Can I use twin breakers in my breaker panel?

Twin, or ‘two-for-one’, breakers allow the connection of two, separately-protected circuits in the space of one standard breaker. Two circuit overcurrent protective devices (COPDs) connect to a single leg of the phase bus bar in the breaker panel, effectively doubling the capacity of the breaker panel in terms of number of branch circuits connected. The total power capacity of the panel does not change with the addition of twin type breakers (and is largely unaffected by what breakers may be installed — a common misconception that can lead to the wrong conclusion that a panel is overloaded simply because the Ampere rating of all breakers adds to more than the main breaker Ampere rating).

How do I tell whether my breaker panel accepts twin breakers?

Most breaker panels are rated to accept at least a few twin breakers. Some accept twins throughout the panel, and some accept no twins at all. The diagram inside the panel cover should indicate which breaker positions accommodate twin breakers (see photos).

See also:

• 200A service upgrade vs. panel upgrade for existing 100A service?

Advantages of LED lamps and high-efficiency lamps

It’s not just about energy savings: CFL’s, LED’s and other SSL types offer aesthetic, labor-saving, and special-application advantages

Compact fluorescent,  and LED and other high-efficiency lamps in the emerging field of Solid State Lighting (SSL) promise dramatic advantages in energy use and control convenience in homes, businesses and industry. Although high-efficiency has been the primary focus in promotion of these lamps, all the new technologies also claim significantly longer lamp life, as well as a variety of other advantages not widely reported.

Read on about CFL and SSL advantages relating to lamp life, power factor, and reduced fading from UV

How to recess a switch box or receptacle box in plaster-and-lath walls

The book Wiring Simplified has an excellent print guide with illustrations, for how to install beveled wallcases into plaster-and-lath walls. Since I install receptacles outlets and switches in old walls at least once per week in West Philly (Philadelphia, PA), I figured I might as well make my own guide using photos. Here’s my guide on how to recess a switch box or receptacle box in plaster-and-lath walls

What is a receptacle?

Also referred to colloquially as “outlet” or “power outlet”, an electrical power receptacle is a female connector for portable electrical loads such as lamps, power tools, small appliances — anything moveable, which could be anything from a night-light (with no cord) to an industrial kiln via cord-and-plug connection.

What is an outlet (power outlet)?

In professional electrical terms, an outlet is any accessible point in a wiring system. This can be for the purpose of connecting loads (as for receptacles and lighting fixtures) or simply for safe installation and maintenance of wires (junction boxes and condulette bodies used to make splices or to pull wires in conduit/raceway around sharp angles).

Residential Receptacle Types

15 Amp-rated grounding duplex receptacles Read more >>

Selecting recessed lighting housings, trim, LED options

What is recessed lighting?

Recessed lighting dates to the 1930′s, but appears most commonly in houses built or renovated after 1980. Like track lighting, it came in as a kind of construction fashion trend: the lighting method and different styles have their place, but can be over-used as a symbol of modernity or designerliness, where cheaper and time-tested lighting types can get the job done better.

A damp location recessed fixture lamped with new LED technology will not need a lamp change for up to 50,000 hours of lamp on-time.

To me, recess lighting at its worst screams: “Dallas“(TV show) or “cocaine”(a la Miami Vice) — in short, excesses of the ’80′s. Before choosing recess lights, consider a few gateway questions:

1. Do you want them to solve a particular lighting design problem, or because they’re fashionable or your neighbor just got them?
   Recessed lighting can offer the advantages of direct light to specific areas from lamps with high-quality optics, reduced glare, and minimalist styling that eliminates business from a ceiling. However, lighting has existed long enough that it is an architectural feature in itself, and well-chosen surface-mount lighting fixtures — including track — can contribute to a room’s aesthetic just as well as they may sometimes detract.
2. In retrofit installations (aka: ‘old work’ — renovations), you may have less choice about locating your recessed light housings than you might imagine. The finished look may be a magical disc that floats in the ceiling with no attachment business, but structural joists concealed by plaster/drywall may run dead-center to the location you want, and will in any case make layout and wiring of recessed lights time-consuming and/or messy. If you are installing more than a single recessed light without taking down the whole finished ceiling first, then be prepared to compromise on your ideal location.
3. The housings inside (above) the finished ceiling surface can invite drafts. Insulation Compatible (IC) housings may be nearly air-tight, but even these will increase air-flow between finished and un-finished spaces in your house, reducing the energy efficiency of your home.
4. Make sure you have a high-quality, flat surface on your ceiling (drywall level 4 or better), or else be prepared for gaps to show between trim edge and ceiling, where the trim sits across an uneven section of ceiling. Plaster ceilings typical of older homes will make a good trim fit difficult, as well as complicate any installation other than complete removal and re-installation of the ceiling. Recess lights look great in those drywall level 5-happy houses typified as the drug-lord mansion in Miami Vice. Read more >>

