ground conductivity is poor, a ground plate or a group of ground rods electrically connected together will be more effective
than a single ground rod. c Soils. Some types of soil provide better electrical grounds than others Use the type of ground
conductor that works best for the soil In your location Here is a summary of soil types, grounding quality and suggested
type of ground conductor.
QUALITY OF
GROUND
TYPE OF SOIL
GROUND
CONDUCTOR
Fine hard-packed
Very good
MK-2551A/U or
sand with high
Ground rod
moisture content
Clay, loam or shale
Good
MK-2551A/U or
Ground rod
Clay, loam or shale
Poor
MK-2551 A/U,
mixed with gravel or
large buried
sand; or gravel,
metal object,
sand or stone
water pipe or
ground plate.
Loose gravel or
Poor
Large buried
sand surface
metal object, wa-
deeper than 6 in-
ter pipe, ground
ches.
plate or ground
rod.
Permafrost
Poor
Large buried
metal object, water
pipe or MK-2551A/
U if standard
ground rods
cannot be driven.
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