could have saved my life.

I was in my workshed which is about 60 ft from the house drilling some
aluminum. I got a faint tingle in my hand, I touched the case of my
drill a couple times and didn't feel any thing, so I started to drill
again. I noticed the tingle again, I went through this a few times until
I decided there's a problem. The tingle was at a tiny red spot on my
finger, I later removed a small metalic sliver. If not for the sliver I
probably would not have noticed the missing ground, for I don't know how
long.
The drill motor is a 3 wire system, hot, neutral and ground. I had it
plugged into a GFCI. I unplugged the drill and pushed the test button.
The GFCI didn't pop. I retrieved my DVM and tested from the drill case
the the dirt outside the door, it was about 80v. I then tested from the
Hot to the ground at the receptacle, that was about 20 v. I moved to
another Receptacle closer to the house, same thing no ground connection.
I moved up to a receptacle on the outside of the house on the same line,
again no ground connection. Inside the garage, no ground connection. I
opened the circuit breaker box and checked the ground wire, it is good.
So, in my attic between the CB box and the garage there must be a
connection box where the ground has opened up.
Followup tomorrow evening.
Mikek

In sci.electronics.repair amdx wrote:
could have saved my life.

Good catch.

I unplugged the drill and pushed the test button. The GFCI didn't
pop.

The "test" button on the GFCI should work even if there is no ground to
the GFCI. So you may have more than one problem here.

Inside the garage, no ground connection. I opened the circuit breaker
box and checked the ground wire, it is good. So, in my attic between
the CB box and the garage there must be a connection box where the
ground has opened up.

Don't discount the idea that the ground is open at one of the
receptacles. In three houses I've worked on (one from 1965, two from
1969), if two or more NM cables come into a receptacle box, the ground
wires are just twisted around each other for an inch or two, with no
wire nut. Usually the contact between wires is OK but sometimes the
twist is not very strong. One of the ground wires is longer than the
others, and it goes to the green screw on the receptacle. When I swap
a receptacle in a box like this, I usually add a green wire nut with a
hole in the top for the long ground wire (Ideal "Greenie" or equal), to
help make sure the ground stays connected.

Besides, checking the receptacles is probably easier than fooling around
in the attic.

A good tool for quickly checking grounds is a 100 W incandescent lamp
in a socket that has insulated wire leads. Connect the wires live to
neutral to calibrate your eyes, then go from live to ground. If the
brightness drops off a lot, the ground has high resistance. (If there
is a GFCI in the circuit, going from live to ground should also pop the
GFCI.)

Matt Roberds

On 5/2/2014 8:58 PM, wrote:
In sci.electronics.repair amdx wrote:
could have saved my life.

Good catch.

I unplugged the drill and pushed the test button. The GFCI didn't
pop.

The "test" button on the GFCI should work even if there is no ground to
the GFCI. So you may have more than one problem here.

Inside the garage, no ground connection. I opened the circuit breaker
box and checked the ground wire, it is good. So, in my attic between
the CB box and the garage there must be a connection box where the
ground has opened up.

Don't discount the idea that the ground is open at one of the
receptacles. In three houses I've worked on (one from 1965, two from
1969), if two or more NM cables come into a receptacle box, the ground
wires are just twisted around each other for an inch or two, with no
wire nut. Usually the contact between wires is OK but sometimes the
twist is not very strong. One of the ground wires is longer than the
others, and it goes to the green screw on the receptacle. When I swap
a receptacle in a box like this, I usually add a green wire nut with a
hole in the top for the long ground wire (Ideal "Greenie" or equal), to
help make sure the ground stays connected.

Besides, checking the receptacles is probably easier than fooling around
in the attic.

A good tool for quickly checking grounds is a 100 W incandescent lamp
in a socket that has insulated wire leads. Connect the wires live to
neutral to calibrate your eyes, then go from live to ground. If the
brightness drops off a lot, the ground has high resistance. (If there
is a GFCI in the circuit, going from live to ground should also pop the
GFCI.)

Matt Roberds

checking in receptacle boxes, I thing I have it somewhat isolated.
The CB box and the garage are on opposite ends of the house, and as far
as I know, the garage is on a breaker by it's self. But it also looks
like there is a connection box between the CB box and the garage, or at
least a break in the ground wire. It seems a little odd, I'll figure it
out this afternoon.
Mikek

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"amdx"
could have saved my life.

