeling the power board, cable and power point. If there is significant warmth when all devices are operating, some caution might be necesssary.
    So what exactly constitutes significant warmth mate? :-?

    A degree of heat will always be evident from a power board, because by nature its an over-loading of multiple drawing capacitators from the one source (ask any sparky ... they despise power boards).

    My reckoning is to minimise the over-load nightmare by expending a bit of dosh for extra points, & run separately as many appliances as possible - avoid doubling up with power boards & double adaptors.

    I (stupidly) once powered my NS Mac (4000 watt) from a 10amp lead one weekend. It worked, but the male 3 pronged points were blue, & the plastic encasing was starting to bubble & melt. After only 40 minutes.

    And yep, there was a s*** load of significant warmth! :o

  12. #12
    A_M
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    Re: How much power can a standard power point prov

    As a Qualified sparky and having many years working with this stuff... *I would suggest that you "ezralimm" *split *it up asap.

    1: No problems to date: *However *when you arrive home to find the fire brigade out side a burnt out shell - Your place. *Is it then worth it ?

    2: In general the public have become complacent today with respect to power and proper management of its use. *

    Part of the blame here is of course the massive availability of products that require POWER and plug packs etc.. *Supply and demand.

    Only last year *I am aware of 3 separate instances *where house fires were started by power boards ( too many $2 specials available from the cheep shops) . *These were all home of kids in one grade, at one school. *


    Note: *As there are Double and Quad GPSs the house wiring / sub cct *will be *capable of managing more than 10A. * However if you put it in to perspective and DRAW 10A from each GPO outlet... *That is significant....

    Further more the 10A rating is a guide and what the pin contacts etc are rated at. AS3000 and AS3200 AS 3760 go into all of this.

    Thus:


    1: A single power board with a breaker to a single outlet on a GPO. *
    2: Do not piggy back a number of *power boards. *( Exception was for low powered devices - Phone charges and plug packs.) *However today you can get *6 and 8 outlet boards (usually with a over load cct for good reason)

    Can you break these rules and get away with it ... YES *Can I drive at 180k down the high way - yes.

    BUT - it is your choice and thus you have to accept and take any outcomes on the chin.

    I can not afford to rebuild or to loose the lives of my family.. *At the end of teh day it is a small cost to have extra GPOs put in (if required) and to buy good quality power boards and to use them correctly.

    NOTE: In stand by, your system may be OK... However the surge at start up will be much greater than you think. *If teh fridge starts up at the same time as ya PC and the grinder etc etc then the intial current spike will be a killer.

    That is why toasters, Fridges, Dryers and washing machines etc should never be on teh same cct. *

    Enjoy ya coffee but stay safe.

  13. #13
    Senior Member flynnaus's Avatar
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    Re: How much power can a standard power point prov

    Good answer AngerManagement but you just dobbed yourself in?:

    Where do you live? (EDIT: Brisbane - damn!!!)
    You do domestic work?
    CS discount?
    When are you available?
    :)

    Just kidding - unless you need the work

    I had a mate who was a sparky who refused to do any electrical work outside of work hours (except for me once to return a favour and he still wanted to charge me parts + laboour. (He was the short arms - deep pockets type)

  14. #14
    A_M
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    Re: How much power can a standard power point prov

    Quote Originally Posted by flynnaus link=1216720362/0#12 date=1216959754
    Good answer AngerManagement but you just dobbed yourself in?:

    Where do you live? (EDIT: Brisbane - damn!!!)
    You do domestic work?
    CS discount?
    When are you available?
    :)

    Just kidding - unless you need the work

    I had a mate who was a sparky who refused to do any electrical work outside of work hours (except for me once to return a favour and he still wanted to charge me parts + laboour. (He was the short arms - deep pockets type)
    Yep as per my Profile *Nth Side Brisbane.. * Gave up the sparky work years ago ( Big mistake with the wages they are today) but retained a restricted, as needed for my Biomedical work. *Fitter and Turner by trade, but could not run a CNC to save my life today.. Too many changes. Also dropped my MCSE certification, as that got too expensive to maintain.

    However always willing to help out a fellow CS member, be it in IT or Coffee. * However parts are expensive, and while initial assistance may be free... I fully support any barter type agreements for the labour content *;D

    For too long I did too much for free and while some were appreciative, many (including family) just push it to far. * Wife keeps a tally in her head and those that *abuse the relationship are soon identified (I get an ear bashing) and most then are obliged to move on :o

    As I *indicated *before... Enjoy the coffee and doing little mods / repairs, but above all stay safe.

