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Thursday, August 3, 2017

Question:

Please keep up the good work. UF cable; what column of the table 300.5 would you use for residential?  Column 1 is what I say 18 inches below grade. But Column 4 shows 12 inches if GFCI protected and 20 amp circuit or less. Please explain.

Thanks, Brett Howard

A

Answer:

Hey Brett thanks for your question and the kind words. Column 1 of Table 300.5 is used for direct buried cables and the general burial depth is 24 inches in the top row. Under 2 inches of concrete in a trench, under a 4 inch exterior slab, or under some dwelling driveways and parking areas is reduced to 18 inches of cover. If you meet the conditions in Column 4 - residential, 120 volts or less, 20 ampere maximum overcurrent protection, and GFCI protection then a 12 inch burial depth is allowed as a general rule.

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