Friday, November 21, 2014

Winter Heating: Humidity and Apparent Temperature

Having problems getting and staying warm this winter? Finding yourself pushing the thermostat up past your usual comfort range?

The problem might be related to low relative humidity. The colder the outdoor temperature, the more heat must be added indoors for body comfort. However, the heat that is added will cause a drying effect and lower the indoor relative humidity, unless an indoor moisture source is present.

As an example, a comfort level of 70°F at 50% RH feels more like 65°F at 20% RH, a very typical humidity for a home without humidification.

Apparent Temperature for Values of Room Temperature and Relative Humidity
Many central heating systems incorporate automatic humidity controls; however there are often non-functioning or in need of service. Alternately, you can purchase a warm-mist or cool-mist humidifier.

Finally, there are solid (and cost-effective / green) tips to be found here: 6 Ways to Humidify Your House (Without a Humidifier)

See also: 

Sunday, November 2, 2014

Standard Time and Resetting the Clocks

Daylight Savings Time ended this morning at 2:00 am. and like most of us, I've spent the morning checking, and resetting as needed, the household clocks and devices with timers.

Some things auto-reset:
  • Windows based PC and laptop
  • iPad
  • iPhone
  • Roku video player
Some "clocks" had to be manually reset:
  • Bedroom alarm clock (digital)
  • Yoga room clock (digital)
  • Car stereo clock
  • Television clock 
  • Analog living room clock
  • Kitchen clock (one of those Sieko "catch the GPS wave" clocks that never seems to be right)
I rarely if ever wear a watch, so if there are a few hanging out, it's a coin toss whether it's set to standard time or daylight savings time, depending upon when I last wore it. 

Clocks associated with energy savings and monitoring:
  • Digital thermostats (four devices) 
  • Mechanical timer for the basement dehumidifier
  • Front porch timer
  • Efergy power / demand monitor 
Clocks arbitrarily integrated into appliances:
  • Microwave oven
I've gotten lucky on that one, most modern kitchens have a host of clocks - stove/oven, coffee maker, refrigerator, crock pot - but I've got older / lower cost appliances. That being said, I am sure I will come upon some clock in the next few days that has escaped notice.

Most have been pretty easy / intuitive to change, although the front porch timer (integrated into a standard wall switch) is tiny.  Occasionally I'll come across a clock that seems inscrutably resistant to adjustment, but not this time.

Someday, all of these devices will be connected to the internet, and all this stuff will happen automatically. But not today....

Thursday, October 23, 2014

MyLight: Automated Night Lighting

The MyLight: Automated Night Lighting came across my social media transom this afternoon. 
The Mylight collection is a series of innovative LED-light products designed to enhance one´s lifestyle — delivering comfort and safety in your home. The Mylight is motion activated and turns on and off when you need it so no more fumbling for switches at night. It provides a soft indirect light for night time use.
While the individual pieces seem fairly simple and straightforward, it's a nice packaged concept - a couple of strings of warm LED lamps, a motion / light detector, a plug / power supply, and hardware to mount it under a bed or cabinet. Priced reasonably ($32 for a single sensor, $45 for a dual sensor unit, on sale). I'd be happy to put one under my bed - but the video makes me think that a nursery, bathroom or child's room would be even more useful.

Thursday, October 16, 2014

Checking Outlets

An electrical outlet tester is an invaluable tool for any homeowner, do-it-yourself-er, or professional working in the electrical or energy field. There are many different types of devices that all qualify as "outlet testers" - and here we'll review the capabilities (and limitations) of the various devices.

The basic outlet tester (~$5 from home improvement and big box stores) provides a quick check of outlet wiring, and the presence of voltage on an outlet.

It can spot an open ground, open neutral, reversal of hot / neutral, or hot / ground. And it gives a quick "OK" check. Perfect for a quick check of all outlets in a space, checking on a repair, or confirming power at outlets, plug strips, etc.

For a few dollars more (~$10-15) one can get this device with a GFCI test button - pressing the button places a small (~ 20 mA) load between hot and ground. A properly wired and functioning GFCI outlet or circuit breaker should trip. Again, a good "quick check" for GFCI outlets in kitchens, lavatories, exteriors, garages, and other wet locations. It's especially handy if (for instance) a string of outlets is supposedly wired from a single GFCI outlet - one can check each outlet to confirm it's actually fed from the GFCI outlet and wired correctly.

