Power wall socket question

Forums › Home Workshop DIY › Power wall socket question

Lizard1977

2045 posts

Uber Geek

ID Verified

#142533 16-Mar-2014 10:03

We are moving things around our house, and that means bringing my large desktop PC and my wife's similarly oversized PC into the same room. We've got a long desk where both PCs will reside side by side. The problem is that the room has very few power sockets on the wall. On the wall we have the PCs against, there is only a single wall socket. On the opposite wall there is a double socket and two single sockets. However, the desk won't work on that wall, and the other two walls of the room are already occupied.

I'm wondering whether the power draw on a single wall socket will be too much. Is there a way to work out the power draw/capacity of the socket? The equipment that we will be using on that socket includes 1xPC (650W PSU), 1xPC (760W PSU), 2 x LED monitors, 1 x powered speakers (25W RMS), 1 x stereo (70W+70W RMS), and one inkjet printer.

If the single socket can't handle the power draw, then we have the short term option of running an extension cord from the opposite wall around the room but that's not ideal. It would be better to have an electrician replace the single socket with a double socket. How expensive would that likely be?

1 | 2 | 3

2136 posts

Uber Geek

ID Verified

Trusted

Lifetime subscriber

#1006588 16-Mar-2014 10:12

The standard NZ domestic power outlet is 10A, although you also need to check to see what size fuse/circuit breaker is supplying this.

Saying this, 2 computers and their assocated accessories should run just fine off 1 outlet

Tradepub

Free professional, reference and technical white papers (affiliate link).

sbiddle

30853 posts

Uber Geek

Retired Mod

Trusted

Biddle Corp

Lifetime subscriber

#1006594 16-Mar-2014 10:25

A standard power socket is rated at 10A and the fuse or circuit breaker will typically be 10A, but could be 15A. Basic ohms law will let you work out the load.

Your PC's won't use anywhere near the PSU rating unless they're under full load which is highly unlikely. Unless you have the PC's fully kitted out with HDD's and high end video cards and actual draw is probably around 1/4 of this tops.

Bung

6361 posts

Uber Geek

Subscriber

#1006613 16-Mar-2014 10:58

The only thing typically 10A is the cheap breaker built into plug strips. The fuse or breaker rating is determined by the .cable and its surroundings. Short term current higher than nominal probably wouldn't trip either. In an office if you ever manage to trip the breaker it's surprising sometimes how many other computers are affected.

Lizard1977

2045 posts

Uber Geek

ID Verified

#1006617 16-Mar-2014 11:05

Thanks. I figured the socket would be 10A, but I wasn't sure whether that 10A would be shared across all the sockets in the room. Our fuse board is on the old-ish side (that's a whole other story) and it looks like the fuse/circuit breaker is either 16A or 6A (i'm guessing the former).

The PCs wouldn't be at full load all the time, but I figured the PSU wattage would indicate maximum usage. I reckon the total maximum wattage would be no higher than 1700W, which at 240V gives about 7A and 34ohms. So I think the single socket approach should be fine...

Sideface

9236 posts

Uber Geek

Trusted

Lifetime subscriber

#1006641 16-Mar-2014 11:46

The item that draws the most power is the printer - although inkjets don't draw as much as laser printers.

Sideface

gregmcc

2136 posts

Uber Geek

ID Verified

Trusted

Lifetime subscriber

#1006648 16-Mar-2014 11:55

Bung: The only thing typically 10A is the cheap breaker built into plug strips. The fuse or breaker rating is determined by the .cable and its surroundings. Short term current higher than nominal probably wouldn't trip either. In an office if you ever manage to trip the breaker it's surprising sometimes how many other computers are affected.

I think you need to re-read what you said here, the fuse or breaker rating IS NOT determined by the cable and it's surrroundings, you need to go and take a look at a circuit breaker and read the number on it, a 10A circuit breaker has a rating of 10 amps.

If everything is done right then the size and length of cable that the circuit breaker suppplies will be able to handle the rated maximum capacity of the fuse or circuit breaker, been a power circuit at least the rating of the outlet, in this case 10A

ArcticSilver

729 posts

Ultimate Geek

#1006650 16-Mar-2014 11:57

Lizard1977: Thanks. I figured the socket would be 10A, but I wasn't sure whether that 10A would be shared across all the sockets in the room. Our fuse board is on the old-ish side (that's a whole other story) and it looks like the fuse/circuit breaker is either 16A or 6A (i'm guessing the former).

The PCs wouldn't be at full load all the time, but I figured the PSU wattage would indicate maximum usage. I reckon the total maximum wattage would be no higher than 1700W, which at 240V gives about 7A and 34ohms. So I think the single socket approach should be fine...

You'll be fine, easily!

You wont reach your power supply's maximum. No need to worry there, I would expect around 350watts per PC under load.

I run a computer LAN (www.got-lan.co.nz) and do the power for it. I load 6 computers onto 1 10a circuit. 2 is a very light load.

The monitors, speakers, stereo and inkjet will most likely not equate to a 3rd PC worth of power. I would estimate with everything going, on full load you'd be lucky to use 5amps (or 1150 watts out of 2300).

Lizard1977

2045 posts

Uber Geek

ID Verified

#1006654 16-Mar-2014 12:01

Thanks everyone, puts my mind at ease. I think we might invest in a decent multiboard to handle 7 plugs, to try and keep things nice and tidy...

