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Arc Fault Circuit Interrupters

Dear Mr. Electrician: Why am I required to have my new house wired with Arc Fault Circuit Interrupter circuit breakers?  They cost much more than standard circuit breakers.
Answer: Arc Fault Circuit Interrupter type circuit breakers and receptacles (AFCI's) provide an additional level of protection against fires.  Electrical arcs from loose connections create heat and sparks.  If combustible materials are nearby, a fire could erupt.  Arc Fault Circuit Interrupters protect us from potential fire starters that we cannot see.

Many residential homes have wood frame construction.  The electrical switch and receptacle boxes in the walls are attached to wood framing members.  The electrical wiring runs through the wood framing.  Wood is a combustible material.  If arcing is in contact with the wood for an extended period, it is possible that a fire may start.

 

An electrical arc can be caused by lightning of course and your grounding electrode system, if it is in good condition should be able to handle that.  However other causes of arcing are usually not as obvious until some damage or a fire takes place.  For instance, an electrical receptacle with a loose connection may be fine until one winter you decide to plug an electric heater into it.  The heater uses a lot of current to keep you warm.  With the extra load on it, the loose connection that was fine for a few years now arcs each time the heater is on.  This can cause damage to the receptacle, the wiring in the electrical box and wall, and even the heater plug and in addition the potential for fire is high.  If combustible materials are near by such as drapes and curtains, bedding or even furniture, a fire can start whether you are home or not.      Top 

Other Issues That Can Cause Arcing and Heat:

- Loose or broken plugs or cords on appliances and lamps.
- Nicks in the house wires and/or the wire insulation that occurred during the original construction or a rennovation thereafter.
- Worn out electrical receptacles that do not hold the plugs in tightly.
- Frayed insulation on appliances and lamps.
- Worn electrical switches.
- Very old electrically powered appliances where the internal insulation has degraded.

Another possibility for wiring getting damaged is from a major redecoration or renovation project where the old existing wiring is disturbed.  A small unnoticed problem that occurred during the original renovation may not manifest itself into a major hazard until months or years later.  Existing wiring is best left alone in older houses.  Like everything else in a house, wiring ages whether you use it or not.  However this does not mean that you should replace every wire in your house after so many years.  The wiring should last the life of the house as long as it is not disturbed and minor maintenance is performed every few years.

Maintenance such as tightening all connections in the circuit breaker panel and at all switches and receptacles will help to prevent arcing and heat.

Articles 210.12, 440.65, 550.25, and 406.4(D)(4) in the National Electrical Code pertain to the requirements for arc fault protection.  Replacement receptacles must be tamper resistant in addition to any AFCI reqirements.

Dual Function circuit breakers and receptacles are available.  A single dual function device can provide arc fault protection and ground fault protection.

Homes with aluminum wiring that was originally installed in the 1970's should have already had steps taken to its wiring to prevent the excessive arcing that it is known for.  See my advice on preventative measures for aluminum wiring by clicking here.

For those of you who want to learn everything about AFCI's and why they are important, you can read the white paper posted by Schneider Electric.  It contains much good information with photos & illustrations.     Top

 
 

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Updated April 12, 2018

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