Now, both of these devices are fairly limited in capabilities. They do not place a significant load on the source, so cannot identify loose or corroded connections, nor determine voltage drop for distant outlets. They cannot discriminate between the grounded (neutral / white wire) conductor and the ground (green wire / safety) conductor. Mixing or intermingling neutral and ground connections can cause electrical noise, safety concerns, and magnetic fields.

More advanced outlet testers are available to provide more thorough inspection and analysis of electrical outlets.

The first feature is the addition of an electrical load to provide some indication of voltage drop. Typically measured in percent based on rated load - the National Electrical Code suggests that "5% voltage drop under rated load" is "adequate for good service". Voltage drops exceeding 10% are possible - depending upon conductor size, run length, and condition of connections / junctions. If one is (for instance) using such an outlet for a home office in the far end of the building, with a laser jet printer, space heater, or mini-fridge, light flicker, low voltage, transients, and other problems may ensue.

A quick survey of outlet testers that measure voltage drop include:
  • Suretest (Ideal Industries) - Various models, $300 - $400
  • Extech Instruments - CT70 / CT80 AC Circuit Analyzer, $150 - $250
  • Amprobe - INSP-3 Wiring Inspector Circuit Tester, $300 - $400
  • General Specialty Tools & Instruments - CA10-AC Circuit Analyzer, $100 (great value, especially as it's advertised to measure neutral and ground conductor impedance!)
These devices incorporate a variety of options and features (digital metering, testing of neutral and ground impedance, PC interface, etc.) 

As a power quality consultant, I carry a small outlet tester with me to any site that might involve 120 VAC AC power issues. Such a device permits a rapid survey of all receptacles in an area or space, often spotlighting the problem area quickly - my report includes a table of all outlets tested, eliminating the need to open up each and every outlet, and allowing me to focus on specific problems.

In addition, grounding issues (especially intermingling of neutral and ground wires) can cause ground loops, ground noise, and magnetic fields. So if I'm looking for noise issues on a higher voltage or dedicated electrical system, checking out all of the nearby AC outlets is a good way to be sure there's no sneak path for ground currents or noise.

Tuesday, October 7, 2014

Nobel Prize in Physics - Blue LEDs

The Nobel Prize in physics goes to three men who gave us blue light-emitting diodes, used daily in your smartphone screen - Washington Post / Oct 7, 2014

A little "Residential Power and Energy" shout-out to these gentlemen - Isamu Akasaki, Hiroshi Amano and Shuji Nakamura. When I was cutting my engineering teeth, there were red LEDs, amber LEDs, and green LEDs. But without blue LED's, it's impossible to make white light (red + green + blue) and as a result, low energy LEDs were not useful for things like video images or illumination. They were used quite early for traffic lights (red, amber, green - works out!)

Now, "white light" LEDs, based on this discovery, permeate our world. My smartphone, low power flashlights and lanterns, low power residential lighting. I'm pretty sure there is not a single room in my home that does not use these in some way.
Red, blue, and green light combine to make the bright white produced by LED lightbulbs. Bulbs using blue light-emitting diodes are more efficient and have a longer lifetime than old fashioned bulbs (up to 100,000 hours, compared to 1,000 for incandescent bulbs and 10,000 hours for fluorescent lights).
Wonderful to have something so practical, and uniquitous, recognized by the Nobel Committee.

Wednesday, October 1, 2014

Efergy E2 Classic Energy Monitor

I recently picked up a small energy monitor for my home / condo, made by Efergy Technologies Limited. I'm always looking at new / low cost ways to monitor, measure, quantify electricity and power. The price point here was minimal ($100). The functions and feature set (monitoring demand, wireless display that can be moved throughout the home, USB interface to access data and produce reports, software to facilitate all that) all looked great.

Here's a quick review.
Technical Capabilities

Strictly speaking, the device is a CURRENT monitor. There are two clamp on current probes, but no voltage connection point - it calculates demand based on a fixed voltage, and presumably a unity power factor. I have not determined it it measures average current or true RMS at this point. It samples data on a 10 / 15 / 20 second rate. It's not super accurate, as a result, but it's "close enough" and certainly can provide a good comparative measure of energy usage over time.

It also has a third current probe "port" so can presumably monitor three phase power as well. It appears to be designed for a world market: 50/60 Hz, multiple nominal voltage settings, and multiple rate / tariff units.


The monitor was easy to install. Two clamp-on current probes (A) were connected to the mains coming in. I have a 100A panel, the probes appear to be sized for 200A maximum. The probes are not spring loaded, but use a nice little plastic latch / clip for secure connection, and since there is no voltage monitored, the vector / direction of the probe does not matter. I'm comfortable sticking my fingers in a live panel, but to be safe, kill the power before installation.

