Q: Recently you advised a correspondent on upgrading the electrical system in an older house. You recommended that he upgrade to a 200-amp main electrical panel. What is this based on? Is 200 amps the new baseline standard for residential electrical service? How would you describe the typical electrical service standard for new or remodeled houses?
A: The National Electrical Code (NEC) governs the size of the electrical panel for new homes or remodeled homes. There are various versions of the NEC. Check with your local building department to see which version is followed in your area.
If you’re considering doing some electrical work on your home, please heed this word of caution. Electrical work is not for the novice do-it-yourselfer. While it’s certainly possible for an amateur to add an outlet or replace a light switch with a dimmer switch, doing much more probably means hiring a licensed electrician.
We’ve noted that Bill was the electrician and Kevin was the plumber when we built Kevin’s house and remodeled Bill’s. Both of us had pretty extensive experience before tackling these projects, and we studied up before moving forward. And, on all these jobs, permits were pulled and our work was signed off by building inspectors.
If you decide to tackle an electrical job, consult your local building department and get an electrical permit before starting work. Have the job inspected at the appropriate intervals dictated by the inspector.
Because modern homes us a number of energy-hungry appliances, a 200-amp panel is the minimum we’d suggest. This size panel will adequately serve an average home and give room for some upgrades.
The total amperage of the branch circuit breakers serving the house should not exceed the amperage of the panel.
The load needed to serve the electrical demands of the devices in the house dictates panel size. Modern appliances such as electric cooktops, ovens, clothes dryers and air conditioners, as well as mixers, hair dryers and so forth, can eat up panel space in a hurry.
Multiple lights and most outlets can be run on a single circuit. But devices such as microwave ovens, cooktops, ovens and clothes dryers require a dedicated circuit.
Here are a few rules of thumb when thinking about the electrical requirements in your house:
1. Wire size is counterintuitive. The larger the gauge number, the smaller the wire. Eighteen-gauge wire is smaller than 12-gauge wire. The larger the wire, the greater the load it can handle safely without getting hot or causing a fire.
2. Generally a 14-2 Romex cable will serve most outlets. This means two insulated 14-gauge wires and one bare wire encased in a rubber sheath. The black wire is the "hot" wire; the white wire is the neutral wire; and the bare wire is the ground wire. It’s suitable for loads up to 15 amps.
Vacuum cleaners and lamps operate just fine on this amperage. Most home plug circuits are wired with 14-2 Romex that supply up to eight outlets per circuit. Depending on the usage, a couple of fewer outlets per circuit might be in order.
3. Generally, outlets serving the kitchen and dining room should be 20-amp circuits wired with 12-2 Romex. This is because these circuits will likely take appliances that draw greater amperage.
4. Outlets and switches within a certain proximity to a sink or other water source must be protected by a ground fault circuit interrupter (GFCI). A GFCI breaks the circuit even when a minute amount of water is present. This safety device prevents electric shock and in extreme cases prevents death. Plugs installed in basements, garages, outdoors and bathrooms also require GFCI protection.
5. Electric dryers require a 30-amp outlet protected by a 30-amp circuit breaker, while an electric oven mandates a 50-amp and 8-gauge wire protected by a 50-amp breaker.
6. It’s important to size circuit breakers for the wire size they serve. If a 14-2 cable is run from the panel to the outlet, then a 15-amp circuit breaker is the largest that can be used to protect that circuit. If a 12-2 cable is run from the panel to the outlet, then a-20 amp circuit breaker is the largest that can be installed to protect the circuit.
Back in the day when many houses used fuses it was not uncommon for unknowing homeowners to replace a 15-amp fuse that was constantly failing with a 20-amp fuse. This mistake created the risk of a wire overheating and causing a fire.