Solar PV in/out dual meters and 200A upgrade

An existing 100A underground service with standard meter and timer-interrupted OP meter (OP tariff no longer available)

Mandolin and I have spent a couple beautiful days this week upgrading an underground service from 100A to 200A, and re-configuring the metering to support the net output of an upcoming solar PV installation by frequent partner and friends,  Sumintra, LLC.

PECO requires two meters for grid-tied solar PV installations: 1 to measure what they deliver, and the 2nd to measure what you provide to the grid. The difference is what you pay, and PECO settles up any overpayment at the end of each year.

Since I could not make the underground service RMC raceway (‘conduit’) and service entrance raceway connect directly to any arrangement of right- or left-hand meter enclosures, I had to install a wiring trough between the existing pipe work and the new meter configuration. As it turned out, the short conductors of the original installation required a splice box in any case, since they would never have stretched across the generous wiring space of a 200A underground meter enclosure.

Using the trough also allowed me to shift the new meter setup to the right of its previous location, providing proper safe working clearance for this equipment.

Bad ceiling fan by Hampton Bay, 122-135 “Hawkins”

This higher style fan was priced such that it ought to have come with a drop tube mount option. The mounting bracket relies on “two screws and washers provided with outlet box”, but few fan-rated boxes include such hardware.

The fan housing/canopy requires perfect ceiling and excessive force to twist into place.

New post lamp: outdoor weather equals time for exterior lighting

The season of garden parties and BBQ’s has arrived, and it’s time to adjust (or upgrade to auto-adjusting) lighting timers and controls, or even upgrade exterior lighting. For example, this project to supplement an existing timer-controlled lighting circuit with a new post-lamp for pathway lighting:

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.

Fun with four-gangs

Four-gang switch boxes can get complicated. In this box, two circuits enter, one leaves unswitched. The remaining circuit feeds one socket of a duplex receptacle directly, and the other socket via a switch loop through a remote humidistat switch. An intermatic EI600 switches the same source circuit, sending switched phase through kill switches: one to alley lights and one to a front yard post lamp.

Wire the grounds together first, as they will connect regardless of which circuit they may associate with. Next wire the neutral conductors together, taking care to keep neutrals of different circuits separate (GFCI and AFCI circuits will not tolerate mixed neutrals, since they will cause imbalanced return current through the protective device). Next connect the fixture phase wires to the switch controlling them. Finally, connect the proper source circuit phase wire to each switch (by this time, the number of loose wires should be very manageable).

Lots of tools for a little baseboard outlet

Maestro® Occupancy Sensing Switch — GFCI incompatible

I had a mixed experience installing the new-ish Maestro occupancy sensor switch. It uses a ground connection — to equipment ground — to power low-power electronics in the sensor. This makes installations in old wiring applications straightforward, but complicates new work installations, since the most common areas for an occupancy sensor will be kitchenettes, bathrooms, laundry areas and utility rooms that all may have plumbing or other features requiring GFCI protection.

Occupancy sensors mounted with GFCI — but not protected by the GFCI function!

The use of equipment ground for a current path to power the sensor electronics means that the sensor may not be installed on GFCI circuits designed to prevent shock and electrocution hazard from precisely this type of current path. The GFCI sees the unbalanced current to ground via the equipment grounding path as a ground fault. I have not tested the sensor on AFCI circuits, which also include ground fault detection, albeit at a higher threshold (more current before trip).

Read more about Occupancy sensors, filament and non-filament lamps and GFCI protection

Shout out to Radio Shack on 59 W Chelten in Germantown

Kudos to Radio Shack for being in the neighborhood, being open, and still stocking a few basic electronics items, like what I needed: a 25V / 120V AC step-down transformer for boiler repair.

I knew what I wanted. They were open at 7:20pm, in the neighborhood. The display for my item was easy to find, clear and well stocked. Service wasn’t go-out-of-your-way smiley and helpful, but I’m just happy they were there when I needed them.

I hope Radio Shack will never allow consumer-electronics in shiny bling packaging to fully eclipse what use to be their stock-in-trade: professional and hobby electronics parts and educational kits.

Den recessed lighting accents fireplace mantle

This small project brought four new recessed lighting locations to a 2nd floor den, nicely highlighting the fireplace mantle there.

Recessed lighting is ideal for perimeter accent lighting, as at this fireplace mantle.

Rewire of antique drawing room plaster medallion chandelier pendant

Sometimes, rewiring one part of a home provides an opportunity to take care of something really special. While re-wiring the third floor of a 1860′s classical twin in West Philly / University City (an insulating company would not work until knob-and-tube was removed from the attic), I got the chance to fish across 25′ of high plaster ceiling above a gorgeous drawing room, to bring modern cable wiring (NM-B aka “Romex”) to a ceiling pendant chandelier installed in the middle of a 2-foot decorative plaster medallion.

Getting the cable to the location was only half the battle. The original fixture was gas light. The existing electrical replacement used the abandoned gas pipe for mechanical support, but the support system, typically for first-generation electrical fixture locations throughout West Philly, did not accommodate a proper wiring enclosure for junctioning fixture leads to the house wiring system.

I was able to adapt 1/2″ pipe to the 3/8″ gas pipe to coordinate with the 1/2″ knockout of standard wiring enclosures. I used new pipe lengths sized to get the new box flush to the plaster medallion, after carving a new recess pocket for the enclosure using a 4″ hole saw. This location now enjoys superior mechanical support, modern, grounded electrical wiring with both circuit conductors grouped close to minimize EMF radiation, and overall better interface between the fixture’s decorative canopy and the original decorative ceiling oval plaster medallion.

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.

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

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 >>

Who needs ground wires? Modern cables don’t mean proper wiring

I recently extended an existing circuit that looked great on initial inspection, but turned out to consist of multiple basement junctions where the equipment grounding conductor in the modern type NM cable had been cut short and left hanging un-terminated.

In a lightning storm, the magnetic fields induced by nearby high-voltage lightning strikes will induce current in anything metal in the home, including wires. When grounding conductors are bonded properly to provide a low-impedance path to ground at the service equipment, they can help to quickly drain away transient voltage surge before it can find an unintentional path to ground that may cause damage. Similarly, the same low-impedance ground fault path ensures that short-circuit current through circuit breakers will be maximized, helping them to trip quickly and protect equipment, buildings, and people. 

More lazy ground wire twist photos and notes >>