These are connected via a fixed cable to a transmitter (B) which is powered via 3 x AA batteries, or an optional DC supply. The company claims battery life of 8-10 months is typical for both transmitter and monitor.

The wireless display / monitoring unit (C) can be located anywhere convenient; I placed it atop the panel for the photo. It's powered via 3 x AAA batteries. The transmitter / monitor are linked via a simple push-button procedure. I had no problems getting them to talk. The expected range is 100 - 200 ft. although I found signal was sketchy up on the second floor. 

The past week I've had the wireless display sitting on my desk as I've worked, and have enjoyed (yeah, I'm an engineer, what do you want) watching the kW measurement track up and down as I work throughout the day. 

Monitor / Display Unit

The display for this device has some rudimentary information. There are three values available:
  • Energy Now (KW) 
  • Cost (per day) based on present energy ($)
  • CO2 (per day) based on present energy (KgCO2) 
In addition, the device displays all of these parameters as an Average (over the life of monitoring, with energy in KWHr) and History (scroll through a daily, weekly, or monthly tally of demand, cost, and CO2)

The device allows you to set up variable rate (single or multiple) in cost / kWHr, and a CO2 usage factor.

The display is pretty rudimentary; and if I were relying on that I'd probably check out the Efergy Elite True Power Meter (more sophisticated measurement, more advanced display, temp & humidity) but that  device does not have "in the box" communications capability to a PC, and I am all about the data.


The free to download software, elink, is pretty spiffy.  The basic HISTORY function displays demand on an hourly basis (per day), a daily basic (per month), or a monthly basis (per year)

Under the MANAGE function, the user can look at individual days, do a weekly comparison (for instance compare individual weekdays or weekday vs. weekend), as well as a month by month comparison.

Finally, there are some advanced options of tracking actual usage vs. planned usage, setting up complex utility tariff schedules (for those working with peak / off-peak billing) and adding multiple utilities (so one could presumably compare different rate schedules with actual historical demand data)


Last but not least, the software gives the option of generating a Daily or Monthly report - selecting a specific time period, and creating a PDF report. The "Add Stickie"feature is not all that intuitive or well documented, but from the main HISTORY page you can create comments on notable usage or patterns which would be great if one were creating a report for users, management, clients, etc.

The exported spreadsheet is pretty rudimentary: Date / Time / KWHr / Daily Max / Cost / Stickie Note(s). Including the Stickies is a nice touch. But really, the PDF report is pretty much all I might need.  

Using the Efergy Demand Meter

I can think of a lot of ways to use this device.

Professionally, it would make a great tool to do short and simple residential / small business demand audits. Hook it up, perhaps do some walking around turning things on and off and recording the demand, then leave it connected for a week and generate a report, with recommendations for savings.

As an end-user, I'd probably first characterize the household energy consumers. I'll be able to (over time) generate the cost (in electricity) for things like a load of laundry, a shower, a hot bath, and factor those in a bit. Might even consider replacing older / less efficient appliances. And although I've gone through the condo pretty well in terms of replacing incandescent bulbs and other energy hogs, perhaps I'll find something I've missed - most consumers who have been less fanatic than I will probably find a lot of room for improvement.

I can also watch the electrical demand on a real time basis, and if I've left something on (stove burner, iron, etc.) I should be able to spot that quickly.

Bottom line, really nice piece of technology - really well designed (hardware and software) and useful.

Tuesday, September 30, 2014

Thermal Imaging for the Homeowner

I've had an infrared thermometer in my tool bag for many years. These devices, small point and shoot meters often with a laser "sight" to ensure proper aiming, do a great job of measuring temperature of terminals, conductors, circuit breakers, transformer cores, etc. and I can be very useful for troubleshooting or diagnosing electrical problems.

Once a significant investment ($100-$200), prices have dropped considerably. This one, the General Tools IRT207, is under $40 from Lowes or Sears;  you can find low end devices for under $20 from some outlets.

Pricier "thermal imaging cameras" are a more recent innovation, which take still photos or video of infrared emissions. Running $2000 and up, these are out of range of most home-owners and small commercial users; but have become mainstays of home inspectors, electrical contracting, energy engineers, etc. And while prices have dropped (and features and capabilities have risen) these devices are still out of reach for most consumers.

But recently, several devices have become available in a much lower price range. While I am sure there are competitive units out there, I'm going to spotlight two different devices from Flir Systems.