  15. #15
    Senior Member flynnaus's Avatar
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    Re: How much power can a standard power point prov

    Quote Originally Posted by AngerManagement link=1216720362/0#13 date=1216965319
    Gave up the sparky work years ago ( Big mistake with the wages they are today) but retained a restricted, as needed for my Biomedical work. *Fitter and Turner by trade, but could not run a CNC to save my life today.. Too many changes. Also dropped my MCSE certification, as that got too expensive to maintain.
    OK I had to admit having to look up to see CNC so youre already doing better than me (and quite a few others on CS I imagine). So biomedical, F&T, computer and electrical huh - you make or have something to with prosthetics Im guessing..

    You seem fairly safety-conscious. The mate I was talking about told me how Dunlop Volleys were the stock footwear (rubber soul) and he would sometimes work live hanging off balconies.

  16. #16
    A_M
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    Re: How much power can a standard power point prov

    Quote Originally Posted by flynnaus link=1216720362/0#14 date=1216974050
    Quote Originally Posted by AngerManagement link=1216720362/0#13 date=1216965319
    Gave up the sparky work years ago ( Big mistake with the wages they are today) but retained a restricted, as needed for my Biomedical work. *Fitter and Turner by trade, but could not run a CNC to save my life today.. Too many changes. Also dropped my MCSE certification, as that got too expensive to maintain.
    OK I had to admit having to look up to see CNC so youre already doing better than me (and quite a few others on CS I imagine). So biomedical, F&T, computer and electrical huh - you make or have something to with prosthetics Im guessing..

    You seem fairly safety-conscious. The mate I was talking about told me how Dunlop Volleys were the stock footwear (rubber soul) and he would sometimes work live hanging off balconies.
    Off topic.. Should be in another post :-) Scientific , Forensic and Pathology actually; Technical consultant, Contract management, Quality and Procurement: with some training tossed in for good measure.

    From a safety aspect, when at home, I often work in bare feet and use ally ladders... Trust me, there are good reasons. Off site, a different approach.

    For further topic matters, I will be taking some current draw readings to asses the surge current of the EM6910 and EM 0480 over the weekend. Do not have access to a full logger but should be able to get some basic rms readings.

  17. #17
    A_M
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    Re: How much power can a standard power point prov

    Ok Here are my findings for the EM6910.

    Note: As every machine is different and the way it is set-up i.e. Temp settings, steam etc *the values are to be used as a guide only. In addition as the Fluke *Y8101 current clamp and my Fluke 8060B have their own tolerance and specs; surge currents were not able to be measured as I was using the *X 10 range and the response times etc are not suitable to capture high frequency peaks.

    1: EM6910 Rated at 2400W at 240V *= 10A *( Manufacturers specs) *;D

    A: At switch on and as expected, *a quick flick to Over Load (surge) and then *settle to ~2.6A in sync with the relay (clicking noise you can hear)

    B: As the heating blocks warm up less surge events and settles to cycles of *about ~2.1A dropping to about ~1.8A

    Making coffee:

    A: *Unit is stable, warm and ready to go.

    B: *Steam on *(small surge to OL) and then steady *at ~2.2A *

    C: *Still steaming and *hit the coffee button - Bigger surge and then settle to ~4.3A

    I was able to get readings as high as 4.6 but quickly fell to ~4.3A.

    Conclusion: *Manufacturer has allowed a *safety tolerance and would suspect that a number of surges would exceed 10A, *but would be for a very short time. *This is Normal *::)


    All power boards come with a warning that the total load is not to exceed 10A. The standard house hold GPO contacts etc are rated *at 10A

    Thus the EM 6910 *should not be powered from a power board, if other devices are also running from teh same power board *;)

    Not unlike Car insurance, if *the unit is un-roadworthy or has unapproved mod etc; your insurance can be then invalid. *

    As the power boards are clearly marked and the EM6910 is rated at 10A, if you had addition units plugged in, and a fire was the result. *Then some, could easily argue that your house insurance should not cover the event that you have created, as all the information is clearly available. *You choose to ignore and are then responsible *:o

    NOTE: *As I did not do an extensive range of testing covering all possibilities, Steam, Water and Coffee *at the same time with settings to MAX. *I can *only state with conference that my system does not have a continuous draw *that would exceed ~5A but does have surges that exceed 10A (for a very short time).

    EM0480 Grinder.

    Rated at *128 - 150W *Thus at 240V *0.625A * using the main on/off toggle switch.

    A: * Sharp Surges and inital stable draw of 0.310A

    B: *As the grinding continues, settled to 0.235A

    C: *In pulse mode; front pressure switch. *If I pulsed the unit I got more surges and initial values of *0.415A that quickly followed the values measured above.

    Note: *Would can only assume that again the manufacturer has allowed a tolerance and depending on the age of the unit and the hardness of the beans etc that the current draw could be greater than the worse case 0.415A that I got for my system.

    Closing note: *The sooner the law stops impacting on the laws of nature and natural selection... The less I have to fear that the movie "Idiocracy" may be the final reality *:-/







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