[Elecraft] Much OT - No "practical" solution

[Ron D'Eau Claire]

That's what I said, Don. Most commercial appliances depended upon
insulation. I had a commercially sold Meissner kit with a metal case that
was tied to one side of the mains, but that was rare by post WWII. Most
appliances of that day were insulated. 

For example the common AC/DC table radios of the day all had Bakelite cases
and knobs intended to insulate the user from possible harm. Even equipment
with a metal case, like my old Hallicrafter's S-38 receiver, had the hot
chassis carefully insulated from the metal cabinet using rubber grommets,
etc. 

And yes, some appliances leaked a bit of a-c, producing that "tickle". Like
I said, insulation practices are better today. 

I'm only noting that that design practices has returned. Few modern
appliances intended for use in the bath, kitchen, or outdoors are equipped
with a safety ground. 

And I agree, GFI protection has offered a huge improvement, but what is it's
effect? It makes the three-wire grounded outlet even less important! 

Ron 

-----Original Message-----
From: Don Wilhelm [mailto:w3fpr at embarqmail.com] 
Sent: Sunday, November 25, 2007 5:44 PM
To: Ron D'Eau Claire
Cc: 'Elecraft Mailing List'
Subject: Re: [Elecraft] Much OT - No "practical" solution


Ron,
On all of the modern 2 wire appliances that I have, there is no exposed 
metal - it is all plastic or otherwise insulated.
There was an appliance designation that is termed "Double Insulated" 
that used to be in common use. Double Insulated devices depend on the 
fact that you cannot touch any part the can connect ot the electrical 
circuits, even under fault conditions, and no 3rd ground wire is 
required for them.
The equipment of the 40s and 50s often used metal cases that were 
connected to nothing - until a fault occurred.  I used to have some of 
those old drills that produced quite a 'tickle' when operated outside or 
if slightly damp.  That was when I was much younger, and I sometimes 
wonder how I survived, but am glad I did.
73,
Don W3FPR

Ron D'Eau Claire wrote:
> Has anyone noticed how little that "safety ground" is used by 
> commercial products these days?
>
> Few, if any, household appliances such as vacuum cleaners or even 
> kitchen appliances use it now. They all have two-wire plugs. For 
> outdoor use I have a electric chain saw, and electric circular saw, an 
> electric weed-whacker, an electric lawn mower and an electric hedge 
> trimmer NONE of which use a 3-wire cord. They were all purchased in 
> the last five years.
>
> All of these devices revert to the standards of the 1940's and 50's, 
> relying on insulation without a "safety ground" tied to a metal 
> enclosure. The insulation is probably better than was used in the old 
> gear, but it's the same old design.
>
>