I was in my workshed which is about 60 ft from the house drilling some
aluminum. I got a faint tingle in my hand, I touched the case of my
drill a couple times and didn't feel any thing, so I started to drill
again. I noticed the tingle again, I went through this a few times until I
decided there's a problem. The tingle was at a tiny red spot on my finger,
I later removed a small metalic sliver. If not for the sliver I probably
would not have noticed the missing ground, for I don't know how long.
The drill motor is a 3 wire system, hot, neutral and ground. I had it
plugged into a GFCI. I unplugged the drill and pushed the test button.
The GFCI didn't pop. I retrieved my DVM and tested from the drill case the
the dirt outside the door, it was about 80v. I then tested from the Hot to
the ground at the receptacle, that was about 20 v. I moved to another
Receptacle closer to the house, same thing no ground connection. I moved
up to a receptacle on the outside of the house on the same line, again no
ground connection. Inside the garage, no ground connection. I opened the
circuit breaker box and checked the ground wire, it is good.
So, in my attic between the CB box and the garage there must be a
connection box where the ground has opened up.
Followup tomorrow evening.

** FYI:

GFCIs work independently of the safety ground in a 3 wire system - so will
still trip if a few mA of current is passing to any local ground like soil,
wet concrete or metal plumbing.

However, a missing safety earth conductor is never good as the metal cases
of 3 wire appliances can become live and nothing blows.

BTW:

I have not seen a 3 wire, hand held drill in quite a while.


.... Phil

On 3/05/2014 12:01 PM, Phil Allison wrote:
"amdx"
could have saved my life.

I was in my workshed which is about 60 ft from the house drilling some
aluminum. I got a faint tingle in my hand, I touched the case of my
drill a couple times and didn't feel any thing, so I started to drill
again. I noticed the tingle again, I went through this a few times until I
decided there's a problem. The tingle was at a tiny red spot on my finger,
I later removed a small metalic sliver. If not for the sliver I probably
would not have noticed the missing ground, for I don't know how long.
The drill motor is a 3 wire system, hot, neutral and ground. I had it
plugged into a GFCI. I unplugged the drill and pushed the test button.
The GFCI didn't pop. I retrieved my DVM and tested from the drill case the
the dirt outside the door, it was about 80v. I then tested from the Hot to
the ground at the receptacle, that was about 20 v. I moved to another
Receptacle closer to the house, same thing no ground connection. I moved
up to a receptacle on the outside of the house on the same line, again no
ground connection. Inside the garage, no ground connection. I opened the
circuit breaker box and checked the ground wire, it is good.
So, in my attic between the CB box and the garage there must be a
connection box where the ground has opened up.
Followup tomorrow evening.

** FYI:

GFCIs work independently of the safety ground in a 3 wire system - so will
still trip if a few mA of current is passing to any local ground like soil,
wet concrete or metal plumbing.

However, a missing safety earth conductor is never good as the metal cases
of 3 wire appliances can become live and nothing blows.

BTW:

I have not seen a 3 wire, hand held drill in quite a while.

**You got that right. My old man gave me my first electric drill (an
Hitachi, which I still use) back in 1967. It was a double insulated
type. He gave me my second electric drill (a variable speed Bosch in
1974 - which simply refuses to stop working). Also double insulated. He
kept using his aluminium cased Black & Decker for some reason. I have
not seen an earthed portable electric drill since at least that time,
though the old man's B&D is still in the family garage. It hasn't been
used in more than 20 years. Nor should it be. Terrifying things. Moreso
for those of us in 220-240VAC countries.


--
Trevor Wilson www.rageaudio.com.au

On Sat, 3 May 2014, Trevor Wilson wrote:

On 3/05/2014 12:01 PM, Phil Allison wrote:
"amdx"
could have saved my life.

I was in my workshed which is about 60 ft from the house drilling some
aluminum. I got a faint tingle in my hand, I touched the case of my
drill a couple times and didn't feel any thing, so I started to drill
again. I noticed the tingle again, I went through this a few times until I
decided there's a problem. The tingle was at a tiny red spot on my finger,
I later removed a small metalic sliver. If not for the sliver I probably
would not have noticed the missing ground, for I don't know how long.
The drill motor is a 3 wire system, hot, neutral and ground. I had it
plugged into a GFCI. I unplugged the drill and pushed the test button.
The GFCI didn't pop. I retrieved my DVM and tested from the drill case the
the dirt outside the door, it was about 80v. I then tested from the Hot to
the ground at the receptacle, that was about 20 v. I moved to another
Receptacle closer to the house, same thing no ground connection. I moved
up to a receptacle on the outside of the house on the same line, again no
ground connection. Inside the garage, no ground connection. I opened the
circuit breaker box and checked the ground wire, it is good.
So, in my attic between the CB box and the garage there must be a
connection box where the ground has opened up.
Followup tomorrow evening.

** FYI:

GFCIs work independently of the safety ground in a 3 wire system - so will
still trip if a few mA of current is passing to any local ground like soil,
wet concrete or metal plumbing.

