Do you hire a professional to fix your plumbing and do electrical work?

I used to be able to do minor plumbing repairs, and many years ago, when re-building my daughter's bedroom, I re-wired the entire room. Physical problems keep me from doing either. I hire professionals.

Plumbing is easy.  I usually have relatives come help me with electrical, but only because this house is an electricians nightmare.  

 

 Yes and yes.
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I do little easy electrical stuff such as replacing light fixtures, switches, and outlets.   

Plumbing.....all of my disasters have been DIY plumbing repairs.  I have two great trustworthy plumbers; both work out of their homes and they bring one of the kids for helpers.  They are all related. 

I can carry out basic plumbing and simple electrical work to a point, but anything to do with the gas-fired central-heating / hot-water boiler has to be by a "Gas Safe" accredited fitter.

Similarly there are stringent regulations in the UK about electrical installations. These don't ban amateur installers per se, but the work has to be inspected and passed as safe, professionally, before use.

I don't have to, I just give myself about a 30 foot head start when installing the pipes then turn on the water and keep installing the pipe fast enough to stay ahead of the water until the job is completed.

Wiring for electrical is a little bit more tricky.