Demystifying the mystifying GFCI

2013-07-30 by tester101. 3 comments

A commonly misunderstood electrical device, is the Ground-Fault Circuit Interrupter (GFCI).  Whether posing as a circuit breaker, or a receptacle, the GFCI device is almost always misunderstood. To understand the GFCI, however, you have to know a bit (and I mean a really little bit) about transformers.

This is a transformer.


(Well, a crude representation of one anyway).  It consists of an iron core, and a couple coils of wires.

Transformer Coils

More specifically, it has a primary coil of wire, and a secondary coil of wire.

Transformer Labeled Coils

When you place a voltage on the primary coil, some magnetic magic happens in the core and a voltage is induced on the secondary coil.

Transformer Working

And there you have the most basic crash course, on the most coarse basics of transformers. Which is all you need, to understand how GFCI devices work.

Inside a GFCI device, you’ll find what’s called a Current Transformer (CT).  A crude representation of a CT, looks something like this.


A CT works just like any other transformer. When a voltage is applied to the primary, a voltage is induced on the secondary. The only difference, is that the primary isn’t a coil, exactly.  The primary is instead the ungrounded (hot), and grounded (neutral) conductors of an electrical circuit.


When current is drawn on the circuit, it flows down the ungrounded (hot) cunductor. Out to the consuming device, then returns back to the source on the grounded (neutral) conductor. Similarly, if we draw current from a GFCI device.  It flows down through the ungrounded (hot) conductor, and through the CT core.

CT in GFCI  (Current on hot)

The current then flows back through the CT on the grounded (neutral) conductor, and back to the source.

CT in GFCI  (Current on Both)

According to the right hand rule. If you point the thumb of your right hand  in the direction of current flow, and wrap your fingers around the conductor, your fingers point in the direction of the magnetic field produced by the flowing current.  If this is done with the above diagram, we end up with magnetic field lines like this.

CT in GFCI  (Current on Both with Magnetic feild lines)

Because of the proximity, and opposite-ness of the fields. They cancel each other out, and no voltage is induced on the secondary coil of the CT.

CT in GFCI  (Current on Both with Magnetic feild lines) Even

In the case of a ground-fault, however, not all the current will flow back along the grounded (neutral) conductor. This creates an imbalance in the magnetic fields, which allows magnetic magic to occur in the transformer core, and a voltage is induced on the secondary of the CT.  If the voltage on the CT is large enough, and lasts long enough, the GFCI device will open the circuit.

CT in GFCI  (Current on Both with Magnetic feild lines) Not Even

Next time you come across a GFCI device that continually trips, think about how it works and what it’s looking for.  This might give you a better idea of what to look for, and where to start troubleshooting. And remember to always work safely, and cautiously whenever you’re working with electricity.

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Ground Fault Current Interrupters

2012-03-27 by lqlarry. 2 comments

Ground Fault Circuit Interrupters (GFCI) have been part of the NEC code for over 40 years now and just like your car, things have changed. Over the years the code has changed but also makers of GFCI and Underwriters Laboratories (UL) have made a lot of good changes. Life saving changes that probably nobody except a few electricians have noticed. Today, most people just think of the GFCI in their bathroom or kitchen and will probably never know all the great GFCI that are available.

Today, the sGround Fault Circuit Interruptertandard GFCI that you see in your wall is either 15 or 20 amp and the most noticeable feature you see is a light, usually a little green light. If you don’t see the light or the light has changed colors then your GFCI will not work. What you don’t see is that GFCI are self testing every 15 minutes. A trip can be reset, but a failed GFCI will not reset and you will have to replace the GFCI. Another feature is that the GFCI comes from the factory in the tripped position and if it is mis-wired you will not be able to reset the GFCI until it is corrected.

Tamper Resistant GFCIDid you know there are tamper resistant receptacles and GFCI? Now manufacturers make tamper resistant GFCI for your children’s bathroom. These meet the same stringent requirements of a standard GFCI, but now somebody cannot just stick something conductive into any slot of the GFCI. Now you can sleep better at night knowing your kids are safer. The tamper-resistant receptacles and GFCI have been NEC code since 2008 but not all municipalities are enforcing it yet.