However, a missing safety earth conductor is never good as the metal cases
of 3 wire appliances can become live and nothing blows.

BTW:

I have not seen a 3 wire, hand held drill in quite a while.

**You got that right. My old man gave me my first electric drill (an Hitachi,
which I still use) back in 1967. It was a double insulated type. He gave me
my second electric drill (a variable speed Bosch in 1974 - which simply
refuses to stop working). Also double insulated. He kept using his aluminium
cased Black & Decker for some reason. I have not seen an earthed portable
electric drill since at least that time, though the old man's B&D is still in
the family garage. It hasn't been used in more than 20 years. Nor should it
be. Terrifying things. Moreso for those of us in 220-240VAC countries.

That's odd. My Black & Decker from 1975 (variable speed, but only one
direction) has a three prong plug, still works fine, though about 25 years
ago I had to put in replacement brushes.

In about the past five years, I bought another B&D drill at a garage sale
for a few dollars, that one maybe has two prongs, but the B&D drill that I
found in the garbage when the students moved out (which does reverse) is
three pronged.

Even that fancy detail sander I found last year, only to realize when I
got it home that it was a 220V unit, that has three prongs, of the
non-North American kind.

Of course, now one has the option of getting a cordless drill, which is
certainly a whole lot safer, and beats getting out an extension cord or
two to bring power to that distant location that requires a drill. I
don't use mine that much, but the first time I had to drill a hole and
didn't have to lay out the extension cord paid for that cheap cordless
drill.

Michael

"Michael Black"

Phil Allison wrote:

I have not seen a 3 wire, hand held drill in quite a while.


That's odd. My Black & Decker from 1975 (variable speed, but only one
direction) has a three prong plug, still works fine, though about 25 years
ago I had to put in replacement brushes.


** A double insulated or "class 2" appliance may have a 3
pronged plug.

Egs, my Black & Decker 1600W heat gun and Atlas Copco
drill have 3 pin plugs but are clearly labelled "class 2" .

The AC cords have only two conductors.



In about the past five years, I bought another B&D drill at a garage sale
for a few dollars, that one maybe has two prongs, but the B&D drill that I
found in the garbage when the students moved out (which does reverse) is
three pronged.

** See above - look for the double square symbol.


Of course, now one has the option of getting a cordless drill, which is
certainly a whole lot safer,

** Well yes and no...

If you need to drill into walls it is possible to penetrate an AC
power cable and have the drill become electrified. Typically
the drill bit, chuck and metal cased gear box will be live -
the Atlas Copco drill has a plastic coating all over the chuck
and the drill body for this reason as do most modern units.



..... Phil

Phil Allison wrote on 3/05/2014 :
"Michael Black"

Phil Allison wrote:

I have not seen a 3 wire, hand held drill in quite a while.


That's odd. My Black & Decker from 1975 (variable speed, but only one
direction) has a three prong plug, still works fine, though about 25 years
ago I had to put in replacement brushes.


** A double insulated or "class 2" appliance may have a 3
pronged plug.

Egs, my Black & Decker 1600W heat gun and Atlas Copco
drill have 3 pin plugs but are clearly labelled "class 2" .

The AC cords have only two conductors.

For a time in Aus there were sockets with shutters opened by the ground
pin.
I think they are still standard in the UK.


In about the past five years, I bought another B&D drill at a garage sale
for a few dollars, that one maybe has two prongs, but the B&D drill that I
found in the garbage when the students moved out (which does reverse) is
three pronged.

** See above - look for the double square symbol.


Of course, now one has the option of getting a cordless drill, which is
certainly a whole lot safer,

** Well yes and no...

If you need to drill into walls it is possible to penetrate an AC
power cable and have the drill become electrified. Typically
the drill bit, chuck and metal cased gear box will be live -
the Atlas Copco drill has a plastic coating all over the chuck
and the drill body for this reason as do most modern units.



.... Phil

--
John G

On 3/05/2014 3:33 PM, Phil Allison wrote:
"Michael Black"

Phil Allison wrote:

I have not seen a 3 wire, hand held drill in quite a while.


That's odd. My Black & Decker from 1975 (variable speed, but only one
direction) has a three prong plug, still works fine, though about 25 years
ago I had to put in replacement brushes.


** A double insulated or "class 2" appliance may have a 3
pronged plug.

**Correct. Both my Hitachi and the Bosch use 3 pin plugs. The earth wire
is not used.


Egs, my Black & Decker 1600W heat gun and Atlas Copco
drill have 3 pin plugs but are clearly labelled "class 2" .

The AC cords have only two conductors.



