I am dressing up an old house (1935) for resale and want to install new plugs and switches and covers. The house has knob and tube wiring still on most circuits and therefore no grounding. I worry about selling the home to someone who doesn’t realize that there is no ground even though the new plugs will have accept grounded cords. A friend suggested installing GFIs in all of the plugs. Does this represent a viable solution? Any suggestions would be appreciated. Rewiring the whole house is not in the budget!
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
A standardized approach, quick-to-install hardware, and a simplified design make building custom casework cost-effective.
Featured Video
How to Install Exterior Window TrimHighlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
You can purchase receps that accept only 2 prong plugs. There is no ground. Used them myself for the same reason.
It is legal to replace ungrounded outlets with GFCI's. You need a label (which comes with most of them) that indicates that they don't have a phyiscal ground. But the provide the same personal protection a grounded outlets, but does not give full protection against surge protection if used with a surge protection devices.
You can also use the GFCI to feed downstream grounding sytle outls.
For critical appliacnes like refierators and sump pumps it is best to run a new grounded circuit or add a separate ground wire that runs back to the pannel or another grounded circuit (not to the nearest water pipe as was done in the past).
Yep, the "right" answer is to install GFCIs anywhere where you need a 3-prong outlet, labeling the outlet "ungrounded". Definitely DO NOT just install ungrounded 3-prong standard outlets -- very illegal and very unsafe. 2-prong outlets are still readily available and should be used to replace old outlets where needed.
FWIW, I've heard a lot of folks claim that the "ungrounded" labels come with most GFCIs, but have yet to actually see a GFCI package containing the labels. We must run in different circles, I suppose. But presumably just (neatly) writing "ungrounded" on the outlet with a fine-point felt pen is sufficient.
Of course, if at all possible, outlets in the kitchen, bath, "computer room", and laundry area should be rewired for true 3-prong support.
Where is this? I'm surprised to find K&T in a 1935 building. Around here they were doing everything in black pipe starting in the early 1920's.
-- J.S.
John,
There are big regional differences in the wiring methods used in houses at any given point in time. A lot of it depended on the preferences of the electricians doing the wiring, and the inspectors. Just like today, there were people who wanted to stay with the status quo ("if it ain't broke,..."), and others who wanted to use newer technology.
K & T was used from early 1900s to post WWII, depending on location and the cost of the house. In my own neighborhood, built just pre-WWII, the very deluxe houses were wired in EMT, and all the rest in K & T.
In a lot of areas, BX displaced K & T in the late '20s.
And of course, in Chicago, everything has to be in EMT, to this day.
Wire in black iron pipe (heavywall)? Where are you? A place built is 1935 is late for this, but often when electricity was installed in houses that were plumbed for gas light, the gas piping was used as conduit for the wiring.
Cliff
I'm in Los Angeles. The black pipe era here seems to run from about WWI through WWII, with flex in the '50's and Romex starting in the '70's.
-- J.S.