Loose receptacles probably also dusty

If your receptacle doesn’t have enough tension to hold plugs securely, then you should replace it. Like any spring mechanism, a receptacle’s internal contactors will fatigue from repeated use (especially noticeable, for example, in this era of thronging laptop freelancers working from cafe public receptacles).

A receptacle with good socket tension should be able to support even a heavy ‘wall wart’ power adapter plugged in upside down so that the weight tends to lever down and outward from the socket.

If your socket tension is insufficient, arcing from a loose connection could start a fire (one example of the kind of arcing AFCI breakers aim to halt). Timely maintenance is especially important in homes, where the looseness is more likely due to age, which in turn brings the accumulation of combustible dust inside the receptacle wiring enclosure. Also, residential plug-in loads are more likely unattended when residents are absent from the home or asleep, so minor smoking from a receptacle that could easily be turned off may smolder on into full-fledged fire before anyone notices or a smoke detector sounds.

What to do if your whole house starts flickering electrical

1. Damage Control. Avoid using expensive equipment (like computers or flat-screens) on any circuit where you see flicker (that turns off with the same breaker as a light that flickers). Flicker is often due to a failing neutral connection, and eventual total loss of a neutral can put 2x voltage across the outlets in some wiring configurations. This can destroy electronics.
2. Try to identify at least one circuit (lights and/or receptacles with lights plugged into them, all controlled by a single circuit breaker) that does NOT flicker, ever. Most likely, a newer kitchen or bathroom circuit, or something maybe near the breaker panel in the basement. If you cannot find any circuits unaffected by flicker, call PECO for free service that will rule out a fire-damaged or otherwise loose connection on their lines. Look outside and try to tell whether your service drop from PECO lines comes in a) from overhead lines on the street, via a tap from the PECO lines that is independent of other houses (or shared with only one neighbor), b) via a common cable running along the back of all houses on your side of the block, or c) entering your basement from underground, via a big rectangular steel box.
3.  If your service drop is from overhead and shared down the block, the fire very likely DID affect you, and you can chat up neighbors to see if they’re having the same trouble, while you wait for PECO to confirm/deny this. If it is overhead but independent of neighbors or only shared by one neighbor, then the fire is probably irrelevant. Still, you may have a loose connection to PECO lines or there could be trouble on PECO lines that they can rule out for you, for free. Look up and down the block for signs of obvious damage to the PECO lines that you share with your neighbors.

   

   A run of 240V, single-phase utility lines behind a row of twins has come loose from its mechanical supports on one building. Resulting strain on splices may cause intermittent or arcing connections that would result in flicker for affected buildings.

   

   Corrosion and/or loose terminations at the service equipment could cause intermittent and/or arcing connections and result in flicker on alternating rows of breakers served by the loose/corroded conductor.

   
   
   
4. Connect a microwave, vacuum cleaner, or space heater and see if turning it on/off contributes to flicker. Does it affect more than one circuit, or just the circuit where you plug it in?
5. If more than one circuit breaker is affected, but NOT all circuit breakers, try to determine whether the flickering is affecting breakers on alternating rows of breakers. Because the twin (and opposite) phase conductors (aka ‘hots’) feed alternating rows down the two columns of breakers in your panel, only even rows or only odd rows affected would indicate that one, but not both, of the phase conductors somewhere between PECO and your main breaker has a loose connection at one of its terminals. It is rare for both phase conductors to go loose at the same time, so a ‘loose hot’ condition appears with this characteristic symptom of alternating rows totally out, or flickering.

Miswired bathroom fan, light, heater needs 14/4+Gnd (not 14/3)

DANGER! White used for switched-phase, bare used for current-carrying grounded conductor!

I encountered this thoroughly miswired switch location while attempting a ‘simple’ faulty GFCI receptacle replacement. The 20A GFCI circuit served the GFCI as well as a 3-in-one fan/light/heat control for the bathroom overhead fixture. Unfortunately, the 14/3 plus ground (black, red, white, and bare) cabling for the fixture was too small (#14 conductors rated for 15A, not 20A) and included only two phase (hot) conductors, whereas the three switched loads integrated into the fixture require three hot conductors.

Read more >>

Pull-chain switches don’t last anymore

Pull-chain switches don’t last anymore:

I have finally become fed-up with failing new-installed pull-chain switches from name-brand manufacturers. So I wrote a letter to one stating that Pull-chain switches don’t last anymore:

Troubleshooting AFCI breaker tripping

INTRODUCTION

AFCI breakers are so sensitive that I often hear of electrician complaints that they may be giving false alarms. However, I have installed more than 100 of them and only ever encountered one – maybe – that may have been tripping improperly. I’m not sure I could report as good a record for standard breakers, whose failure rate I’ve not monitored as closely (they cost 1/5 as much, for one thing).

