Fire Hazards in Homes: AFCI

Most people have heard of GFCI before. They are those outlets with the little buttons on them to “test” and “reset” them. If you’ve had a home inspection or appraisal, there’s a good chance they recommended adding them somewhere.

GFCI are designed to prevent shocks. However, there is another safety feature that is not mentioned as often: AFCI.

AFCI stands for Arc Fault Circuit Interrupter. AFCI devices are designed to prevent house fires.

In our last blog post we discussed how loose wires can cause fires. Well, that’s true but we left part of it out.

The truth is that the melting wire itself is not directly responsible for most fires. Instead what happens is the connection melts and eventually forms a gap between the wire and the screw (might only be a few milimeters).

At this point, electricity “arcs” which is basically a spark jumping from the wire to the terminal (A more obvious example of arcing is a lighting strike, or when a shock happens with static electricity).

Arcing is actually what causes the majority of house fires. The spark is more likely to ignite nearby combustible materials such as wood, paper insulation coverings, etc.

A circuit breaker or fuse will NOT stop an arc. But an AFCI circuit breaker will. An AFCI is able to detect these arcs and shut power off, potentially saving your home from a fire.

It is true that some AFCI can nuisance trip, or trip when an issue is not actually present. But in general AFCI are a great safety feature for homes.

AFCI were first required in the early 2000s, and so most homes don’t have them. Fortunately, they can be added to most existing panels by a qualified electrician.

An AFCI breaker. AFCI outlets do exist, but breakers are more common as they protect the entire circuit.

A high voltage arc at a power station/substation. The distance electricity can arc is directly proportional to the voltage and current. An arc in a home cannot travel anywhere near this distance, but it can start a fire.

Sparks are essentially an arc. They are usually small in residential due to lower voltages, but can cause fires or harm to people.

Fire Hazards in Homes: Melted Wires

Electricity is dangerous, but not always in the way people think. Most people think of electrocutions, which is when electricity courses through somebody and stops their heart, leading to death.

But fires are another major hazard with electricity. One common way that an electrical fire can happen is when a wire burns up.

Wires burn up when they are improperly connected (loose) or have a compromised connection (typically oxidization or rust).

When a connection is loose it increases the heat which eventually melts and can start a fire. This has killed people.

In many cases, this is actually a very simple repair, although if the underlying components are damaged they will need to be replaced. If it’s just the wire, it’s a simple fix.

This highlights the importance of hiring qualified electricians to do electrical work—not the cheapest person you can find. It’s not worth your life.

Very badly burned up wire. This also shows two wires under a single terminal. This was common in older homes but is no longer allowed by code. This is typically not a difficult fix.

The breaker bus bar is badly burned. The panel should be replaced in this instance for safety.

The “brown” wire is actually white. It’s brown because the heat discolored it. You can see a black section closest to the breaker. This hasn’t gotten too bad yet and is an easy but urgent fix.