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When did metal water pipe become no longer allowed as the only ground for a house electrical system?
Thursday, August 1, 2019
The 1978 edition of the National Electrical Code (NEC) eliminated the option to ground a home’s electrical system to the water pipes. We still occasionally see the ground wire running to a clamp around a hose faucet for the ground of a very old electrical system that has not been updated. But many times it has been converted to a bonding connection for the water pipe and a ground rod now provides the primary ground.
The reason for the rule change was the increasing popularity of PVC and CPVC plastic pipes in the 1970s, which are not electrically conductive. Repairs with the plastic pipe can break the electrical continuity of the ground connection of copper or galvanized steel pipe. Most grounding today is done with a driven metal rod (above) or ufer to foundation steel (below).
But, while the year that the NEC made this change is easy to define, each local juridiction’s building codes don’t necessarily adopt the latest edition of the NEC immediately. The state of Florida, for example, did not make the 2011 NEC effective until mid-2015. Other jurisdictions have sometimes waited even longer to adopt a newer NEC edition and, to complicate things further, they might make amendments that exclude parts of the newest requirements. So the year when an NEC change is published can be several years before your local building department adopted that edition of the code and began enforcing it.
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