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When Replacing A Light Fixture, What Do I Do With The Ground Wire?

February 25, 2007

Q: I’m trying to replace this old and ugly chandelier over my dining room table. I bought a light that I really like and I was told this would be a straight forward installation. I turned off the breaker and took down the old light. But when I got the light down, I noticed there were only 2 wires coming into the box and they are both black. I didn’t pay attention to how they were connected to the old light. So I asked a friend and he told me to get a magic wand voltage detector. I got one of these and I figured out which wire is the power and which is the neutral.

But there is not a ground anywhere in the box. The old light did not have a ground either. What do I connect the ground wire from my new light to? This above friend told me to connect it to the box. Another friend told me to connect it the the neutral and a third frien told me not to connect it to anything. I’m confused by three different answers. Thanks in advance for your help.

A: This is a common question we get all of the time and I was surprised to see I have not blogged about this yet.

DO NOT connect the ground wire to the neutral. This is very dangerous. The neutral is a current carrying conductor and the ground is not. By connecting the ground to the neutral, you will have current on everything metallic that is connected to this ground wire.

You usually can’t go wrong by attaching the ground wire to the metallic box with a green ground screw. However, if the box is not grounded this will do nothing.

If your wiring is installed in conduit or BX cable, your light box may be grounded. The way to determine this is to carefully test for a ground. This part is dangerous and if you are unsure of what you are doing or uncomfortable working with live electricity, I recommend hiring a licensed electrician. 

First, place a wirenut on the neutral conductor and bend it out of the way. Now place a wirenut on the power supply wire and go turn this circuit on. Next, wear a pair of leather gloves and get a voltage tester. Finally, wearing your leather gloves, remove the wirenut and check for voltage between the hot wire and the light box. If there is approximately 120 volts, your box is grounded.

Now just because you are wearing leather gloves, do not think you are superman and invinsible against live electricity. Leather gloves only provide a limited amount of insulation between you and the live conductor.

Make sure you turn off the power again to this circuit before continuing with your installation.

If you need further clarification or have more questions, please submit them in the comment section of this post.

Zoeller Pump Co. Recalls Septic Pumps Due to Shock Hazard

February 23, 2007

Zoeller Pump Co., of Louisville, KY is recalling about 2,300 Zoeller Brand Septic Pumps with a 20-foot black cord with a plug. The plug on the pumps could have a grounding problem that could pose an electrical shock hazard to consumers.

The pumps have date codes 0906 and 1006. On models 53, 57, 151, 152 and 153 the date code is printed on the nameplate on the top of the pump. On Model WM48 the date code is printed on the tag near the plug. “Philippines” is stamped on the plug. A list of specific part numbers, model numbers, date codes and UPC codes can be found at www.zoeller.com. Pumps that have already been hard wired during installation (where the plug has been removed) are not included in the recall.


Click to enlarge

These pumps were sold by Zoeller distributors nationwide from September 2006 through December 2006 for between $125 and $375. The cord and plugs were manufactured in the Philippines and the septic pumps were manufactured in the U.S.

Consumers should contact Zoeller to schedule an inspection, replacement and return of affected pumps. You may do so by calling (800) 928-7867 between 8 a.m. and 4:30 p.m. ET Monday through Friday, e-mail Zoeller at customercare@zoeller.com, or visit the firm’s Web site at www.zoeller.com.

How to Install a Dimmer Switch

February 22, 2007

This is a simple project that most homeowners can tackle themselves and complete in less than 30 minutes.

The first thing you need to do is determine which size and type of dimmer switch you need to install.

Sizing your dimmer switch is very easy. Dimmer switches are rated according to the lighting load they will dim. Let’s say you want to dim your dining room chandelier. This chandelier has 8 – 100 watt light bulbs in it. This means that the total lighting load you want to dim is 800 watts. You can reduce this load by changing the light bulbs to 60 watts each. This would give you a total lighting load of 480 watts.

The smallest dimmer switch you can get is 600 watts. From here the next size is 1000 watts, 1500 watts, 2000 watts, etc… The 600 watt and 1000 watt dimmers are the most common. Anything above 1000 watts will no longer fit into your standard single gang switch box. These larger switches typically require their own 2-gang switch box.

Now let’s talk about type; I would like to discourage you from getting those cheap rotary style dimmers. These control the light level through a variable resistor. Less resistance increases the light level and more resistance decreases the light level.

The problem with this solution is that you end up using a lot of energy to heat the resistor, which doesn’t help you light up the room but still costs you. In addition to be being inefficient, these switches tend to be cumbersome and potentially dangerous, since the variable resistor releases a substantial amount of heat.

The newer style resistors rapidly turn the light circuit off and on to reduce the total amount of energy flowing through the circuit. This results in better efficiency and less energy loss through heat. To learn more about this style, I recommend reading “How Dimmer Switches Work“.

You also need to determine if you need a single pole or 3-way dimmer switch. A single pole switch will only turn on or off the light from 1 switch. A 3-way switch will turn on or off the light from 2 or more switches.

With 3-way switches you only need to replace 1 of the 3-way switches with a dimmer. If you want to dim your light from multiple switches in a 3-way circuit, you will need a master and slave(s) combination. The Lutron Maestro series is one I recommend here.