In about the past five years, I bought another B&D drill at a garage sale
for a few dollars, that one maybe has two prongs, but the B&D drill that I
found in the garbage when the students moved out (which does reverse) is
three pronged.

** See above - look for the double square symbol.


Of course, now one has the option of getting a cordless drill, which is
certainly a whole lot safer,

** Well yes and no...

If you need to drill into walls it is possible to penetrate an AC
power cable and have the drill become electrified. Typically
the drill bit, chuck and metal cased gear box will be live -
the Atlas Copco drill has a plastic coating all over the chuck
and the drill body for this reason as do most modern units.

**I got a story about that too. A few years back I decided to replace
the incandescent fitting in part of my workshop with a double 37 Watt
fluoro fitting. As luck would have it, the wiring was installed in the
ceiling at the same time the slab was poured. I drilled a mounting hole
into the concrete ceiling............ You guessed it. Straight into the
conduit and into the wiring. Had to use surface mount conduit and
re-wire the whole bloody lot. GRRRR.

Yeah, I know. Shoulda used one of those wiring detector thingys.


--
Trevor Wilson www.rageaudio.com.au

On 5/2/2014 9:01 PM, Phil Allison wrote:
"amdx"
could have saved my life.

I was in my workshed which is about 60 ft from the house drilling some
aluminum. I got a faint tingle in my hand, I touched the case of my
drill a couple times and didn't feel any thing, so I started to drill
again. I noticed the tingle again, I went through this a few times until I
decided there's a problem. The tingle was at a tiny red spot on my finger,
I later removed a small metalic sliver. If not for the sliver I probably
would not have noticed the missing ground, for I don't know how long.
The drill motor is a 3 wire system, hot, neutral and ground. I had it
plugged into a GFCI. I unplugged the drill and pushed the test button.
The GFCI didn't pop. I retrieved my DVM and tested from the drill case the
the dirt outside the door, it was about 80v. I then tested from the Hot to
the ground at the receptacle, that was about 20 v. I moved to another
Receptacle closer to the house, same thing no ground connection. I moved
up to a receptacle on the outside of the house on the same line, again no
ground connection. Inside the garage, no ground connection. I opened the
circuit breaker box and checked the ground wire, it is good.
So, in my attic between the CB box and the garage there must be a
connection box where the ground has opened up.
Followup tomorrow evening.

** FYI
GFCIs work independently of the safety ground in a 3 wire system - so will
still trip if a few mA of current is passing to any local ground like soil,
wet concrete or metal plumbing.

Yes, good reminder, I knew it was a difference between the hot and
neutral, but when I was missing ground my mind went elsewhere.


However, a missing safety earth conductor is never good as the metal cases
of 3 wire appliances can become live and nothing blows.

BTW:

I have not seen a 3 wire, hand held drill in quite a while.


... Phil

It is old, scares me now!
Mikek



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On Fri, 02 May 2014 20:30:04 -0500, amdx wrote:

So, in my attic between the CB box and the garage there must be a
connection box where the ground has opened up.

http://www.amazon.com/Electrical-Receptacle-Outlet-Ground-Tester/dp/B0012DHVQ0
Buy one (or two) and walk it around to every outlet in the house. Also
check power strips which I've seen miswired.

Followup tomorrow evening.

The life you save may be your own.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

amdx wrote:


I was in my workshed which is about 60 ft from the house drilling some
aluminum. I got a faint tingle in my hand, I touched the case of my
drill a couple times and didn't feel any thing, so I started to drill
again. I noticed the tingle again, I went through this a few times until
I decided there's a problem. The tingle was at a tiny red spot on my
finger, I later removed a small metalic sliver. If not for the sliver I
probably would not have noticed the missing ground, for I don't know how
long.

Depending on the grounding arrangements, this can sometimes still happen
even if there isn't a complete disconnection or any serious leakage
current.

The sensation of electrical shock is entirely dependent on the current
density in the susceptible tissues, rather than the voltage applied.
Human tissues are very conductive, but dry skin usually acts as a
partial insulator so low voltages don't create enough current to cause
any sensation.

With a sliver of metal puncturing the skin and leading directly into the
underlying tissue, probably quite close to nerve endings, a very low
voltage would develop enough current to be easily detectable. Tests
have suggested that A.C. voltages below the 2v level can be detected by
the tongue when the feet are in a wet, conductive environment.

This is a particular problem where the neutral and earth conductors are
bonded ("P.M.E." in the UK) because the small voltage dropped along the
neutral will apear on any bonded "earthed" metalwork. In farms and
other wet environments, this can lead to animals receiving shocks from
licking handrails, feeding troughs - and from milking machines through
the milk lines directly to their teats.


--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk