When New and Old Collide

Old electrical systems can be safely added onto if the following considerations are followed:

• You have room in your service panel or fuse box for additional circuits.
• Individual existing circuits aren’t fully utilized and can carry an additional load.
• The wiring and insulation of these circuits are intact and not worn.
• You properly join new wire to old.
  

You can’t see inside your walls and observe how every receptacle, switch, and light has been wired, but you can get an idea if an addition has been made to the original system.Look for the following telltale signs:

• A receptacle or switch style that doesn’t match the others in your house (The cover plates also might be a different style.)
• A fixture located in an odd place such as a crawl space
• A receptacle that isn’t as evenly spaced as others
• A receptacle that is cut into a plaster wall while all the others are cut into the baseboards—a common feature in turn-of-the century homes
• Any switch or receptacle that is surface mounted on a wall rather than cut into the wall

Do you have unfinished attic or basement space? These are prime areas for added fixtures to be tied into existing wiring and should be checked thoroughly.

Good Wire, Bad Wiring

An original service of knob-and-tube wiring, if properly installed, is and can remain a safe electrical system. Left alone, it would satisfy the electrical demand for which it was designed without any problems.
When it isn’t left alone, or when the loads increase and stretch the system’s capacity, the problems and hazards begin. Add-ons are pretty easy to spot, especially those done by homeowners. Dead giveaways include …

• Sloppy installation.
• Loose, unsecured wires.
• Wires running across the edge of floor joist rather than passing through them in unfinished basements.
• Improper taping at connections through the use of unapproved materials such as masking or adhesive tape.
• Mixing two different gauges of wire on the same circuit.

Other issues include worn and frayed insulation and brittle wire ends where they are attached to loads or switches. This problem is exacerbated as the wire ends get bent and unbent when switches, receptacles, and light fixtures are replaced over the years due to general wear and tear or the desire for something new.

Jump Up to 200 Amps

If you’ve got a small service, say up to 100 amps with a fuse box, in a two-story house and you’re thinking of upgrading to circuit breakers, replace it with a 200-amp panel. Don’t argue about it or debate its need, just do it. The last house we owned was a 1924, three-bedroom, one-story bungalow on a street of one-story bungalows. You could easily maintain that it only needed a 125-amp service, but a funny thing happened as Seattle real-estate prices headed toward the stratosphere: These one-story homes started becoming two stories. Owners decided it was more cost-effective to stay put and add on rather than to move. Five of our former neighbors on one block did this very remodeling to their homes. My point is that you cannot predict future needs. Given the relatively small cost difference between a 125-amp service and a 200-amp panel, there’s no point in installing the smaller service in a two-story house. One exception to my 200-amp rule is the presence of gas appliances. Our first house, for example, was adequately serviced by a 125-amp panel because we had a gas furnace, water heater, stove, and clothes dryer. As a result, the biggest single electrical loads in the house were the refrigerator and the washing machine, neither of which were huge draws on the system.

Do You Need to Replace the Existing Circuits?

Installing a new 200-amp service panel in an older, two-story house, replacing all the existing circuits, and adding new ones to bring the entire system up to code—all this is an expensive proposition. The service alone can cost roughly $1,800 to $2,000. You can easily spend four times that amount wiring the house, depending on its size and the complexity of the new system. I hesitate to quote figures because every house is different, as are local labor rates, but an electrician can give you a ballpark figure, which is subject to change when an actual estimate is drawn up. Some people will replace and upgrade just to be on the safe side, while others should replace and upgrade. The following are signs that you should consider changing your electrical system:

• An undersized service (60 to 100 amps for a large, two-story, all-electric house)
• An insufficient number of circuits
• Too few receptacles and switch-controlled lights
• A lack of GFCIs
• Overloaded circuits with fuses that burn out regularly
• Frayed or deteriorated insulation on your current wiring Too often, homeowners ignore the basic mechanics of a house (electrical, plumbing, and heating/air conditioning) when remodeling and pay too much attention to aesthetics, such as cabinetry, painting, and floor finishes.

It’s easy to understand why: These are characteristics we see day after day. No one sees the new, modern, sheathed cable running through the walls to equally new grounded outlets, all of which are nicely distributed on properly sized circuits. I can’t begin to count the number of older homes I’ve been in that were beautifully redecorated but still only had one or two receptacles—and old receptacles at that—per room. There’s no excuse for living in an underpowered house as we begin the twenty-first century.