To replace your switch, you first need to turn off the power supplying this circuit. Now go remove the cover plate and use a voltage tester to ensure that the power is indeed off. Never assume the power is off. I have seen some very scary stuff over the years, resulting in me getting shocked by assuming the power is off. Never assume the power is off and always test before touching any wires or devices.

Loosen the screws on your old switch and pull it out of the box. Now, before you disconnect the wires, make a note of how they are connected to your existing switch. This is very important to make your 3-way switches work porperly. I recommend writing this information down or taking a picture with a digital camera.

When reconnecting your dimmer switch, it is very important to ensure the ground wire is connected to the new dimmer. If the dimmer switch has screw terminals to connect your wires to, be sure you wrap the wires clockwise around the screw terminals. This will allow the loop in the wire to close with the final turn of the screw resulting in a better electrical connection.

If you have questions or need further clarification on this matter, please submit your questions in the comment section of this post.

Grounding Your Ungrounded Electrical Receptacles

February 21, 2007

I have an older home with 2 prong receptacles and I need to ground them. How do I do this?

This is a common question I see all of the time on Yahoo! answers. I am often frustrated by the answers given by all of the self-proclaimed experts. I recommend not using Yahoo! answers for your electrical questions and consulting with a local electrician, your local building codes department or ask your question on this blog.  

So, let’s clear up a couple of things. You are not permitted to run a ground wire to the closest metallic water line, metallic pipe, gas line or drive a separate ground rod. These are the answers that I often see and this is very dangerous.

Let’s start with the water line. Let’s say you had a metallic water line break and a plumber repaired it with the new pex piping. If you have a fault, the electricity has no place to go. The pex pipe is not metallic, therefore your entire water system would become live. I’m sure you can imagine how dangerous this is. 

Your water meter will also have rubber or neoprene bushings on each side of the connection. These bushings break the continuity of your water line so, connecting a ground wire to any point on your metallic water line will do nothing. The original electrician that wired your house was supposed to run a ground wire to the street side of the water meter first and then install a jumper across the water meter. However, this was not done is older homes.

You are never permitted to run a ground wire to a metallic pipe or gas line. Yes, the gas line is required to be bonded, but you can’t ground to it. Never connect any wire, cable or conductor to your gas line.

To properly ground your receptacles, you need to run a ground wire to the equipment grounding terminal bar within the electrical service box on the outside of your house or in your breaker box. You are also permitted to run a ground wire to any accessible point on the grounding electrode conductor. The grounding electrode conductor in a house is the wire that attaches to either an 8′ ground rod, within 5′ of the water meter or to a concrete encased electrode (ufer ground).

If you have a home with the 2 prong receptacles, chances are that you have the old knob and tube wiring. I recommend replacing this and run a new 2 conductor cable with a ground back to your breaker box. The problem with the old knob and tube wiring is it has cloth insulation which breaks down, then becomes very brittle and ineffective.

To learn more about grounding requirements, get a copy of the current edition of the National Electrical Code® and read article 250. To verify the grounding requirements for ungrounded receptacles read section 250.130(C).

If you just need a 3 prong receptacle, you are permitted to install a GFCI receptacle in place of the 2 prong receptacle [NEC section 406.3(D)(3)]. These GFCI receptacles need to be marked as having “no equipment ground”. However, just installing a GFCI receptacle does not ground the receptacle.

If you have questions or need further clarification please submit your questions in the comment section of this post. 

 

Advice for Planning Your Electrical Service in a Garage

February 20, 2007

Q: I am planning the electric service in a new, attached 2 1/2 car garage. I’m trying to anticipate future uses and don’t want to miss obvious issues that a pro would spot immediately. I am thinking of a subpanel with 60A of 240V service to feed about 5 circuits: 2 with general purpose outlets, 1 for opener outlets, 1 for lighting, and 1 for a future heater. Switches and outlets will be 42-48″ off the floor. Outlets will be about 7′ apart. What would you change, add or otherwise recommend? Thanks in advance

A: Garages are difficult to plan for everything. You may use it as a wood working shop and the next homeowner may use it as a mechanic’s garage.

I recommend installing a 100 amp sub-panel instead of the 60 amps you are planning. The 60 amp sub-panel will work fine for your needs, but there will almost certainly be a need for more power in the future. I have seen a lot of homeowners install 50 amp welders or 30 amp compressors in their garages.

In a garage, we typically install all receptacles at 42″ to the bottom of the box. This allows for the receptacles to be above any future work benches that may be installed. All receptacles are required to be GFCI protected in a garage.

However, there is an exception to the GFCI protected receptacles if you are going to have a freezer or refrigerator in your garage. The receptacle that feeds you freezer or refrigerator doesn’t have to be GFCI protected. A GFCI will typically nuissance trip with a freezer or refrigerator due to the motors in them. I recommend installing these items on a dedicated circuit. Your garage door opener receptacles do not need to be GFCI protected either.

I also like to install a conduit from the breaker box to the attic space above the garage. This allows you or a future homeowner access into the breaker box to add more circuits. Here I would install a 1″ electrical non-metallic tubing (ENT) conduit to an accessible point in the attic above the garage. This ENT is also referred to as smurf tube. This is the blue, flexible non-metallic conduit. You will find this at your local home improvement center or electrical supply house.

 

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