Sunday, March 4, 2007


At the most LANs getting enough electricity is a challenge and at our LAN it's no different. Larger LAN may use a diesel generator to have enough juice if the facility can't supply it. Even if your location says it has the power you need you may still have to rent power converting equipment to use it. At our lan there is "appears" to be enough electricity in and around the building but I can know for sure with out seeing the circuit breaker panel.

In most circumstances you would go look at the circuit breaker panel to find and mark which outlets are on each circuit but the room where we have held our last 2 LAN Parties, the electrical panel is in a locked closet that maintenance seams to be unwilling to unlock. So we have relied on blind luck not to blow the circuit breakers.

In the room we are using there are several 20 amp outlets characterized by the use of NEMA 5-20R outlets (See the picture, one prong has a T shape) but what I don't know is if each one of these outlets is on it's own circuit or shares with another outlet 5 feet away. A 20 amp circuit can theoretically carry 2400 watts of electricty (calculated by using watts = amps*volts) but most will trip when they reach around 80% load (about 16 amps or 1920 watts)

I'm tempted just to carry down 3 1000 watt microwaves down to the room and plug 2 into one outlet and 1 one in another and have them boil water till I trip a circuit breaker and and after a few minutes if the breaker doesn't trip I will know that they are on separate circuits.

At the event it is optimal to provide 3 to 4 amps for each computer. Even though some of the desktops have a 500 watt power supply that won't come close to using it. Most computers don't use as much electricity as they think. My very high end Desktop rig only draws 300 watts (or about 3 amps) so planning for 4amps is more than enough. Usually you shouldn't have more than 5 or 6 desktops on a 20 amp circuit.

Another thing you have to take into account is the number of amps that a power strip and extension cords can carry. 20 amp power cords and power strips are expensive so we split them over 2 separate power strips and extension cords carrying 10 amps each. The power strips we use can handle 15 amps but the extension cords are different. The 25ft cords can handle about 14 amps but our 50ft cords can only handle 12 amps and if you use even longer cords, the number of amps drops even more.

At our event, since we have so many laptop users I take this in to account when planning the power setup so we can minimize the number of extension cords we have to buy. An average laptop uses around 100 watts or about one amp of electricity. We seat 2 laptops and 2 desktops to a power strip thus maximizing the number of computer we can power.

I'll add some more pictures later. I have all summer to bug the maintenance department to mark the electrical circuits.

No comments: