Building codes require ground-fault circuit interrupters (GFCI) on every electrical outlet near plumbing fixtures or wet areas to protect against electrocutions. But before a GFCI can protect you, it may need protection against lightening. According to Occupational Health & Safety magazine:
“Built into the [GFCI] is a metal oxide varistor (MOV) used as a surge suppressor. The MOV absorbs the voltage surge and converts it into heat. Repeated surges can degrade the MOV, still allowing current to flow but not providing the protection required. Voltage surges such as lightning strikes in the area can cause a surge… This is a primary cause of GFCI failures…”
Researchers at the International Association of Electrical Inspectors found that, in regions with frequent lightning, “up to 58 percent of the GFCI circuit breakers were defective…”
Bottom Line: GFCI should be tested every month. In buildings where occupants might neglect testing, however, a lightning protection system can protect the devices that protect the people.
Credit: Photo by Wtshymanski [CC BY-SA 3.0]