What is the grounding requirements for a residential home?
Depending on your locality, these requirements may differ from what is specified by the National Electrical Code (NEC or "code"). The NEC is commonly regarded as the minimum requirements for electrical installations, and many states adopt it without modification as their requirements, too. Still others modify it and some counties and towns further modify the code. It is for these reasons, you should consult your local code enforcement office to learn what the authority having jurisdiction (AHJ) wants to see when (s)he inspects the work.
Typically, an 8' grounding electrode (or ground rod) is driven into the ground and an approved clamp is used to secure an unspliced grounding electrode conductor to the neutral bar in the meter socket or service entrance equipment. The size of this conductor is based on the service entrance (SE) conductors. Typical sizes are when:
100 amp SE conductors are #4 copper (CU) or #2 aluminum (AL), requires a #8 CU or #6 AL grounding electrode conductor.
150 amp SE conductors that are #1 CU or 2/0 AL require a #6 CU or #4 AL grounding electrode conductor.
200 amp SE conductors that are 2/0 or 3/0 CU or 4/0 or 250 AL require a #4 CU or #2 AL grounding electrode conductor.
You may be required to provide a secondary grounding electrode if you can not provide data supporting minimum soil resistivity to the AHJ.
Lastly, bonding of the residence's cold water pipes is required. A #8 is used for 100 amp services and #6 for up to 200 amp services. If on a public water supply, the bonding conductor must be connected on the street side of the meter and the house side of the meter (should the meter be removed there will be no voltage present to injure the person removing the meter) to the grounding electrode conductor termination bar in the meter socket or ground bar in the service entrance equipment. Installation and connection of an IBT (Intersystem Bonding Terminal) is required for telephone, cable TV, etc. You may need to bond gas piping and metal duct work., and some locations specifically prohibit bonding one or more of these items.
The short of this is you must determine the requirements of your locality. The AHJ can tell what they are - but will probably not tell you how to do it.
I hope this was helpful.
Feb 23, 2012 |