Now you can buy weather resistant GFCI. It will still have to go in a weather resistant cover or even a bubble cover. Weather-resistant GFCI are made to go outside, being able to take extreme temperatures, UV and moisture. The weather resistant GFCI are also made with the tamper resistant feature.

FacelesFaceless High Current GFCIs GFCI are also made. This is just GFCI made with only the test and reset buttons, no receptacle built in, like it’s name implies.

Another faceless GFCI is the high current GFCI which can handle up to 80 amps at 240 volts. These feature a current sense transformer called a donut which is powered by 120 volts. If you need a GFCI for your spa or equipment and cannot find a breaker, then these will come in handy. The high current GFCI should only be installed by a licensed electrician.

Do you need a night light or a guide light? GFCI are made with a receptacle and a light. A photo sensor turns the light on and off. How about a pilot light with your GFCI? The light comes on when there is a load on the GFCI. Comes in handy in basements with sump pumps. All the lights are LED for low power consumption and long life.  Do you need a switch and the only room is a GFCI? Replace the GFCI with a combination switch and GFCI. The switch is independent of the GFCI and can turn on that vent or light. These combination devices can also be purchased with the tamper-resistant feature and no safety feature has been removed.

There are other GFCI made like extension cords with GFCI, or GFCI that can be wired in as the plug of an extension cord.  Panel mount GFCI are available for sump pumps, generators or temporary power.

Assorted GFCI

Night Light GFCI, Pilot Light GFCI, another Night Light, Switch Combo, and Cord GFCI

While this might not have been the most exciting read you’ve had today, I hope that this might help on your next DIY Home Improvement Project.

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Arc Fault Breakers

2012-03-06 by lqlarry. 3 comments

Arc Fault Circuit Interrupter Breaker

Before we get into Arc Fault Circuit Interrupters (AFCI), let’s look at their uncle, the Ground Fault Circuit Interrupter (GFCI). GFCIs first appeared in the NEC code in 1971, and then only for swimming pools (not spas) and exterior outlets. Today, bathrooms, kitchens, wet bars, garages, rooftops, spas and any place that water can be a problem must be protected by a GFCI according to code. Without getting into what a GFCI does, it basically can save your life. This has been proved over and over, and unfortunately also proved when GFCIs have been removed, tampered with, or failed.

Let’s start off with some questions:

What is an Arc Fault? An arc fault is when current goes through your wires and somehow takes an unintended course that produces a spark, or arc.

Why don’t my regular breakers protect me from arcs? Your breakers protect you, but what an AFCI does, that a regular breaker can’t, is detect a very low level arc. If not detected, that low level arc could quickly become a life threatening event – in your house!

Why do I need AFCIs and GFCIs? A GFCI protects you and others from fatal electric shocks when a ground fault happens, like if you try to make toast while taking a bath and drop the toaster. That would be a ground fault due to water. As explained above, an AFCI protects you and your valuables from a potential fire caused by a low level arc.

What causes arc faults? Worn or damaged wire; damaged plugs or receptacles; loose electrical connections; screws, nails or staples driven into wires; furniture pinching lamp or appliance cords; broken wire; frayed wires; and even wire chewed on by your pets. Probably anything your kids do when you’re not around. The NEC uses the term combination to describe fault protection. This covers both parallel arcs (two wires arcing together) and series arcs (arc caused by one wire arcing between two damaged areas)

Can I buy AFCI receptacles? Not at this time. Breakers will protect everything downstream from the breaker, but an AFCI receptacle would not protect the wire between the receptacle and the breaker.

Cause and Effects of Arc Faults

Cause and Effects of Arc Faults

Whether you need AFCIs or not depends on your local codes. Not all local codes have accepted AFCIs as code, and some might accept them but not otherwise be up to the current national code. The current NEC Code, 210.12 says All 120-volt, single phase, 15- and 20-ampere branch circuits supplying outlets installed in dwelling unit family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sun-rooms, recreation rooms, closets, hallways, or similar rooms or areas shall be protected by a listed arc-fault circuit interrupter, combination-type, installed to provide protection of the branch circuit.”  Even if your local code does not call for it, you still can install AFCIs in your home. Of course, if local code requires AFCIs then they will have to be installed on new homes and remodels.

AFCIs keep improving, just like GFCIs. With these improvements, specifications change and an older AFCI might not pass on a new job, depending on when the permits were issued.  Just because a breaker says AFCI on it, that does not mean it will pass inspection. Your electrician will know which ones to use and your local code office will also have that information.


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Tool Review: Ideal Lil’ Ripper Stripper™

2012-02-28 by tester101. 2 comments

I recently picked up the Lil’ Ripper Stripper™ from Ideal Industries, at Home Depot for about $5.00.

Lil' Ripper Stripper

Not that I needed a new tool, especially another wire stripper; but for $5.00, how could I resist?

Really, I was just interested to see how useful it actually was.   I’m almost always skeptical of multi-tools, since they aim to replace tools designed specifically for a single task.  The Lil’ Ripper Stripper is no exception, so it really has to preform well to replace tools in my tool pouch.


  • Rips Romex® wire outer jacket cleanly and quickly.
  • Clips outer sheathing to remove excess Romex® wire jacket.
  • Strips inner conduit wires.
  • Looping holes loop wire for screw-on connections.
  • Twist-Assist™ tightens most popular sizes of winged twist-on wire connectors.
  • Injection molded elastomer grip provides a comfortable, slip resistant grip.
  • Strip length measuring scale allows for quick and easy measurements.
  • Conveniently fits in your pocket.

Since Ideal gave me a good feature list, lets tackle each one individually.

Ripping Romex® (NM wire)

The Lil’ Ripper Stripper, makes ripping non-metallic cable sheath simple and fast. If you look in one end of the tool, you’ll notice a small metal hook.

To rip the cable, simply place the hook under the cable sheathing, then slide the tool along the cable.  The Lil’ Ripper Stripper definitely earns this part of its name, this thing rips cable like a champ.  It slices through the sheath clean, fast, and without any concern of nicking the conductors.  Because of its shape and size, you can even easily rip the sheath from cables already installed in boxes.

Removing excess sheathing

To remove the excess sheathing, you slide the sheathing into the large notch, at the end of the tool, and pull.

This feature seemed like an afterthought, or maybe the cutting blade was relocated to accommodate another feature.  Either way, it’s not great at this.  The cutting blade is set back a bit too far, which makes getting the excess sheath deep enough to cut it a challenge.   Even the guy in the demo video had trouble with this feature, so it doesn’t seem to be user error on my part.

Stripping conductors

To strip the conductors, you simply slide the wire into the V notch at the end of the tool, give it a couple twists, then pull the insulation off.

It works relatively well, though it can easily nick the conductors if the wire is inserted too forcefully.   You’ll also notice a measuring scale on the face of the tool, which helps you determine how much insulation to remove.

Terminal loops

To create terminal loops in the wire, you insert the wire into one of two holes on the side of the tool, then give it a quarter turn.

This is a nice feature, and works very well.


To twist on wire caps, insert the cap into the end of the tool, insert the wires into the cap, then twist.  This is a handy feature if you’re working in gloves, and find it difficult to twist on little wire caps because of it.  The length and size of the tool give you a little extra grip, allowing you to twist on the wire caps without a problem.  It’s only designed to work with winged wire caps, so if you’re working with caps without wings, you’re out of luck.

Comfortable, slip resistant grip.

The tool is comfortable in your hand, and it does provide a slip resistant coating. However, the best part of the grip is the constant reminder that you shouldn’t be working on live circuits.

DO NOT USE ON LIVE CIRCUITS Not Insulated, misuse may result in injury or death

Conveniently fits in your pocket

Yes, it does fit in your pocket.  But guess what Ideal… I want it to hang from my tool belt! Is it too much to ask for a key chain loop, so I can hang it from a carabiner on my tool pouch? I guess then they’d have to charge $5.50 for the tool, and maybe that’s too steep for the average DIYer.

All in all, this is a fairly nice tool.  It would be a nice addition to any DIYers tool belt, er… pocket. It rips cable sheath really well, strips wires, makes terminal loops, and helps twist on wire caps.  It’s a useful, sturdy tool, but I’m not sure I’m ready to give up my wire strippers just yet.  For a DIYer looking for a useful inexpensive tool, this is a good solid choice.  The Idea Lil’ Ripper Stripper gets 3.5 Captain Constructions, out of 5.

3.5 Captain Constructions


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Fluorescents and Legislation, Part II

2012-02-21 by lqlarry. 1 comments

The death of the Plain Jane fluorescent tube is in the cards. Lighting legislation signed into law in 2007 has been coming at us for 5 years. Fuel economy for vehicles, bio-fuels, lighting fixtures, lamps, appliances and building energy savings were all targeted, along with other items too numerous and way over my head. In 2010, manufacturers were no longer able to manufacture magnetic ballast. These were the coil and core ballast that weighed a ton.   

When suppliers started to run out, your only choice was electronic ballast. You know, if you’re old like me you can remember when those ballasts stuck their heads out in the 70’s, and after all the smoke from lawsuits and finger pointing cleared, they hid their ugly heads for 25 years. In 1995, when you took your 40 watt ballast to the hardware store, it had to replaced by a 34 watt. Now when you take your 34 watt ballast in, you get this little lightweight thing to put in your fixture. “How can I be getting my money’s worth? This thing is too light!”

In 2010, if you had to change your fluorescent fixture, you had to start using those skinny tubes. “Light-weight fixtures and skinny tubes,don’t take me for a fool!” Starting July 14, 2012, the manufacturers will stop making all the old fashioned T12 lamps. With a few exceptions, when you take that 8 foot tube in your garage to get it replaced, or that wimpy 34 watt 4 foot tube in to get a replacement, not only will you have to buy a new fixture, you will also have to take the evil old lamps back with you, because they are now hazardous waste. “These kids now-a-days don’t know nuttin!”

If you are one of the few that read the “Energy Independence and Security Act of 2007” you might make heads or tails of it. If you understood it, then English must be a second language. But the good news is: it’s working for the most part. It is costing us an arm and leg, but it’s working. Now when you and I have the simple job of changing light bulbs, it becomes a major DIY project. It is costing us. Now what do we get out of it? More power. Since it has security in the title, do we get to carry a gun? Heck No!

Out of all the energy used in the US, 25% is used in homes and 19% is used in commercial buildings. It was estimated that energy use would spike 44% from 2005 to 2030. Seven years later it looks like that spike will only be 14%. If you do your math like our politicians, we will save 68%. But it’s 68% of nothing, and this time nothing is a good thing. You can look at it and say we saved 68%, or you can look at it and say we created 68%. It’s not from some new wind, sun, aluminum foil technology, it is a new technology. A technology called “Renewable Energy”.

Now, when you do your honey-dos, whether it’s caulking, insulating, installing blinds, or sitting under the shade of a tree you planted years ago, you know that you are pioneering new grounds.

On the numbers I used, I didn’t just grab the first numbers I found, I did try to check their sources. Probably the best source is EIA Annual Energy Outlook 2008.


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Light Bulbs and Legislation

2012-02-07 by lqlarry. 9 comments

Law HammerI’ve been in the electrical wholesale business for almost 30 years and every day I sell light bulbs.  For over 30 years lamps basically got better, offering more light output per watt on the newer lamps. But recently somebody started taking my light bulbs away.  What am I going to do?  What are all the old people going to use to read their papers?

Younger people tend to understand this, while other people tend to get upset that the government is getting involved in something as simple as light bulbs.  Most people don’t even know it’s happening.  So now I let out the secret.


Rated Lumen Ranges

Maximum Rate Wattage

Minimum Rate Lifetime

Effective Date

1490-2600 72 1,000 hrs 1/1/2012
1050-1489 53 1,000 hrs 1/1/2013
750-1049 43 1,000 hrs 1/1/2014
310-749 29 1,000 hrs 1/1/2014


What does this mean?  On January 1st 2012, 100 watt light bulbs went bye bye.  Well not really.  On  January 1st 2012 light bulb manufacturers could no longer make 100 watt A style lamps (table lamps) for sale in the US.  Then on  January 1st 2013, 75 watt A style lamps are no longer made.  January 1st 2014, 60 and 40 watt go the same way.  All these lamps are available until stock is depleted.

Now, why are they doing this?  After reading and reading and talking to factory reps and some energy specialists, it has to do with building power plants.  The more wattage and kilo-watts saved, the less power used.  DUH.  If energy is saved on a large scale, then enough energy would be saved to avoid building a power plant.  In this age of “not in my backyard”, the legal fees would probably be as high as the cost of building the plant.

Once all the incandescent bulbs are gone, you’ll have to choose between LED and CFL.

Which to use, LED or CFL

Which is better, Compact Fluorescents (CFLs) or LEDs?  I’m not the greenest person in the world and normally don’t go out of my way to be green, other than recycling trash.

Compact fluorescent

At one time legislation was going to cost you big time bucks if fluorescents, including CFLs, were broken.  It was considered a “hazardous spill” and you had to open your windows; if you cleaned it up yourself you would not be able to use a vacuum or broom, only a sticky tape to clean it up.  A professional team did this for a woman in Maine and after everything was done it cost her $3000.00 and insurance did not cover it.  Now, it’s still not a good idea to use a vacuum because of the mercury.

Now all fluorescents are required to be recycled.  Smaller recycle boxes can cost you as much as $1.50 a lamp to dispose.  Some waste companies offer to be open on certain days and be available for you to bring the lamps to them.  Today, with this legislation, nobody ever throws their light bulbs away (wink wink).

Light-emitting diode

LEDs are not cheap, but they are coming down in price.  Right now the biggest change in LEDs is the lumens per watt, or the amount of light coming out divided by the wattage used.  While the wattage on some lamps has not gone up, the light output has.  It was just 2 years ago when the LED manufacturers started making lamps equal to a 75R30 (65BR30), which is the most popular residential light at the moment.  Prices are starting to come down on older technology LEDs, and more and more stores are stocking them.  LEDs contain no mercury, making them easy to dispose of, and no special handling, other than throwing them in the recycle bin.  The energy saving is ridiculous!  I just changed out 7 – 50 watt MR16 lamps with 7 – 6.2 watt dimmable lamps.  That right there is a 87% energy savings, and it cuts out going up and down a ladder 56 times to change the lamps (7 lamps, 8 times).  In this case, CFLs were not an option.

Now the negative about LEDs.  When they first started becoming a reality in residential lighting they were advertised at 50,000 hours lamp life.  Lawsuits happened, causing the big names in LEDs to start advertising 25,000 to 30,000 hours, with some lamps still rated at 50,000 hours.  LEDs lose lumens over time, just like incandescent and CFLs, but LEDs lose more than 3 times that of a CFL:  29% to 9%.

LED's Vs CFL's

So which should I use?

If you need beam control, LED has different beam spreads available, like floods, narrow floods, and spots.  CFLs have none.  LED and CFL fit medium sockets, like table lamps, but while some LED manufacturers do make LEDs to fit in fluorescent sockets, the price for residential use is almost prohibitive.   If you have $3 you can buy a name brand CFL; if you have $25 you can buy some LEDs.  Imports in each kind are cheaper.  Just remember, whichever you choose, it is an investment, but there is most definitely a payback.  
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Poles and Throws

2012-01-10 by tester101. 2 comments

No, we’re not talking Caber Toss here (I don’t have the legs for a skirt… err kilt… call it what you will, it’s still not a good idea to wear it while you’re working around the house).

