A new cheese case dedicated receptacle for Fair Food Farm Stand

Outstanding purveyor of local food,  Fair Food Farmstand needed a new equipment receptacle to supply power for a new cheese case to support expanded offerings in delectable cheeses.

In developing a proposal for the work, I

• Mapped the existing circuits for this vendor’s tenant space at Reading Terminal Market in downtown Philadelphia.
• Developed design including a new, GFCI-protected 20A circuit to serve the cheese display case, as well as new GFCI protection for a pre-existing circuit extended to make it more convenient where used most frequently.

Feeds to the new equipment receptacle, pre-existing circuit, and extension location had to be drilled through Reading Terminal Market’s century-old barrel-vaulted brick-and-concrete floor — an 18″ penetration just within range of my tools in stock.

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

Modern Kitchen Renovation in a West Philly Twin

New counter receptacles and disposal plus extension of an existing lighting fixture circuit to one new location, and replacement of out-dated fixtures combined with new cabinets and floor to create a new kitchen at reasonable cost.

Tenant metering for basement water heater installation

Tenant metering in small apartment buildings (up to 5 units) can encourage energy conservation by tenants who may otherwise ‘get the full value’ out of their utilities-included lease agreements.

Often, the original installation relied on common heating/cooling (HVAC) equipment, and has not provided any breaker positions at the basement service entrance, for adding separated HVAC appliances later.

Upgrading tenant service disconnect equipment to a small distribution breaker panel with main/service disconnect may solve the problem. Since power to the disconnect enclosure may be cut during servicing, by pulling the unit’s individual meter, the cost for the upgrade may be reasonable ($150 each, plus permitting).

As a case study, the following gallery depicts work that:

• Added a 4th, ‘house’ meter/service to an existing 3-meter installation.
• Separated 1FL tenant and ‘house’ (common areas) circuits into respective main disconnect/distribution breaker panels.
• Upgraded 2nd and 3FL service disconnects to disconnect/distribution breaker panels with 2 positions/4-circuit branch circuit capacity each.
• Moved HVAC 110V circuits (controls, small circulator pumps) from the previously-combined 1FL / House panel to the newly-created breaker positions in the upgraded 2FL and 3FL distribution panels.
• Added 30A, 220V appliance circuits each, to 1FL, 2FL, 3FL distribution panels, to supply separately-metered electric hot water heaters.

Recess lights installed with minimal plaster repair

Recess lights installed with minimal plaster repair:

This project added five recess lights to the living and dining rooms of a 2-story West Philadelphia twin. The work involved working carefully within the cavity of a fine solid-wood pocket door (common in Philadelphia’s historic homes), and fishing new circuits through multiple joists without opening the finished ceiling for access.

Retrofit ceiling lights can be a challenge because a single circuit feeds multiple locations daisy-chained together — through two or more solid joists that must be drilled and fished ‘blind’ using a long, flexible drill bit. In older homes, the plaster of the ceiling, and the supporting wood lath above, make up a thick, uneven surface not well-suited to ‘old work’ or ‘retrofit’ housings, which are designed to clip to the uniform manufactured surfaces of wallboard (drywall).

Additionally, getting circuit conductors into the ceiling from a switch location will usually require at least one L-shaped cutout in the wall and ceiling finish. When considering a lighting retrofit project, note whether you have crown moulding, since this may be damaged when removed and replaced — and will certainly need to be re-painted.

Since recess lights typically benefit from being dimmable, consider early whether you will want to use CFL lamps (still not satisfactorally dimmable as of this writing, despite any manufacturer claims), or spend additional for dimmable LED’s (including housing- and trim-integrated types for recess lights), or take your chances on long-term availability of incandescent/halogen replacement lamps.

See also:

• Selecting recessed lighting components
• 3rd Floor lighting upgrade with recessed lighting (via attic crawlspace)

60A Main Lugs Only (MLO) Distribution Breaker Panel (DP)

This project is a rewire of a 2-story row home in the Art Museum district of Philadelphia, with an expansion of breaker panel capacity via a new, 60A-rated MLO distribution breaker panel (DP) located at the opposite end of the basement from the service equipment/main distribution breaker panel (MDP).

Breaker panels

may sometimes be referred to their grandfathers in residential electrical, the ‘Fuse Panel’. Also, on a more technical level may be referred to as “Distribution Panel”. And, getting more technical, the first type of computers were known as “switch boards”. Modern day Breaker Panels draw on there design from the earliest Switch Boards.

Fun Facts:

• The first true Computer Engineers were women whom operated and maintained the switch boards for heavy artillery during World War 2.
• The computing power of all of the allied forces of World War 2 combined would be equal to the computing power of an electronic greeting card.

Resources:

See also:

Wikipedia- Circuit Total Limitation

Wikipedia - Distribution Board 

Home Depot – Breaker Panels & Circuit Breakers

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

Installing baseboard receptacles

For this installation of baseboard receptacles throughout the 2nd floor of a 4-bedroom home on Kingsessing Ave. in West Philadelphia, I ran 1/2″ EMT out of basement foundation walls, up the 2-story twin’s exterior and then branching via UF cable to individual baseboard locations to serve window air conditioning (window AC) units, or other high-priority grounding / high priority power quality loads, such as computers or entertainment systems to be protected by multi-outlet surge suppressors.

EMT tubular conduit (raceway) provides physical protection where the wiring method is exposed just above grade coming out of the basement. Type UF cable provides sunlight and weather resistance run exposed outside the 2nd floor. Although this wiring method minimizes intrusion (and possible plaster damage that can involve dust and dusty repairs), running exterior wiring also involves work on ladders, and can often cost more, even though it appears simpler.

Note the number of tools, some specialized, used in the installation. This task is not the trickiest electrical installation, but you might want to think twice about DIY, here, when an electrician using good tools can do it in 1/2 your time, cleaner, and probably for not much more money, once you count tool acquisition and runs to the hardware store for something you didn’t remember or know you needed.

See also:

• Wiring Simplified is an outstanding book for both veteran electrical installers and new homeowners looking to save a bit by tackling easier projects, including the installation of receptacles in existing and new locations in all manner of finish surface materials. I got my copy at Home Depot ten years ago and I’m still using techniques learned from it.

200A Service Upgrade and new receptacles

This project on S Melville St. features:

200A Service Upgrade and new receptacles

• 200A service upgrade and new receptacles from existing 100A, with 30+ breaker positions and GFCI receptacle at panel location in garage.
• Add 4 receptacle outlets, including a GFCI for the 2nd floor bathroom.
• Convert (3) 220V receptacles to (3) 120V receptacles on dedicated AFCI breakers.

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 >>

Victorian twin whole-house rewire

I coordinated closely with General Contractor (GC) Jaysun Taylor for this bank-financed project to provide all modern wiring and 2008 NEC code-compliant locations and new protection technology (AFCI, GFCI) for the entire property.

Read more >>

Basement bath renovations electrical

The scope of this electrical contract for bath renovations in a tight basement area was to provide all new point to point wiring and devices/fixtures. Also, to delete a pair of wall outlet locations, move one to coordinate with the new vanity cabinet location and enclosed shower stall, add a new ceiling fixture location and expand switching controls to provide for separate controls on each lighting point, the exhaust fan, and newly-added ceiling heater.

The NEC-required GFCI receptacle at the vanity features GFCI protection from a remote device in the utility room behind the shower enclosure (glass walls not yet installed), avoiding unnecessary button clutter on the devices located in this finished area.

3-gang lighting and fan controls includes a logic-controlled fan timer to conserve energy.

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. The LED performs particularly well in this application, where the luminaire uses its focused downward beam to the maximum, the diffuser adds a bit of warmth to the otherwise slightly cool 3000K color temperature, and the difficult lamp-change procedure behind a gasketed damp location recess trim could be a nuisance using shorter-life lamps (even CFL's have a rated life less than half as long).

Robert Monk Electric delivered the electrical installation as quoted during coordination on a tight schedule with other trades. A $50 additional charge applied to relocate the heater timer from beside the entrance doorway to beside the vanity GFCI (requested during construction), and the customer approved a $10 charge (cost) for the upgrade to LED lamp for the recessed damp location ceiling light.

See also:

• Utilitech Pro 7.5W LED A19 Lamp Review
• Utilitech Pro 7.5W LED A19 Lamp at Lowe’s
• Lighting controls products

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 >>

Recessed lighting upgrade via attic crawlspace

Recessed lighting upgrade via attic crawlspace

This was a tidy little project to upgrade aged and cheap track fixture ceiling lights in two rooms, into separately switched new recessed lighting points at new locations, and install fan-support rated fixture attachment point for the customer at the feed location of the deleted track fixtures. The biggest challenge was to minimize plaster damage while installing new wiring enclosures on old wires, and adding a ‘gang’ to switch boxes to accommodate a second switch for each room. Solution: do the recessed lighting upgrade via attic crawlspace!

The pictures tell the story: success at the ceiling recessed light locations and a blemish or two at the switch locations. Some of the marginal plaster repair needed was original to the previous installation, which had been covered by clumsy, ‘jumbo’-sized wall plates that I was unable to duplicate out of truck inventory.

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 >>