power the room

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electricity warning

introduction

Electricity makes computers go. I asked an electrician to provide a power network in my tiny data center to feed the LIC (Larg's Internet Cluster).

The LIC uses at most 6 amps. That kind of usage will create an electricity bill of hundreds of pounds a year.

what it is

Get an electrician to do the work. Don't mess around with electricity.

extend the power supply to the shed

I wanted a straightforward domestic single phase electricity supply to my shed. I had no weird equipment such as a three phase pump, boiler or light.

  1. I walked to the local electrical shop.
  2. I bought 25 metres of 30 amp armoured cable (£75).
  3. I collapsed under the weight and phoned a friend with a car.
  4. I dug a trench in the garden between my house fusebox and my shed.
  5. I plonked the cable in.
  6. I paid an electrician to spend a day wiring up the ends, and adding everything else (£450).

add electrical things

LIC topography: electrical things
consumer unit AC power cables extension leads

I paid the electrician for electrical extras. He connected the house end of the power cable to the fusebox and did a fair bit of work at the shed end. I got all this stuff installed.

  • a new consumer unit (AKA fuse box AKA breaker box).
  • four wall-mounted double sockets with switches. My domestic AC power plugs and sockets are defined by a British Standard catchily named BS 1363. Each socket can handle up to 13 amps, way more than I need.
  • two four foot flourescent light strips
  • a light switch
  • wiring for the lights
  • a ring circuit for the sockets

a PDU (Power Distribution Unit)

An extension lead has a domestic AC power plug on one end and a 4 way distribution board on the other. I use an extension lead to go from a wall socket to a rack shelf, where computers are plugged into it.

The extension leads are in effect my PDUs (Power Distribution Units). A PDU is a clever device containing mystical electrical totems like circuit breakers and relays. A PDU controls the feeding of electrical equipment. What this means is that my extension leads are not PDUs, they are PDBs (Power Distribution Boards) ie. a long strip with containing power sockets and nothing else. I am going to ignore this distinction by looking the other way and singing loudly to myself.

backup power

I need two things.

  • a UPS (Uninterruptible Power Supply). If the grid power disappears then I can run the computers from batteries for ten minutes. This gives me time to fire up...
  • a generator. A back-up fossil-fuel generator that won't deafen the neighbours and will produce enough power to supply the LIC would cost £500.

I ran out of cash and could not buy either. Bugger. If we have a power cut then the LIC instantly dies in a messy fashion.

off-grid power

What I would really like is to grow my own electricity. Micro-power appeals to my tree-hugging soul.

Every government created an electrical distribution system many decades ago. This system is called a grid and these days most people in the world are within reach of one. Using the local electrical distribution system is called "being on-grid" by nerds. If you live by an unreliable grid, are keen to produce your own power or live on the moon, you can run your LIC "off-grid". Backup power is off-grid power.

You can build a renewable power station to power your LIC. You need a few things to build a wind-electric hybrid-power system.

  • a fat wallet ($10,000USD should do it).
  • a wind turbine
  • a rectifier/charge controller
  • a photovoltaic array
  • a DC (Direct Current) source center
  • an inverter/charger
  • a battery bank
  • an AC (Alternating Current) distribution grid
  • a technician who can maintain all of these components

what it isn't

The power supply network is, unfortunately, not redundant. One fuse blows and several computers unceremoniously crash. The solution to this is to use a couple of small UPSs (Uninterruptible Power Supplies).