Can anyone install or repair electrical supply wiring in USA Canada or other countries running a 60 Hz supply service?

Answer for USA, Canada and countries running a 60 Hz supply service.

Electricity is far too dangerous to handle if you have not been trained how to do this work. If you use the wrong size and type of cable for the job and/or put just one wire in the wrong place, you risk being killed by electrocution or you could even start a house fire.

In many places nowadays it is illegal to attempt to do this kind of work unless you are already a licensed electrician or you have applied-for and have received a Homeowner Electrical Permit or an Installation Permit from your local Safety Authority to cover the work to be done at the location.

Enforcement of code requirements varies by jurisdiction in the United States. In many areas, a homeowner, for example, can perform household wiring for a building which the owner occupies; this may even be complete wiring of a home. A few cities - such as New York, for example - have more restrictive rules and require electrical installations to be done by licensed electricians. The work will be inspected by a designated authority at several stages before permission is obtained to energize the wiring from the local utility; the inspector may be an employee of the state or city, or an employee of an electrical supply utility.

How to do this job depends entirely on the Wiring Codes or Regulations for the locality (Town/County/State) and on the exact location of the electrical equipment you wish to be installed.

A GFCI/RCD is needed if the location is subject to water splashes, water spray, dampness or humidity. That applies to any room supplied with running water pipes, like a kitchen, laundry room, bathroom, shower room, etc., or in a workshop, garage or anywhere outside a building in the open air, such as along an outside wall or a pool-side area.

If you get any other answer here, you might attempt to do something you shouldn't be doing, and that may cost someone a shock, a home fire, or even their life.

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As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.