Archive for July, 2011

Electrical Tip of the Day: Portable Window AC Units – 5 things you should know

July 21st, 2011 No comments

The heat is on… which has us all looking for ways to stay cool.  For many people and many applications a portable window air conditioner is the only option for a good nights sleep.  While these appliances do provide some much needed cooling relief, they also present some significant electrical safety concerns.

Here are 5 things your should know when using or installing a portable window AC unit.


1) In an ideal install they should not be ran on extension cords – if you must use an extension cord make sure it is a larger gauge wire then the cord on the unit.

2) Many window AC units are designed to be ran on a general use 15 or 20 amp circuit – but some need dedicated lines just for the use of the AC.  Make sure you check the amp draw on the unit and the manufactures guidelines for safety before using.  Be careful plugging these things in to *just any old outlet* to avoid overloading a branch circuit.  It is never recommended to run more then one unit on the same circuit.

3) Check the cord and outlet – if they are getting warm then you are at risk of an overload, if they feel HOT to the touch then you are overloading some part of the circuit or the conductors. Also look for dimming lights and power outages related to the AC kicking off and on.

4) Old homes that still have ungrounded knob and tube wiring present a significant safety hazard. These old circuits were never designed to have high demand appliance loads on them. It is never a good idea to use a window AC on a knob and tube circuit.

5) Plug adapters… you know the little two prong “cheaters” that let you plug in a grounded cord into an ungrounded outlet. When it comes to window AC’s just don’t do this. There is a very good reason why these units have a ground prong on the cord.


Arc-Fault Circuit Interrupters… say what?

July 20th, 2011 No comments

AFCI Circuit Breakers


AFCI breakers are Arc-Fault Circuit Interrupters.    They are similar in appearance to GFCIs (Ground-Fault Circuit Interrupter) breakers and they first came into the market in 1999. They are designed to prevent fires from arcs (sparks) that are not a normal part of a circuit’s operation.  Normal and safe arcs occur in switches and in electric motors such as fans and vacuums.  They are generally very small or very short in time duration.  The devices that produce these normal small arcs are designed to shield and protect people as well as the surroundings from the arcs so there is no fire risk.  Dangerous arcs can occur when devices fail, cords are damaged or the wiring becomes faulty as often happens with receptacles using stab-in connections.

The original AFCIs were branch type units designed to trip on 75 amperes of arcing current from the line wire to either the neutral or ground wire.  They were required to be installed for all bedroom circuits with the 2002 National Electric Code but did not provide personal protection from ground faults so kitchens, bathrooms, and garages still required GFCI circuit protection.

The 2008 revision of the National Electric Code changed the requirements to include Combination Type AFCIs for all 15A or 20A circuits in a dwelling except kitchens, bathrooms, laundry rooms and unfinished basements, which still require GFCI protection.  The combination AFCI added additional protection for series arcing at 5A and personal ground-fault protection which trips the breaker at a 5mA level for ground faults while maintaining the original 70A parallel rating for line to neutral arcing.  AFCIs still protect the circuits from the traditional overloads, short circuits and overheating breakers.  The Code still does not require AFCIs for kitchens, laundry areas, bathrooms and garages since it requires the use of GFCI breakers or GFCI receptacles in these locations.  Adding AFCI breakers to feed GFCI receptacles is not recommended due to the fact that nuisance tripping can frequently occur.

All of the major manufacturers offer combination AFCI breakers so replacing older standard breakers with the new combination AFCIs is possible in all but a small percentage of applications.  The primary exception being the “cheater” breakers that feature two circuit in one mounting position that are typically used when a smaller load center has no spare positions for mounting new breakers.   Local jurisdictions and local codes vary, so always contact your local officials or local electricians for assistance.

On a final note, if the wiring in your home does not have the combination AFCIs and you have them added for the additional fire protection they offer, contact you r home owner’s insurance agent and let them know your electrical panel was updated.  You may qualify for a lower annual premium or other discounts which can help offset the cost of the upgrade.