HANDBOOK REQUIREMENTS - Central Maine Power Company

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electrode/conductor or metallic conduit is not accessible, a UL
listed meter box ground clamp may be installed; provided it is
not attached to, nor does it interfere with operation of, the meter
enclosure cover. Any metal piping system installed in, or attached
to, a building or structure; and any steel building frame
shall be
bonded in accordance with NEC Section 250.104.
Bonding on the line side of the service overcurrent device
must be "ensured." Metal conduit and enclosures containing
service conductors shall be effectively bonded together in
accordance with the requirements of NEC Section 250.92.
Suitable bonding methods include, but are not limited to: threaded
couplings and hubs, listed bushings with bonding jumpers, and
listed bonding-type locknuts. Bonding jumpers shall be used
around concentric or eccentric knockouts. Standard locknuts or
bushings shall not be the sole means for the bonding required for
services. All bonding jumpers (intended to conduct fault current),
on the line side of the service overcurrent device, shall be sized in
accordance with NEC Section 250.102 (C); i.e., sized to NEC
Table 250.66, the same as, grounding electrode conductors.
Bonding is effective as a means to prevent or mitigate
problems due to the phenomenon commonly called stray voltage.
The Company recommends that provisions be made to bond any
steel reinforcing mesh or rod to the electrical grounding system
whenever any concrete slabs are poured. This is particularly
important for dairy barns and houses constructed on concrete slab
foundations. Refer to NEC Section 547.10 for information
regarding bonding and equipotential planes in agricultural
buildings.
It is recommended that, whenever work is in progress on
any premises, contractors inspect the condition of all grounds and
bonds and call the owner's attention to any which may be broken
or missing. The connection to a metal underground water system