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Old 3rd Oct 2012, 1:49 pm   #11
G8HQP Dave
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Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
Default Re: 13 amp plug question

According to Wikipedia the hole was for inspection of the earth connection (see caption under picture on right), and was a requirement of the original 1947 version BS 1363. Presumably dropped in a later revision.
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