Choosing The Best Grounding Materials

Grounding and Safety Go Hand in Hand

By Timothy Thiele, 

A grounding system is comprised of a ground rod, wiring to connect it to a service panel or utility meter base grounding lug, and a ground buss. It is a very important part of your electrical system to ensure electrical safety. According to The NEC, you should have a grounding resistance of 25 ohms or less, meaning it may be necessary to drive more than on ground rod, also known as grounding electrode

1. What Are Ground Rods?

Ground rods are used to connect the grounding system of electrical systems to earth ground. Ground rods are manufactured of many different materials, although the two most popular are probably made of copper clad or galvanized steel. These materials are very good conductors of electricity and allow any dangerous electricty to flow to ground, taking the danger away from you and the electrical panel.

3. What Diameter Ground Rod Is Needed?2. How Long Are Ground Rods?

Ground rods come in both 8' and 10' lengths, however, an 8' ground rod is the common size used in residential installations. As a rule, ground rods must be a minimum of 8' long, so do not cut them off! If you are in very dry ground, you may want to consider a special clamp that allows you to stack ground rods.

Another option is to add a second ground rod, which is a better option, but remember that the NEC requires them to be a minimum of 6' apart. If possible, try to get the ground rods in a moist area around your home. Usually, the area close to the exterior wall has enough moisture due to runoff water from downspouts.

Ground rods come in varying thickness that include 3/8", 1/2", 3/4", and 1". The minimum diameter ground rod allowed is 3/8".

4. What Type Of Grounding Wire Do I Need?

Although there are many types of wire, including copper and aluminum, copper is the best for connecting to earth ground. You see, the ground wire, often referred to as the grounding electrode conductor, is the link between the ground rod and the service ground connection. Usually a #6 wire is used to make this connection, but a larger wire may be used to make a bigger connection if you'd like. In larger electrical service installations, a larger ground wire would be needed.

5. What are Grounding Clamps?

Grounding clamps are used to connect the grounding electrode conductor to the ground rod. There are mechanical clamps that have set screws taht tighten the clamp around the ground rod to form a connection.

An acorn clamp is an oval-shaped clamp with a bolt used to tighten it to the ground rod. An acorn clamp is the most commonly used clamp for ground rod connections and is approved for direct burial applications.Th grounding conductor should be attached against the ground rod and in the "v" of the acorn clamp, opposite the bolt side of the clamp.

The brass-toothed clamp is a two-piece clamp that has two setscrews used to attact it around the ground rod. Then, it also has a center point that has a hole to mount the wire and a setscrew to tighten the wire. This type clamp is best used inside to make grounding connections around water pipes that are grounded to the ground buss of your panel.

It is unwise and unsafe to install the shorter, 4' ground rods often sold for grounding things like TV antennas and oher indivdual devices. Protect your equipment by installing the proper length ground rods! Besides, the shorter rods, although they may be easiler to install, are not legal and can actually cause your grounding system to fail if used.

6. Cad Welds For Grounding

Cad welds are often used on commercial and industrial installaions, quite frankly because they are a secure and reliable grounding connection. To install such a connection, a mold and shot of molding mixture is used. To do this, the mold is clamped around the ground rod, a small chrome-colored disk is inserted to hold the mixture in the mold until lit, the mold mixture is inserted, the mold cap is lowered into position, and via a hole in the mold cap area, the mold is lit, usually with a striker or torch. The mixture fires like a rocket taking off and molten mixture is adhered to the rod, encompassing the rod and ground wire. After the mixture cools, the clamp is removed. If the connection is secure, you have a successful grounding connection.

7. Grounding For Safety

You may ask, "what needs grounding"? In my years of electricianing, I'd say the answer is everything and anything you can. If you ground all of your electrical boxes, devices, tools, equipment, and water pipes, if they aren't plastic water lines. You'll notice that devices like switches and outlets all have ground screws on them now, so use them!