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Murphy's Law - Electrics

Most people will be familiar with Murphy's Law*, which is based on the adage 'If anything can go wrong, it will'.

This is especially true within the theatre and, indeed, anytime a live performance is being made. So, here - from experience - is Murphy's Law related to the electrics department.


  1. The only tool vital for a job will be missing.
  2. After the last of 16 mounting screws has been removed from an access cover, it will be discovered that the wrong access cover has been removed.
  3. After an access cover has been secured by 16 hold-down screws, it will be discovered that the lamp has been omitted.
  4. Any wire cut specifically to length will be too short.
  5. The availability of a replacement part is inversely proportional to the need for that component.
  6. An instruction booklet or operating manual will always be where it is supposed to be, until it is needed.
  7. After carefully rewiring a plug, it will be found that the cover has not been fitted beforehand.
  8. Any instrument when dropped will roll into the least accessible corner.
  9. When repairing a damaged lead, it will always be found that the connection that is examined first is fine.
  10. Interchangeable parts won't.


  1. The more innocuous a design change appears, the further its influence will extend.
  2. The probability of a dimension being omitted is directly proportional to its importance.
  3. Dimensions will always be expressed in the least usable term. Velocity, for example, will be expressed in furlongs per fortnight.
  4. All constants are variables.
  5. In any given computation, the figure most obviously correct will be the source of error.
  6. A decimal point will always be misplaced.
  7. The availability of a sound effect is inversely proportional to its significance in the show.
  8. In any given price estimate, cost of equipment will exceed estimate by a factor of three.


  1. Firmness of delivery dates is inversely proportional to the tightness of the schedule.
  2. A critical bolt will be too short, or just too long.
  3. If a rig requires n luminaires, there will be n-1 available.
  4. A dropped tool will land where it can do most damage. (Also known as the Law Of Selective Gravitation.)
  5. A luminaire or extension lead, chosen at random from a group having 99% reliability, will be a member of the 1% group.
  6. All extension leads will always be either four inches too short, or six feet too long.

During The Show

  1. Probability of failure of a fuse or bulb is inversely proportional to ease of replacement.
  2. The only gels that burn out will be the ones that are no longer in stock.
  3. Cue sheets will always be in the wrong order.
  4. Radio mics will always be switched on, until they are actually needed.
  5. Any error that can creep into the timing will. It will be in the way that will cause most havoc.


  1. Murphy's Law was not propounded by Murphy, but by another man of the same name.
  2. Addendum to Murphy's Law: You never run out of things that can go wrong.

See also:

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