Wire Systems Old and New

A main difference between old electrical systems and new ones is the presence of a grounding conductor in contemporary wiring. Modern cable contains all three wires—hot, neutral, and ground—wrapped in protective thermoplastic insulation. Your house might have cable running through it rather than the old knoband-tube or metal-wrapped BX cable systems, but this is no guarantee that it’s got a grounding conductor. Cable installed in the 1950s only contained a hot wire and a neutral wire. The only way you’ll know for sure with your own cable is to check your electrical panel. You’ve already read that old wiring isn’t necessarily bad wiring, with the (sometimes) exception of BX cable, which can become damaged and be conducive to short circuits. The abuse usually occurs later as it gets hacked into. Replacing an entire system is expensive. New services installed in older homes usually incorporate some of the existing wiring into the new panel (unless it’s judged to be too corroded or unsafe). You and your electrician need to decide …

• If you can add any loads to your existing system.
• The compatibility of your current wiring with a new service panel.
• Whether your system is safe given its current usage.
• The practicality of completely rewiring your house.
• The cost versus the benefits.

What is GFCI — Ground-Fault Circuit Interrupters

The code requirement to install GFCIs has been a real lifesaver for homeowners. One government statistic suggests that a GFCI installed in every home in America could prevent more than two thirds of all residential electrocutions. A GFCI measures the current flowing into the outlet through the black or hot wire and the current outflow through the neutral or white wire (see the following figure). If the GFCI detects any difference greater than 7 milliamps, it shuts off the current. Why? Because any difference in the current is an indication that the current is somehow shorting or “leaking”—maybe through you! It might be a short in an appliance such as a hair dryer or an electric mixer. These are dangerous situations, and a GFCI will shut down far faster (in as little as 1/40 of a second) than a standard circuit breaker or fuse.
An older home may or may not have GFCIs, but it can be retrofitted with them. A GFCI won’t always prevent an initial shock, but it does prevent a lethal one. The current NEC calls for GFCIs to be installed in a number of locations, including …

• Bathrooms.
• Kitchen counters.
• Outdoors.
• Garage walls.
• Unfinished basements and crawl spaces.

Why have these areas been singled out? They all have something in common: water or water pipes, both of which are good at seducing a current away from its righteous path back to your panel or fuse box to take a trip through your body instead. There’s a reason why various cads in the movies get knocked off while in the bathtub when an irked female character throws a plugged-in curling iron into the water. If you use a defective hair dryer when touching the water faucet in your own bathroom, you’ll be glad you have a GFCI installed.

A modern electrical system will have GFCIs in the form of either outlets or breakers, although the latter are more expensive. The presence of a GFCI in an old system is a demonstration that a past owner was concerned enough to attempt at least a partial modernization of the system.

Fixing Electrical Equipments with Friends?

You’ll be testing your circuits one at a time. It’s just a matter of flipping a breaker or removing a fuse, observing what goes out, and writing it down. This means every light will have to be turned on, and every receptacle will need something plugged into it. This is where the lights and radios come in. It’s important that you know where every receptacle and odd light is located and that you account for all of them. As previously mentioned, this job is easier to do if you can fill up your house with some friends. As you turn the power off one circuit at a time, they can yell out what went off, and you can write it down in your notebook. This can be a fun project in a big house with people running and shouting as lights go off all over the place. Carefully write down everything as specifically as possible and redo the list later on your computer. Print a list to attach to your service panel or fuse box, and maintain the file on a disk to record new circuits as they are added or old ones as they are changed.

Know Your Circuits with a Circuit Map

Electricians follow the minimalist school of writing: They write as little as possible when listing the circuits on the form inside the service panel door. An electrician will write “Lighting circuits,” for example, across the space designating one or two specific breakers. That’s all well and good, but a more useful description would say, “Ceiling lights in master bedroom and north bedroom, in second-floor hallway, and at top of stairs.” These written descriptions need more room than most factory-supplied lists provide, unless the writing is very small.

