Fires caused by electrical faults are on the rise, with Fire and Emergency warning against homeowners attempting to do electrical work themselves.

In the three years to the end of 2019 there was a 22 percent increase in electrical fires and a high number of complaints about work done by people with no electrical training.

Olivia Ogilvie and her partner wondered what was going on when the lights and power sockets in the front part of their rental kept cutting out.

They were alarmed to discover the safety switches in their fuse box had not flicked off as they were supposed to when there was a fault, and after two more outages, called their landlord.

She said the electrician he sent around was shocked to discover a burned out fuse box that was close to catching on fire.

"He said there were some other strange things, indicating that maybe there were other things which had been done incorrectly or too quickly."

A close call for the tenants and for the landlord, who had only bought the home a year ago, expecting the nearly new house would be electrically sound.

Fire and Emergency's Pete Gallagher said it wasn't possible to say how many of the 641 house fires involving electricity last year were due to poor workmanship or any number of other causes, such as a rat chewing on wiring or a faulty appliance.

"We can pinpoint perhaps a particular electrical item. But we just can't determine whether it's failed internally, whether it's been a loose connection into the wall outlet, because there's just not enough [evidence] left to enable us to make that definitive determination."

The former fire investigator said one thing that could be contributing to the increase in electrical fires was the rise in the number of appliances inside the average house.

But poor workmanship by untrained handymen was an ever-present danger, and one that could increase as a result of Covid-19, he said.

"People have been at home during the Covid lockdowns, there's less money in the economy to pay the tradespeople to come in and in there's obviously a desire to save what money you do have and therefore people will attempt to do some things that ordinarily they wouldn't."

The head of industry body Master Electricians, Bernie McLaughlin, said some homeowners may be being led astray by regulations saying they could complete some electrical work around the house, as long as this was signed off by an inspector.

He said in reality, no inspector was going to do this.

"Should there be an ensuing fire or electrocution, the inspector will be liable. So it would be very difficult to find an inspector that would turn it off and put their own livelihood and license at risk."

As well as getting new work done by a registered and trained electrician, he recommended people such as Ogilvie's landlord get a check done on work already completed.

"We have our own certified testing regime called an 'electric check', and it's effectively a residential home based testing regime which will go through various factors to prove that the lighting has been installed correctly, that there's nothing illegal with regard to damp situations around bathrooms."

McLaughlin said for as little as $150, a homeowner could have piece of mind that they were not going to be accidentally electrocuted or have their house catch on fire due to shoddy electrical work.

The Electrical Workers Registration Board, which receives complaints about defective work, said most were not about homeowners but contractors installing heat pumps or spa pools who were taking on work beyond their level of expertise.

It recommended homeowners always asked to see a person's licence to carry out electrical work before allowing them on their property.