National Electrical Installation Standards

Standards as High as Your Own

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Thursday, December 30, 2004

Question:

I’m installing a receptacle in a residential crawl space to be used for feeding the heat tape for the cold water piping. The crawl space is partially enclosed and not heated. Should this receptacle have ground-fault protection for personnel?
A

Answer:

NEC 210.8 (A)(4) requires all 125-volt, single-phase, 15 and 20-ampere receptacles installed, in crawl spaces that are at or below grade level, to have ground-fault circuit-interrupter protection for personnel. NEC 210.8(A)(3) has an exception exempting outdoor receptacles that are not readily accessible and are supplied by a dedicated branch circuit for de-icing equipment from having GFCI protection. But then they require protection according to 426.28, which requires ground-fault protection of equipment. If the residence you are working on is a mobile home or a manufactured home, NEC 550.13(E) requires that a receptacle outlet for connection of pipe heating cables must be on the load side of a ground-fault circuit-interrupter. Ground-fault circuit-interrupters (GFCIs) or 5-mA trip level devices are personnel protective devices and may be too sensitive. Heating cable circuits can produce up to 10-mA of leakage under normal conditions. Install 30-mA equipment protective devices to eliminate nuisance tripping. Don't use other than a single receptacle (i.e., a duplex) unless you are feeding more than one heat tape and be sure the receptacle has a rating not less than the rating of the branch circuit (210.21(B)(1).

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