First, the FLIR TG165 Imaging IR Thermometer  is a neat cross-over device; an infrared thermometer with a small (80x60 px) video image. The video is a little gung-ho for my taste, with driving rock music and Monster Truck Rally voice-over such as:
  • "...not your old-school spot radiometer..."
  • " images and data, and whip up a report later..."

Nevertheless, it seems like a great little device, and at ~$500 retail, it's dropped into the affordable range for many.

Next, and more exciting (to me) is the Flir One: Thermal imaging device for your iPhone 5/5s. This is a case for the iPhone device that includes a thermal / infrared imaging device. At $350 it's even more affordable than the handheld device, has a bigger image size, although perhaps less "point and shoot" ability (laser sight, etc.)

The applications of these types of devices are pretty broad for the creative home-owner, business owner or hobbyist, but some of the things I've stumbled across over the years include:
  • Electrical inspection
  • Mechanical inspection (fans and motors, automotive belts, pulleys, etc.)
  • Energy conservation (checking insulation, windows, doors, ducts, walls, roofs, etc.)
  • Checking for insects / pests / vermin in walls (apparently they produce a thermal signature)
  • Checking  plumbing fixtures.
  • Checking / calibrating cooktops and overs
  • Seeing in the dark (security)

Saturday, September 27, 2014

How to Save Money and Energy Despite Having Electric Baseboard Heat

When I purchased my most recent home, one of my big concerns was the heating system - specifically, electric baseboard heat. I've been living with gas heat for years - hot water baseboard, forced air in Hartford. I was concerned about comfort, of course, but mostly I'd heard much about the high cost of electric heat.

Now there are many innovative adaptive heat controls out there (the Nest device is particularly interesting, and worth it's own blog post at some point) - but for the most part these low voltage controllers are not designed to work with line level voltage used by electric baseboard heat.

Savings Opportunity #1: Zoned Heat

Balancing the cost of electricity, electric heat brings one big benefit - it's inherently zoned. Which means, instead of one thermostat for the whole residence, or perhaps two (upstairs / downstairs), most electric baseboard heaters have independent heat controls, called thermostats. My space (a small condo) for instance, has seven thermostats: living room, kitchen, master bedroom, spare bedroom, two bathrooms, and the basement. So there is a lot of possibility for fine tuning the heat - to heat just the spaces I commonly use, and perhaps save some money.

Savings opportunities include turning down the heat, and closing off unused or little used spaces, and  turning heat down in the bedrooms during the day, and other living spaces at night.

Savings Opportunity #2: Install Digital Thermostats

When I moved in, all of the thermostats in the place were old-school electro-mechanical devices. There was no visible temperature reading or feedback, the rotary dial was exceptionally coarse (with a resolution of 10ºF) , the calibration was highly suspect, and the heat control was simply ON / OFF. If the temperature dropped below a set point, the device turned on 100%, the space heated, and the device eventually turned off.

Such a system is prone to "heat creep" - with the resident feeling a little cold and turning up the heat without a lot of thought to what the actual temperature is (and then acclimating to the higher temperature), and without a good reference to turn heat up or down consistently.

So the first step in saving money is to install a Digital Thermostat. Such devices are available at home improvement stores for about $25 each. Make sure you purchase thermostats intended for line voltage (120/240 VAC) as opposed to low voltage devices intended for oil / gas furnaces.

An aphorism I picked up in the corporate quality world was "If you measure something, it gets better" and the digital thermostats have a thermometer on them providing immediate feedback to the resident. So instead of simply "feeling cold", the resident can look and see the actual temperature. It's amazing how much things like health / energy / activity, as well as the ambient humidity and outdoor light level, affects a person's perception of temperature. So with a digital thermostat, the resident can now see that the room temp is 65ºF (or whatever the comfort level is) and put on a sweater or sweatshirt rather than nudge it up a bit.

In addition, the digital thermostats have a much finer resolution (1ºF) which means even if the resident decides to warm it up a bit, s/he can restrict that to a few degrees. Finally, the digital thermostats use proportionate triac controls - which means that the heat is not simply ON / OFF, but might have four settings: ON / LOW / MEDIUM / HIGH. As the temperature drops, the heat turns on LOW - and if that's enough to warm the space, it never gets past that. So the heat control is more subtle / even and therefore more comfortable.

The electrical installation is fairly simple - comparable to changing a light switch. The only complexity is that the older thermostats are DPST (Double Pole, Single Throw) - which is to say they break both lines (in many cases, the baseboard uses 240 VAC with two hot lines). The digital device is SPST (Single Pole, Single Throw) - so one of the baseboard lines needs to be connected directly.

