Unless a property is new, or you have it newly rewired yourself, it is hard to know how old the wiring is and, crucially, if it is safe.

There are tell-tale signs of old electrical work, such as surface-mounted cables, old-fashioned light switches, flexes and ceiling roses, and fuse boxes that use fuse wire, rather than pop-out fuses.

However, fuse boxes are sometimes replaced without the rest of the wiring being updated, and many with pop-out fuses don’t comply with current regulations.

The only way to know for sure is for a qualified electrician to check the electrics. This should be done every 10 years anyway, even if you think everything is fine, and whenever you buy a property, as if you do need to rewire, it can cost thousands of pounds.

Of course, a full rewire isn’t always necessary - your home’s wiring may just need updating, such as adding or moving sockets or wiring in new light fittings.

Smaller jobs like these are less expensive and disruptive than a full rewire, but they may reveal problems with the wiring that you hadn’t anticipated.

If you are doing major building work, such as converting the loft or adding an extension, the electrics in the whole house or flat will usually need to be tested in order to get a completion certificate for the building work. Again, this can throw up unforeseen problems, which can be expensive to put right.

However essential though, changing the electrics is always a dirty and disruptive business. It often involves chasing out (making a hole in) wall and ceiling plaster to create channels, and taking up or chasing out the floors, making it hard to remain living there - or even having furniture there - while the work is being done.

Rewiring takes place in two stages - the first and the second fix.

For the first fix, the cables are laid and the messy work is done to get them in place. The electrician should leave you with a few, temporary sockets that still work, so you can still operate extension leads from them, but the new cables won’t be live which leaves you with very limited electrics.

Before the second fix, the rooms have to be replastered - the plasterer should fill in the chases made by the electrician and then skim the walls and ceilings. After this, the electrician can wire up everything and connect the new fuse box, so you’re back in business.

It’s legal to do some, minor electrical work yourself, but if you don’t know what you’re doing or you just want to play safe, employ a qualified electrician (checking their credentials and references).

The easiest option is to use an electrician who belongs to a government-approved ‘competent person scheme’, such as NICEIC (see www.niceic.com).

These electricians can self-certify that their work complies with building regulations - Part P of building regulations covers electrical work and applies in England and Wales.

If your electrician doesn’t belong to a competent person scheme and the work they’ve done falls under building regulations, you’ll have to pay a building control officer from the local council to check it, or an improved inspector, who does the same job but for a private company.

Alternatively, you can ask an electrician who belongs to a competent person scheme to inspect and test the first electrician’s work, which is often a cheaper option. Plenty of qualified electricians know exactly what they’re doing, but can’t sign off their own work because they haven’t passed additional exams. The key thing is, though, that you get the relevant completion certificate so you can prove that the electrical installation is safe and legal, something often essential when it comes to selling or renting out your home.