Sideface

9236 posts

Uber Geek

Trusted

Lifetime subscriber

#1006673 16-Mar-2014 12:29

IF you know how to do simple mains wiring, consider replacing your single socket with a 4-way power point (cost about $25)

I have 4 of these in my PC room - one on each wall.

Sideface

sir1963

3221 posts

Uber Geek

Subscriber

#1006682 16-Mar-2014 12:48

Lizard1977: We are moving things around our house, and that means bringing my large desktop PC and my wife's similarly oversized PC into the same room. We've got a long desk where both PCs will reside side by side. The problem is that the room has very few power sockets on the wall. On the wall we have the PCs against, there is only a single wall socket. On the opposite wall there is a double socket and two single sockets. However, the desk won't work on that wall, and the other two walls of the room are already occupied.

I'm wondering whether the power draw on a single wall socket will be too much. Is there a way to work out the power draw/capacity of the socket? The equipment that we will be using on that socket includes 1xPC (650W PSU), 1xPC (760W PSU), 2 x LED monitors, 1 x powered speakers (25W RMS), 1 x stereo (70W+70W RMS), and one inkjet printer.

If the single socket can't handle the power draw, then we have the short term option of running an extension cord from the opposite wall around the room but that's not ideal. It would be better to have an electrician replace the single socket with a double socket. How expensive would that likely be?

Ok lets add up the power draw.
PC 650 W (this is a maximum, normal use will be lower)
PC 760 W (this is a maximum, normal use will be lower)
2 LED monitors , lets say 50w each = 100w
Speakers 25W
Stereo 140w (Maximum, normal would probably be 20w)
Printer allow 100W (will be less )

So total maximum = 1775w maximum (= 7.7A @ 230v)

A Standard power outlet is 10A, with a nominal voltage of 230V that gives a maximum wattage 2300W
so you are well within this limit.

HOWEVER, here is where you may have problems.
In most situations multiple power outlets are wired in series, typically on a 15A-15A circuit breaker depending on wire size (1.5mm/2.5mm), so for that circuit you can draw about 3500W to 4600W. SO... depending on what else is running on the same circuit you can still have problems.
For example if you were to run a 2300 fan heater in another room on a circuit with a 15A breaker you would end up close 18A, this will eventually cause the breaker to trip (probably after a few hours, I won't go into close/course protection).

You commonly see this in kitchens where people run multiple high wattage appliances like a frypan and kettle at the same time.

Lizard1977

2045 posts

Uber Geek

ID Verified

#1006686 16-Mar-2014 12:52

Thanks for that breakdown Sir1963. I guess that "series" issue is what I was thinking of when I wondered about the total draw of the entire room. Worth keeping in mind, but in practice the sockets on the other walls won't be used. There isn't any other tech in the room, so it should be okay.

Lizard1977

2045 posts

Uber Geek

ID Verified

#1006689 16-Mar-2014 12:53

Nice idea Sideface but I wouldn't trust my wiring skills that far. One day we will get the whole house re-wired, and when that day comes we'll definitely be improving the number and accessibility of power sockets, not to mention wiring for data as well.

Bung

6361 posts

Uber Geek

Subscriber

#1006702 16-Mar-2014 13:40

gregmcc:
Bung: The only thing typically 10A is the cheap breaker built into plug strips. The fuse or breaker rating is determined by the .cable and its surroundings. Short term current higher than nominal probably wouldn't trip either. In an office if you ever manage to trip the breaker it's surprising sometimes how many other computers are affected.

I think you need to re-read what you said here, the fuse or breaker rating IS NOT determined by the cable and it's surrroundings, you need to go and take a look at a circuit breaker and read the number on it, a 10A circuit breaker has a rating of 10 amps.

Step back a bit. How does the rating of the protection get chosen? Do you see 1 socket and put in a 10 amp breaker or do you look at the appropriate breaker for the size of cable and how surrounded in insulation it will be?

]

gzt

16921 posts

Uber Geek

Lifetime subscriber

#1006732 16-Mar-2014 14:59

Is there a way to work out the power draw/capacity of the socket? The equipment that we will be using on that socket includes 1xPC (650W PSU), 1xPC (760W PSU), 2 x LED monitors, 1 x powered speakers (25W RMS), 1 x stereo (70W+70W RMS)

Rule of thumb maximum allowed power draw for one socket at wall outlet is 2400W. (10A@240V)

But, if you are getting within shouting distance of 2400W for long periods of time or unattended you do not want to be using a multiplug type thing (due to increased fire risk).

sbiddle: Your PC's won't use anywhere near the PSU rating unless they're under full load which is highly unlikely.

Agree. If peace of mind is required you can get a rough indication of total loading using $25 power meter and some typical activities running on the machines.

Lizard1977: It would be better to have an electrician replace the single socket with a double socket. How expensive would that likely be?

My guess is $70-$140 to get the upgrade depending on area etc.

Signature goes here.

sir1963

3221 posts

Uber Geek

Subscriber

#1006738 16-Mar-2014 15:16

Lizard1977: Thanks for that breakdown Sir1963. I guess that "series" issue is what I was thinking of when I wondered about the total draw of the entire room. Worth keeping in mind, but in practice the sockets on the other walls won't be used. There isn't any other tech in the room, so it should be okay.

The power outlets in the room may well be on the same breaker as the power outlets in another room.

It is not uncommon with breakers for 4-6 sockets to be on the same breaker.

1 | 2 | 3