We’re talking about switches! Specifically those found in your home, used to turn on and off lights and other devices.

First let’s start by defining a switch.  A switch is a device for making and breaking the connection in an electric circuit. A switch can have one or many poles and one or many throws. All switches look about the same on the outside; a lever or button that is flipped or pushed, but internally the number of poles and throws determine how the switch is used.

In a switch, a Pole is the number of circuits that can be controlled by a switch. It might be easier to think of this as the number of inputs. Throws are the number of positions the switch can take. Throws can be thought of as the number of outputs (sort of).

Single Pole Single Throw (SPST)

A single pole single throw switch has one input, and one output. It is used to turn a circuit on, or off. “But wait…” you might be thinking “It turns the circuit on and off, isn’t that a double throw?“. You’re sort of right, I guess I didn’t explain throws so well. It’s not about the physical positions a switch can be in: up or down, it’s about the number of contacts in the switch. Maybe it’s easier to explain with a picture.

As you can see, there is one pole contact and one throw contact. With a SPST switch, turning on and off the light is easy.

Now that we’ve got the concept down, let’s take a look at some other types of switches. Keep in mind that you can have switches with as many poles and throws as you need, but we’re only going to focus on those typically found in residential wiring.

Single Pole Double Throw (SPDT)

A single pole double throw may also be known as a 3-way (2-way in Europe) switch. They are used to control a single device (light, string of lights, etc) from multiple locations.  With this kind of switch, you can turn the light on at the bottom of the stairs.  Then you can walk up the stairs and turn the light off at the top of the stairs. To do this, you’ll need two SPDT switches. One switch at the top and one at the bottom of the stairs. Internally they look like this:

As you can see, the single circuit can be switched between one of two contacts. In the US, these two contacts will be connected using wires called Travelers. These wires connect the contacts of one SPDT switch to the contacts of another SPDT switch (typically).

So how does this turn the lights on and off? Well let’s finish the drawing.

The power from the circuit is connected to one of the switch’s pole contacts, and the light is connected to the other switch’s pole contact. When both switches are in a similar position, electricity flows in the first switch, through one of the traveler wires to the other switch, and finally to the light.

What if I want to control a light from more than two locations?” you might ask. Well, that’s where the next switch comes in.

Double Pole Double Throw (DPDT)

Double pole double throw, also known as 4-way or intermediate switches, allow you to connect as many switches as you’d like into the circuit. Internally they look like this:

To control the light, we’ll add them into the circuit on the travelers between our SPDT switches.

Now the current will flow into the first SPDT switch, out along one of the travelers to the DPDT switch, along one of the other travelers to the second SPDT switch, then finally to the light.

Using DPDT switches, we can control a device from as many locations as we want (within reason). All we have to do is add another DPDT switch, like so:

Understanding switches will help you whether you need to control a single light from one place or a group of lights from multiple locations.   Anything you can imagine can be done, if you choose the right switch for the job.  And please, no kilts while you’re working. It’s just dangerous.

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Ground Pin Up or Down? That is the question

2011-10-08 by Brian. 1 comments


Many people do not consider the positioning of US two prong plus ground pin outlets in their homes. Most prefer the two prongs on the top with the ground pin on the bottom. Maybe it is because it makes a surprising looking face that they can relate.

But the decision can be a matter of safety. In a supplement to one of my Popular Mechanics magazine, another DIYer asked this question and the response made sense:

“…A receptacle outlet can be installed either way….I’ve seen two instances in which thin metal objects fell across the hot and neutral prongs of a card plugged into an outlet…”

A child could also possible put a fork across the two prongs and create a dangerous short. However, for large plugs, having the ground at the top could create unnecessary stress on the plug and cause it to prematurely come out of the socket.

Another option would be to place the socket sideways, but that does not work in some installations. I have seen this in some commercial settings.

As always, remember to check with a certified electrician before performing any electrical work and obtain any permits necessary.


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