Grounds - Who Needs ‘Em?
If you ever lived in a home built before 1962, you have probably noticed these two-prong outlets.
From the 1890s (when homes first were connected to public power) until that point, grounded receptacles weren’t required in most areas of the home. Really, until the 1950s, most home wiring didn’t include a separate grounding wire at all.
What gives? Why didn’t everybody die from electric poisoning?
Ironically, many of those old 2-prong outlets are mounted in metal boxes, connected to the panel by flexible metal conduit or sometimes a separate ground wire strung between the boxes. This provides an effective ground that can be accessed through the cover plate mounting screw. Like this.
Problem is, people rarely use those adapters properly (mounted to the outlet with a grounding screw). Plus, unless you are sure the box is grounded, mounting the adapter might just give you a false sense of safety.
OK, Tom, what should I do?!
Well, if the outlet isn’t damaged, you can leave it alone and only plug in two-prong devices. Or, you can get fancy and replace those old outlets with a GFCI outlet. One of these:
Using a ground fault circuit interrupt (GFCI) doesn’t magically provide a ground path where there wasn’t one before. Used in this situation, they are designed to trip (“turn off”) super quickly if they sense that current between the hot and neutral wire is out of balance … like when you are getting zapped!
So no, all is not lost if you have an old house with old wiring. Of course, it’s more complicated than I’m making it – you might have deteriorated cloth wiring or aluminum or knob and tube needing to be replaced – but the GFCI route is usually the ticket.
Even if you’re not selling, book a maintenance inspection and find out more about the house you’re living in!
From the 1890s (when homes first were connected to public power) until that point, grounded receptacles weren’t required in most areas of the home. Really, until the 1950s, most home wiring didn’t include a separate grounding wire at all.
What gives? Why didn’t everybody die from electric poisoning?
Ironically, many of those old 2-prong outlets are mounted in metal boxes, connected to the panel by flexible metal conduit or sometimes a separate ground wire strung between the boxes. This provides an effective ground that can be accessed through the cover plate mounting screw. Like this.
Problem is, people rarely use those adapters properly (mounted to the outlet with a grounding screw). Plus, unless you are sure the box is grounded, mounting the adapter might just give you a false sense of safety.
OK, Tom, what should I do?!
Well, if the outlet isn’t damaged, you can leave it alone and only plug in two-prong devices. Or, you can get fancy and replace those old outlets with a GFCI outlet. One of these:
Using a ground fault circuit interrupt (GFCI) doesn’t magically provide a ground path where there wasn’t one before. Used in this situation, they are designed to trip (“turn off”) super quickly if they sense that current between the hot and neutral wire is out of balance … like when you are getting zapped!
So no, all is not lost if you have an old house with old wiring. Of course, it’s more complicated than I’m making it – you might have deteriorated cloth wiring or aluminum or knob and tube needing to be replaced – but the GFCI route is usually the ticket.
Even if you’re not selling, book a maintenance inspection and find out more about the house you’re living in!
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