Savings Opportunity #3: Install Programmable Thermostats

Now, simply adding digital thermostats still leaves a lot of room for energy waste - if the resident neglects or forgets to turn the thermostats down at night or during unoccupied periods. In addition, turning the thermostats down at night means waking to a cold home. the next step is to add programmable thermostats to key areas: the living room, the master bedroom, the basement. This device is a bit more expensive: $50 at home improvement stores.

It has the same general functions as the digital thermostat, but adds a programmable function. The device shown in the photo permits four different timed settings per day (typically WAKE / LEAVE / RETURN / SLEEP) and can be programmed differently for weekdays (Mon-Fri) and weekends (Sat-Sun).

An example of heat programming: 
  • Drop the house down to 58ºF at night; some folks like a cool house to sleep
  • Prior to normal wake-up time, heat the house up to 65ºF or a comfortable temperature. 
  • During the day, drop things down to 62ºF (if at work or out of the house). 
  • Increase heat to 65ºF in the late afternoon for the remainder of the evening. 
One of the benefits of a programmable thermostat is that if the resident wants it a little warmer, or happen to be hanging in the living spaces during the day, they can bump the thermostat up confident that it will reset at the next timed change, and not leave the house warm indefinitely.

One downside of programmable thermostats is the need to program the thermostats and maintain the clocks (daylight savings time). The Wikipedia article cited above in fact notes: 
Difficulty with usability in residential environments appears to lead to lack of persistence of energy savings in homes...In addition to potential increased energy consumption, digital programmable thermostats have been criticised for their poor usability. 
But if one is committed to energy (and cost) savings and thoughtful about programming these devices, they can provide real savings. Hopefully, in the future, "smart devices" (such as the Nest device designed for low voltage systems)  that communicate and self adapt to resident patterns and habits will eliminate the need to manually program devices in the future.

Additional Savings: Cleaning Electric Baseboards, Positioning Furniture

In addition to thermostat upgrades, cleaning baseboards periodically will help to improve airflow - even a thin layer of dust will impede the convection flow such devices rely on. In addition, keeping space in front of such devices will prevent hot spots and permit even heating - consider using bricks or pieces of wood to space furniture away from heating units and permit greater air flow.

Wrapping an Electrical Power Cable

This one is a little obscure - but a great place to start. Anyone working with electrical power should learn the best way to wrap a power cord or cable - called the Over / Under Wrapping Method. Whether you use your electrical cords for outdoor equipment, holiday lighting, or home improvement, wrapping a cable properly can save time when it comes to use the cable, and add years to the cable or cord life.

If you want to get away from the coiled cable look (even after you've unwrapped your cable!), and you want to be able to unwrap your cables fast, and want your cables to store without added tension (just say NO to the carpenter's elbow wrap!), then try the following method. It's a little difficult to explain, and may take some practice, but once you have it down you can wrap cables faster AND better than ever before - by the way, this is the method most professional roadies use. 

Proper Cable Wrapping /

A few comments about this video:

First, "...they'll just wrap it up like it's an electrical cord...". In reality, electrical cords get just as tangled, twisted, and damaged as video and audio cables without proper wrapping and stowing.

Second, the demonstration here is fine for smaller cables (audio or video), and shorter lengths. But for longer and/or larger cables, you will probably need to make a larger diameter loop, and rather than pulling back an arm's length (as shown) take a full two wingspan across the body and two arms. The over / under technique still works.

I learned this skill working in the video production field. I always assumed it had naval origins (seems to be the best way to wrap a line for quick and twist-free deployment, and sure enough, it's known as faking a line in those circles) But you can learn it as well.

New Beginnings

My name is Jude. I'm a long time blogger (since 2001) and a longer time electrical engineer (since 1983). I've been working in the field of electrical power quality for my entire career. And while I mostly work with higher power systems (480 VAC / 3 Phase / 200 KVA and up), I've done my share of work with lower power systems for offices, smaller facilities, and residences.

I've decided to start a blog focusing on electrical power and energy for residential and small commercial users - relying on half a lifetime of work in this field, and consolidating, integrating and updating documents, posts, and other material I've written and/or published over the past 30 years.

While the focus and scope of this site will, by its nature, evolve and change over time, I'm hoping to cast a wide net to bring in a variety of subjects of interest:
  • Electrical basics
  • Measuring equipment
  • Energy savings
  • Electrical power quality
  • Lighting
  • Green power
  • Back-up power systems
  • Vehicle power interface
  • Renewable power
I'll be spotlighting companies, products, residences, and industry trends.

Your participation and comments are welcomed - I'm happy to entertain suggestions for topics, products, or issues!