Recently, I had the new experience of inadvertently using an AFCI breaker as a fake-grounded receptacle tester. Initially, I was chagrined to have to extend my work to troubleshooting a ‘perfectly functional’ circuit, but it turns out this was a dangerous circuit and the AFCI ‘fake-ground detector’ is a good tool to keep in the proverbial chest, and one more reason to use these breakers as much as possible, even on existing circuits, in spite of their expense. Goto more on troubleshooting AFCI circuit breakers…

Consequences of over-lamping

Few lampholder sockets, except for outdoor fixtures or three-position floor lamps, are rated to accommodate the all-too-common 100W incandescent light bulb (lamp).

This photo shows what happens over time, if you use 100W incandescent lamps in the wrong fixtures (most of which are rated 60W or 75W maximum). Incandescent lamps are being replaced by CFL’s and LED’s because 90% of the energy they consume is invisible heat radiation. The heat destroys lamp holder screw-shell sockets and the wires leading to them.

In the photo, the insulation around the screw-shell has become brittle from baking by the 100W lamp. The screw-shell itself makes electrical contact via rivets at the base, which is cheap aluminum and has also baked its way loose of the rivets. The result is a familiar problem in old houses with old fixtures: a slowly-worsening problem of lamp flicker and intermittent lamp failure. The intermittent, poor contact at the loose rivets can generate heat from arcing at the connection, and could ignite wires and start a fire. Read more >>

Cable track lighting systems are elegant, only good for 300 Watts

12V LED lamps save an overloaded track lighting system

I recently encountered a fine mechanical installation of a cable track low voltage lighting system that was electrically overloaded. The cable track cable is good for 300W. That’s six (6) 50W lamps. Many installations will benefit from new high-efficiency LED lamps that provide similar light levels with improved optics at only 10W each. So if you have 40 linear feet of cable track zig-zagging over a public gathering area, you easily position 3 or even 6 lamps per 10′ section, whereas with 50W halogen lamps, each 10′ section would get only one or two lamps every 10′ section.

More on overload for low voltage lighting systems >>

Bell transformer short: electrical burning smell in house

Troubleshooting by phone saves customer service call expense

I recently had a call from a concerned customer, about an electrical burning smell in the house, after demolishing their own kitchen in preparation for a renovation and remodel. Sweeping up afterward, they saw some slight sparking on old wires that had had a lighted doorbell button connected.

With a few more questions, I quickly steered her into the basement and toward the following theory:

• The bell wires had become crossed (shorted).
• Short-circuit current through the bell system transformer operated the transformer at high current for extended periods (whereas it is designed to operate through the resistance of the bell button lamp when at rest, or the bell motor/chime when the button is pressed — momentarily not continuously).
• The bell transformer windings (tiny copper insulated by a tiny layer of insulation to allow the windings to pack densely together for maximum effect / minimum size) burned through their insulators and/or opened the circuit by burning a winding conductor out like a lightbulb filament. This was the burning smell.

Subsequent inspection bore out the theory, and the customer has had the transformer disconnected from the circuit by a local handyman friend, rather than call for outside service.

Background:

Bell, intercom, and thermostat/control systems typically operate on low voltage AC circuits (under 48V), allowing the use of freer wiring methods, including smaller wires (16-22 guage), exposed wiring acceptable, and splices without junction boxes acceptable. Bare skin will not pass current (permit a shock) below 70V (women typically can’t be shocked below 85V and men below 90 or 100V), and building structure is similarly safer from low-voltage wiring than 120V household power wiring.

Transformers energize the bell/control systems using power from the household 120V power system. AC on the transformer input coil induces a ratio of AC voltage on the transformer output coil corresponding to the number of windings in the two coils. A typical winding ratio of 10/1 yields 12V AC from the 120V AC input.

Since the failure mode of transformers (usually due to a short circuit, or continuous rather than intermittent use) is to open the circuit, even short circuits on the low voltage side aren’t likely to present a fire or personnel safety issue. Typically, the transformer acts as its own circuit breaker.

Troubleshoot circuit problems in old Philadelphia home

A recent circuit troubleshooting job at 44xx Locust St. probably started when a plug-in electric space heater overloaded a knob-and-tube circuit serving a dozen locations besides the one where the heater was connected. Space heaters typically consume 100% of permissible circuit load, although when connected to a knob-and-tube location, they may be sharing with a dozen or more lights and other receptacles.

The overload might have had no consequence if a wire-nutted splice in a basement ceiling junction had been better made-up. Unevenness in the wire twist combined with absence of any metal bonding sleeve inside an old ceramic wire-nut probably allowed oxidation to partially insulate the spliced wires from each other. When the heavy heater load subjected this poor connection to overload, the connection failed entirely — probably due to arcing and burning of the tiny contact-points that remained. A problem such as this could be identified before it manifested as a complete fault, by use of a loading receptacle tester to analyze voltage drop under a load of 12A or 15A (see FAQ-Voltage Drop by SureTest(TM)).

More on causes and fix for circuit overload in an old West Philadelphia house >>

Twisting wires does not bond them

Most common with equipment grounding wires, twist-only wire termination or splicing can result in dangerous problems, because the connections can and do fail. Failure in a grounding wire will likely be in the mode of ‘lightning surge damage throughout the home was considerably worse due to poor, twist-only connections, but would have been bad either way’ or ‘grandma died of a heart attack when the ground path didn’t allow sufficient current to flow to trip the circuit breaker and open a fault from the ungrounded (‘hot’) conductor to the exposed metal housing of the washing machine’.

