This report reanalyzes data from a survey of Ground-Fault Current Interrupters (GFCIs), conducted by the National Electrical Manufacturers Association (NEMA). In that study, participating home inspectors in a number of cities added testing of receptacle and circuit breaker GFCIs to their normal home inspections. The home inspectors reported this data to NEMA. Also as part of the study, homeowners with GFCIs that were found to be non operational were given instructions for free device removal. Removed GFCIs were sent to Underwriters Laboratories. UL conducted further analyses on these GFCIs.

The survey report showed that overall, 14% of circuit breaker GFCIs and 8% of receptacle GFCIs were not operational. Most of the report contains tabulations of the effect of one or more variables at a time on GFCI operability. Tabulations compare the proportion operable in cities with high and low average temperature, high and low humidity and high and low number of lightning strikes and some other variables. The report did not analyze the effect of age on operability, except for a small number of failed devices. The report also contains a single table from a multivariate analysis (ANOVA), showing the simultaneous effects of humidity, lightning and temperature on operability.

Using the survey data that was provided to us by NEMA, we were able to analyze the data for receptacle GFCIs in different ways than presented in the report.

Click here to review this analysis from the U.S. Consumer Product Safety Commission (CPSC) and its findings.

Mike Holt Comment: This is a 10 year old report, we just wanted to pass along the info if you had not seen it previously. If you have any additional updated information please forward it to Mike@MikeHolt.com, and we’ll send out a follow up Newsletter.