Nec Service Grounding Chart

Table 250 102 c 1 from the 2014 nec.

Nec service grounding chart. Metal parts of electrical race ways cables enclosures or equipment must be bonded together and to the supply source in a manner that creates a low impedance path. Nfpa 70 national electrical code table 250 95. In earlier codes all these conductors as well as the grounding electrode conductor were selected from table 250 66.

2017 nec study guide for grounding electrode systems this study guide was prepared by gaylord poe few things are more frustrating for an electrician than trying to figure out how the nec rules for service grounding and bonding are going to be interpreted and enforced by the local electrical inspector. Grounding electrode conductor for ac systems. Ambient temperature correction factors based on 30 c 86 f table 310 15 b 3 a ccc count adjustment factors.

Not exceeding amperes copper awg or kcmil. 58 mike holt s illustrated guide to understanding 2017 nec requirements for bonding and grounding 250 4 grounding and bonding 5 effective ground fault current path. Article 250 is the largest article in the nec and yet for years the article has only had the following two tables.

120 240 volt 3 wire single phase service entrance conductors service lateral conductors and feeder conductors that serve as the main power feeder to a dwelling unit and are installed in raceway or cable with or without an equipment grounding conductor. Rating or setting of automatic overcurrent device in circuit ahead of equipment conduit etc. Ground wire size table.

Table 250 66 for sizing grounding electrode conductors of alternating current systems. A new table has been added to article 250. Table 250 122 for sizing equipment grounding conductors.

This table lists the minimum sizes of grounding conductors for grounding raceways and equipment. Supply side grounded and bonding conductors are sized from table 250 102 c 1 in the 2014 nec. Size of largest ungrounded service entrance conductor awg kcmil size of grounding electrode conductor awg kcmil.

Mike holt s illustrated guide to understanding 2011 nec requirements for grounding vs. It is very helpful to have a separate table for selecting the. Minimum size equipment grounding conductors for grounding raceway and equipment.

Just review the table below. The current path shown between the supply source ground ing electrode and the grounding electrode at the service main shows that some current will flow through the earth but the. Grounding electrode system utility transformer service conductor service disconnect feeder branch circuit sub panel main bonding jumper 250 102 c grounding electrode conductor 250 66 grounding electrodes 250 50 bonding of devices 250 134 t250 122.