Help - Power/Wiring in public Hall

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amr

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Wannabe Geek

#33222 3-May-2009 22:14

Heya guys

Just looking for some answers regarding electrical wiring etc but more specifically the maximums.

From my understanding the venue has 2 X 15A breakers that are used on the circuits for the power points. Hot water/lights on are their own.

I also have a power reader that tells me the Amps a power socket is using.

Say my computer uses 0.5A; does that mean you could run 60 computers before you had any problems with the power? (15Ax2=30A, 30A/.5A=60pc)

Generally a power outlet has a max of 2400W? What’s the story with double outlets? Are they 2400W max or 2400Wx2? So that would mean around 4-5 computers per outlet assuming they are around 500W max?

What other factors are there? I’m a total 'noob' when it comes to this stuff.

Any assistance or insight would be greatly appreciated.

Thanks in advance

StrangeOne

10 posts

Wannabe Geek

#212701 5-May-2009 22:25

amr: Heya guys

Say my computer uses 0.5A; does that mean you could run 60 computers before you had any problems with the power? (15Ax2=30A, 30A/.5A=60pc)

No. At 0.5amps that's around 115W. You're probably measuring your computer at idle. If your computer is under load it will draw more power.

I'd go more with the 500W max figure. Though you shouldn't be drawing at max power even under full load, it gives leeway for monitors and other peripherals.

500W/225V=2.22 Amps per computer= 6.75 computers per circuit = 6 per circuit x 2 = 12 computers all up.

amr:

Generally a power outlet has a max of 2400W? What’s the story with double outlets? Are they 2400W max or 2400Wx2? So that would mean around 4-5 computers per outlet assuming they are around 500W max?

2400W all up. So, yeah, around 4 per double or two per power point sounds right.

jjnz1

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#212913 6-May-2009 17:48

If its important to get the most juice you can, it might pay to get in a sparky, who may be able to upgrade the 15A breaker to 20A depending on the existing cable.

If your using the computers for basic EDUCATIONAL purposes and not high end GAMING, then each computer will use less and i reckon you could safely work on 250 watts per computer. - so you could get more than 12 computers onto one 15A circuit.

Some circuit breakers are normally rated so that a short rise in power usage (ie 10 -30 minutes of about 10% above rated current) will not trip the circuit.

If your hall has 'safe' wiring, then just try with what you think it will handle, if the fuse blows, disconnect some stuff and try again.

LennonNZ

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#212941 6-May-2009 20:31

Depending on the computer at idle a machine might use 0.5A -> 1A . But turning it on initially maybe 1.5->2A.

From a 15A Fuse I would guess maybe a max of 12-15 machines.. but it really depends alot on what they are going to be used for.. how big they , what they are doing to be doing. Maybe 10 or less if you are running high end gaming machines with 20 fans in them :-)

The only real way is to use a powerboard with a power meter on it and add computers until maybe 75% of max so you have plenty of headroom from when the computers start to do something.

amr

10 posts

Wannabe Geek

#213060 7-May-2009 09:35

Heya guys

Thanks for the replies. Your info and advice is fantastic.

This is for a LAN so its not easy to assume the types of computers that will be there.

My own pc (c2d 2.3ghz, 9800gtx) uses around .4A idle. I have to test it when gaming and see the difference.

I think getting a sparky, despite the cost ><, is the smart choice. Even just to get a clear picture of the situation.

I have been told that a double plug on the wall however counts as 2, so 2400W max each. Is this the case?
2 computers per plug seems a little low.. Ive had a garage LAN with 10 computers off of 1 plug before 0_o

How do other LANS get away with having 30-50 computers in one room? Are newer buildings generally equipped with much better wiring?

Thanks again :)

Nety

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#213074 7-May-2009 10:00

Wow think of how much power is used at xlan 800 gaming PC's plus all the swithches etc...

Edit: This site might help you out.

http://extreme.outervision.com/psucalculatorlite.jsp

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dolsen

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#213107 7-May-2009 10:52

amr: Heya guys

I have been told that a double plug on the wall however counts as 2, so 2400W max each. Is this the case?

Thanks again :)

No, this is not the case (mostly).

Each socket in the double outlet is rated at 10A, so, 2400W @ 240V, however,
You are constrained by the 15A circut breaker, 15A*240V ~ 3600W.

So, you could draw 2400W off 1 socket, and, 1200W of the other one. Drawing 2400W of both sockets should trip the circut breaker (could try with 2x hot water jugs).

That's the theory anyway, in the real world, other things come in to play (gauge wire to sockets, length to sockets, voltage at site, tolerance of circut breaker, type of load (some products draw much more at startup than running, so, you might be able to run the product if it was running, but, be unable to turn it on. Circut breakers normally allow for tempary overload for a small duration to allow for this)).