Bonding at the service

There are a few systems that may be installed in your house which will need to be bonded to the service. The method of bonding these systems is essentially the same as grounding to your ground rods. Simply run the proper sized wire, connect to the clamp that you have secured to the pipe, and connect the other end to the ground bar at the main breaker panel or meter main panel. In the event you have a 320A service with two main breaker panels, unlike grounding, you need to bond to only one panel. Bonding clamps come in all sizes, for different pipe sizes, but are essentially the same as ufer clamps, with the exception that pipe bonding clamps can be made of aluminum instead of brass.

Metal water pipe

Although rare in new houses today, copper water pipe is still used in some areas and metal water pipe was common years ago. All metal water pipe needs to be bonded. It can be bonded at any convenient and accessible point in the system. The COLD water pipe is the one to bond to. The most common place to bond the water pipe is where it is stubbed out of the wall at the water heater. Simply run your wire down inside the wall, stub it out on top of the cold water pipe, and install your clamp. If you are running to a 200A main breaker or meter-main, the same #4 copper you used for the grounding electrode conductor will suffice. If you are running to a 320A meter-main, you will need to use 1/0 copper.

Metal gas pipe

Note! This one has become a bit controversial lately. In some areas they have made the interpretation that you are NOT to bond the gas pipe. Check with your local inspector on this one. If you have a house with natural gas, you may need to bond the metal gas pipe. You can bond it at any convenient and accessible spot on the customer side of the gas meter. If your gas meter is close to your service, just run a piece of the same #4 you used for your grounding electrode conductor, stub it out of the wall on top of the customer side pipe of the gas meter, and connect it using the proper size bond clamp. Where your service is not close to your gas meter, you can bond the gas pipe at the largest gas appliance that also takes power (usually the furnace). Simply connect a piece of #10 copper to the ground in the make-up box in the furnace, and connect it to the gas nipple feeding the furnace with the proper size bond clamp.

Gas line bonding

Other metal piping

Though rare, if you have any other metal piping in the house, such as air or a fire sprinkler system, these need to be bonded also. The method is the same as for the metal gas pipe.