Faults due to improper twist-only wire terminations in the actual circuit conductors may be even more dangerous — especially if a similarly slack approach was taken with the grounding wires.

Read more >>

How to not burn down your old house with a plug-in space heater

It’s that chilly, blown fuse and tripped breaker time of year again.

Based on my experience as an electrician serving residential customers, electric space heaters cause more electrical trouble tickets in Philadelphia than any other single connected appliance or event. With the cold weather comes the seasonal task of explaining to homeowners and tenants that they simply should not be using their space heaters — at least not unless their entire house has been rewired top to bottom, or until they have their breaker distribution panel mapped and make up a plan to balance loads with extreme care. The difficulty is that knob-and-tube circuits remain in any older (pre-WWII) home that hasn’t been rewired, and that these circuits tend to serve a dozen locations — much too much to be able to handle the additional load (overload) of a space heater.

The risk of fire from a circuit overloaded by a space-heater is like the risk of cancer from smoking: you may have done it for decades without obvious damage, but cancer/fire could strike any day. You need to find a way to pay for a better solution than putting everything you own and everyone you love at risk just to stay warm.

If your house lacks dedicated circuits appropriate for space heaters, then it may be worthwhile to just keep the central heating system’s thermostat dialed comfortably and/or invest in weatherization to avoid the risk of catastrophic circuit failure and fire, and convenience issues such as 90% of the lighting in the house being unsafe to use after a near-fire on the shared circuit where you plugged in a heater. Space heaters largely just shift heating costs from gas or oil to electric, rather than save money, anyway.

But I need to use my space heater, because…

Read further on steps to avoid fire hazard from electrical overload

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

Repairing outdoor outlets and wiring methods

Botched DIY electrical installations are common enough indoors; outdoors, the ways weekend installers can go wrong multiply, as do the number and frequency of fatal consequences. People tend to underestimate the forces of nature, which include driving rain, ice damming, freeze-and-thaw cycles, relentless UV radiation, temperature extremes, corrosion, and more. Outdoor/exterior installations also may be accessible to strangers, unattended children, and strangers’ unattended children, exposing the building owner to lawsuits if something does go wrong. Finally, people outdoors are more at risk to electric shock and electrocution because they are on the earth, in the earth, or likely to be touching earthed objects (grounded).

Read more >>

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 >>

Why do rodents chew wires?

I have found that chewed cables tend to be the ones that were not properly strapped along solid supports. It’s widely reported that rodent’s teeth never stop growing, and therefore require constant grinding to keep them from growing long enough to ‘hamper the hamster’. But why do they chew wires that could kill them?

I recall a recently published article suggesting that rodents chew because evolution selected for ‘neurotic’ traits that helped ensure the rodents have no difficulty with the will to keep their teeth properly ground down to size. Perhaps for parallel reasons of natural selection for reproduction, many of us don’t have sex to make babies (necessarily): we obsess about it and we enjoy it. It seems likely that rodents don’t chew to grind their teeth. They may enjoy chewing, it may be a neurotic itch or symptom, and it may be both. Whatever may be in the rodent’s brain, the result is that their teeth stay short enough that they can function.

On any given length of chewed wires, the most heavily-chewed portions are always the ones hanging in mid air — right at mouth height for everyone’s favorite furry rodent. Picture a neurotic character, your rodent, pacing up and down the length of a dark, dusty attic on a cold, windy night. Which cable are they going to get involved with? The one they trip over, over and over again, or the one their distracted consciousness probably doesn’t even register, because it’s neatly strapped to the building’s structural members?

In new construction, the National Electrical Code (NEC) requires that all cables be fastened snugly along solid supports where possible. In retrofit wiring, cables fished behind finished surfaces cannot be secured, so older homes will tend to have wiring that is more vulnerable to rodent chew. More on how neat wire runs prevent rodent chewing damage >>

Panel bonding jumper missing / 200A Service

A green-colored screw should thread into the heavy gauge steel of this 200A service panel enclosure, securing the bonding jumper. At the center of the highlighted area in the photo, one can see that the screw was either removed or never installed.

This threaded ground bonding location ensures that the metal panel enclosure remains at zero voltage to the building and service grounding systems, and helps ensure that a low-impedance path for fault current on the panel enclosure will trip a breaker before serious damage occurs. A poor connection here could result in a high-impedance path for fault current. An ungrounded (‘hot’) conductor could contact the panel enclosure and discharge to ground through this poor connection at relatively low levels of current not sufficient to trip the breaker protecting the circuit. At least two hazards would result:

1. The connection missing the screw could heat up and melt adjacent wire insulation, causing more trouble, or ignite the wooden surface on which the panel is mounted.
2. The panel enclosure would remain energized until the fault is cleared, and could electrocute someone.

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 >>