In a new house, the electrician’s list usually is adequate because the wiring is so straightforward. In an old house, however, the list needs to be more specific, especially if past homeowners have added their own electrical marks when they lived in your home. Every owner has different needs, and they manifest themselves with receptacles, lights, and switches in places that will make no apparent sense to you but are perfectly logical for someone else. These include lights in crawl spaces, switches on attic rafters, and receptacles in closets. You don’t need to know their history, but you should know which fuse or circuit breaker controls them, especially if they are tied in to the middle of a circuit and can potentially cause problems. Drawing your own circuit map can be done alone, but it is best done with some helping hands. To come up with your map, you’ll need the following:

• Paper and pen for recording
• Lights and radios to plug into receptacles
• Extra people spread around your house

Circuits and Runs

Circuits can be divided by type:

• General-purpose or lighting circuits
• Dedicated circuits
• Small-appliance circuits

Lighting circuits include most receptacles in living areas other than the kitchen, bathrooms, and workrooms. This is appropriate for most receptacles because we generally use them for small loads such as floor and table lamps or clock radios. Some receptacles will only be used for night-lights; others might rarely or never be used. Even light fixtures have varying loads depending on the wattage of their lamps. They can vary from 25 watts to 150 watts.

What happens when you plug in something larger such as a room air conditioner? What if you have a water heater or an electric range that also requires large amounts of current? These loads call for dedicated circuits, which are so-named because they only supply power to one specific load.
Dedicated circuits include those for …

• Major appliances.
• Refrigerators.
• Computers.

It’s easy to understand why a major appliance needs a dedicated circuit, but what about refrigerators and computers? Even a large refrigerator-freezer combination is rated at about 500 to 700 watts, and a computer is far less. (My notebook PC is a minuscule 36 watts.) These fall into a different category of dedicated circuits that aren’t based on a demand for electrical current but on their specific activity. It isn’t critical for your refrigerator to be on its own circuit from a power-demand standpoint, but if another load somewhere else on the circuit’s run trips the entire circuit, your refrigerator will shut down, and you will be looking at a lot of spoiled food. Some jurisdictions codes require that the refrigerator be on a dedicated circuit.

Computers don’t store food, but they do store your data. Most people readily agree that we should back up and save our documents and spreadsheets while we’re working on them, but then we cheerfully continue working without doing either.

Amps, Watts, and Wire Gauge Working Together

You remember that amps, or amperes, are a measure of an electrical current’s strength or flow. A watt measures the electrical power itself. That is, it measures the amount of electricity consumed by an appliance or another fixture as it converts the electricity into something useful to us. A circuit is sized to allow a certain amount of electricity to run to a given number of loads.

The loads are measured in watts, which is why you can only have a certain number of receptacles and lights on a circuit. Too many running at once demands more juice than the circuit can safely provide before a protective device in the form of a circuit breaker or fuse steps in like a responsible bartender and cuts you off.

The amount of current carried to the various loads also is determined by the size of the wire running between the service panel and the loads. If your wire is too small for the amount of current the load is demanding, it will have a high resistance and will overheat. This is okay for the heating element in your toaster but not for your house wiring. A 20-amp circuit, which usually runs small appliances, requires No.12 wire. Many electricians recommend No.12 wire as the minimum size wire for residential use, even though the code accepts No.14 wire as the minimum-size conductor for branch circuit wiring.

Branching Out to Break Up the Load

You could connect all of your 120-volt electrical loads—lights, bedroom receptacles, the refrigerator, and so on—to one big circuit breaker, and they would still function. Replacing a broken switch or installing a new light fixture then would mean turning off all the power to the house rather than just the power to one particular room. If your housecleaning service trips this giant breaker with a new 55-horsepower industrial vacuum cleaner while you are out of town and is afraid to reset it, you can kiss that frozen Copper River salmon in the freezer good-bye.
Electrical current is broken down into individual circuits—called branch circuits—for safety and convenience. You don’t want the entire house to go dark because a GFCI in the kitchen tripped due to a faulty appliance. Each circuit is designed to carry a certain amperage and to provide enough current to meet the wattage demands of receptacles, lights, and appliances. The following figure shows a standard residential distribution of circuits.
A circuit is laid out logically, or at least it should be. This means that a 15-amp lighting circuit will control lights in, say, three continuous rooms rather than in three rooms at opposite corners and on different floors of the house. Several forces work together to help a circuit do its job safely.