Troubleshooting dusk-til-dawn flood lights

Dusk-til-dawn flood lights may have any of a variety of configurations and features that could be involved in a failure. The simplest involve a fixture with photo sensor that interrupts (switches) power to the floodlight lamp holders when daylight is present. Other ‘enhancements’ such as outdoor motion sensing flood lights and dual brightness level settings may come at the cost of increased susceptibility to weather, mechanical and electronic failures (usually due to temperature extremes or else voltage surges from nearby lightning strikes, damaging circuitry inside the sensor assembly). Where possible, consider use of an astronomically-self-calibrating timer (see Intermatic), rather than sensor-based controls for outdoor lights. If photo-sensing, and especially motion-sensing, are critical or cheaper due to the wiring configuration of your fixture(s), then consider a whole-house surge suppressor to protect their sensitive electronic components along with those of consumer electronics and newer appliances inside the home.

A timer may be the culprit if your outdoor lights don’t seem to operate correctly in Spring or Fall: daylight savings time, your own pattern of being outdoors vs. indoors, and changing daylight hours could individually or cumulatively amount to the timer being out of sync with your lighting needs. The most common timer for exterior lighting is a 9″ x 5″ mechanical clock with set-screw timing points that trip a mechanical switch on and off. The Intermatic T101R has been a go-to classic for decades, but may be effectively replaced today by the astronomically auto-adjusting digital version for location in utility areas, or a more elegant wall switch timer that you can locate for convenient manual override to turn your floodlights on/off when the timer would otherwise prevail.

Read on to understand photo sensor dusk-to-dawn failure modes

Faulty receptacle grounding

Grounded receptacles require proper wiring methods and proper implementation of those methods, including compression wire nuts that chemically bond wires to each other, rather than wires just twisted together.

Electrical continuity for power wiring in buildings requires bonding conductors wherever continuity relies on more than one piece of conductor (wire). Bonding involves a chemical bond between separate pieces of conductor that will carry current.

Improper bonding of equipment grounding conductors in a receptacle wire box.

In this photo, the installer has used a common shortcut that may provide adequate grounding immediately upon completion of the job, but which will degrade over time, due to oxidation of the outer surface of the copper equipment grounding conductors. For copper EGC’s, oxidation only occurs on the outer surface of the copper. By creating a proper bond at the time of installation, oxidation cannot penetrate and interrupt the bond over time. More on properly bonding receptacle ground wires in a daisy-chained wiring topography >>

Frayed service cable / power quality

Frayed service cable / power quality

What type of electric service cable damage are you looking out for?

If you can see exposed aluminum strands on your service entrance cable, it has frayed to the point where you should replace it. Cost may vary from $750 – $2200, depending on your service capacity (usually between 100A – 200A for residential electric accounts) and the capacity of your replacement service (for those wanting central air conditioning, an upgrade from 100A to 150A or 200A will often be needed; subsequent solar PV or micro wind power installations over 5kW capacity may be cheaper to install if the existing service is larger than 100A).

More on causes and effects of worn electric service entrance cable >>

Fuse cabinet as distribution panel

Fuse cabinet as distribution panel

Many homes in West Philadelphia feature a distribution panel remote from the main service equipment. In older installations, this may be a wooden cabinet with a picture-framed wooden or glass-pane door, usually located in a stair- or hallway, and lined with a felt-like friable material that may be asbestos.

Several fuse-holder modules provide for branch circuit over-current protection. Unlike with modern wiring, the fuses may protect both the grounded (neutral) and ungrounded (‘hot’) conductors of 120V circuits, so a single circuit may have two fuses in it.

These fuse cabinets may not meet the demands of modern electrical usage

More on working with, or replacing old fuse cabinet type distribution panels >>

Polarity matters in AC wiring

AC polarity isn’t right, just because ‘it works’

Polarity in AC circuits doesn’t matter; until it does.

A common mistake of amateurs (and some experienced but untrained installers) is to assume that because house AC wiring is ‘alternating current’ moving alternately in two directions, the polarity of the circuit conductors has no significance. Most loads will in fact operate when wired backward (or connected to reversed-polarity receptacles), and the ‘it works’ test often is as far as some installers go in their understanding of proper installation.

Read on to learn the safety concerns with reversed polarity in AC wiring