Circular saw won't ground, safe?

[spudnuty]

It is quite an easy matter to replace the power cord and ground but
even with a grounded device you're depending on a chain of secure
grounds to keep your tool safe. I would also obtain a GFCI pigtail and
only run your power tools from that. They're required on all jobsites
I've been on and all the electrocutions I've studied have been from
workmen bypassing them.
Richard

 

[Dr. Anton T. Squeegee]

In article <1116159867.dda65d992f7a2135aa9763b69aaf9081@bubbanews>,
bravecat@gmail.com says...

Is it safe to operate an all alloy housing circular saw. My
15-year old industrial saw is reliable but the only thing aging
is the cord. The cord's insulation is cracking and deteriorating.
Last I'd check the ground wire is open but hidden from view.
What would be the hazards if I continue to use it?

You would be risking a fatal electrical shock, should the saw
develop an internal insulation fault (as it very well could if it's that
old).

Replace the cord completely. If you lack the requisite skill
and/or tools to do so properly, you should take the unit to a
professional repair shop. Any place that repairs power tools should be
able to handle it.


--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute.
(Known to some as Bruce Lane, ARS KC7GR,
kyrrin (a/t) bluefeathertech[d=o=t]calm -- www.bluefeathertech.com
"If Salvador Dali had owned a computer, would it have been equipped
with surreal ports?"

 

I think the OP was trolling, judging by his lack of response. It looks
like he hauled in a whole netfull.

Bob

 

[spudnuty]

I always double and triple check everything including a final check
with a non contact voltage tester. I've seen so many wierd things
working on clients electrical setups. You know the "What in the
F......" moment and its another one for the books.
This sounds like a pertinent case:
http://www.cdc.gov/niosh/face/stateface/wi/93wi214.html
"A 45-year-old male electrician (the victim) was electrocuted when he
contacted an energized ˝-inch metal-cased electric drill.... There were
puddles of water on the cement floor of the work site. The drill was
connected to a temporary power pole by a series of three extension
cords, two of which were missing the ground pin.... The cords were
plugged into a ground fault circuit interrupter (GFCI) receptacle
mounted on the power pole. ... However, testing after the incident
disclosed the GFCI was inoperative, and the fuse box for the 120 volt
single phase 15- and 20-ampere receptacle outlets located at the power
pole contained two 40-ampere fuses."

Richard

 

[Don Kelly]

"Robatoy" <design@BULLtopworks.ca> wrote in message
news:design-E86876.18202715052005@news.bellglobal.com...

In article <b7Lhe.272$Ye3.210@news02.roc.ny>,
"toller" <toller@yahoo.com> wrote:

don't remember the exact numbers, but seems like it was around the
90-100
milliamp range that was lethal due to causing fibrillation.

You are correct; 100ma is about the lethal threashold. But it is
difficult
to get 100ma off 120v unless you are in saltwater.
Naturally adverse medical conditions, or just plain bad luck, will
change
everything!

Where do you get this ? You state this stuff as fact? Do you have ANY
idea how irresponsible you are?

Shame on you!
-------

Actually, such information is available many places, including the EPRI book
on EHV power lines. The 100ma level is about the 0.5% probability level for
fibrillation. However, fibrillation is time dependent so that on prolonged
contact, the level drops (i.e. at a let-go current of 9-10ma it takes about
10 minutes to cause fibrillation). In many cases, design is based on a 5ma
level which is considered at or below the let-go level (not painless) for
both adults and children.
--
Don Kelly
dhky@peeshaw.ca
remove the urine to answer

 

[Don Klipstein]

In <b7Lhe.272$Ye3.210@news02.roc.ny>,"toller" <toller@yahoo.com> wrote:

don't remember the exact numbers, but seems like it was around the 90-100
milliamp range that was lethal due to causing fibrillation.

You are correct; 100ma is about the lethal threashold. But it is difficult
to get 100ma off 120v unless you are in saltwater.
Naturally adverse medical conditions, or just plain bad luck, will change
everything!

A few problems with this:

1. Perspiration is salty. A sweaty hand on a metal power tool could have
resistance down to about 1k ohms or so.

2. Electric shock can stimulate sweat glands.

3. Electric shock at a few 10's of mA or maybe around 10 mA can stimulate
muscles and cause you to involuntarily grip what is shocking you.

4. Most sources say 100-1,000 mA is a range of current that is likely to
cause ventricular fibrillation, with a few saying this deadly range
starts at 50 mA. (Also a few sources make the upper limit of this
"most deadly range" lower.)
The changes of death do not decrease to zero at 99 or 49 mA. I have
heard of electrocution by 30 mA from a neon sign transformer, although
people *usually* survive this.

5. Electrocution is unreliable. With electric chairs, they use enough
current to either:

* Cook vital organs
* Paralyze breathing muscles long enough to deprive the brain of
oxygen to the point that breathing will not restart when the
shock ends

Lack of electrocution is simularly unreliable.

6. The low fatality rate of 110-120V shocks lulls people into a false
sense of security that leads to this voltage achieving a body count.
On US Navy ships, most power circuits are 440V rather than 110V, and
most electrocution deaths are from 110V. (Another factor could be
that lights and ordinary outlets - where exposure to less-trained
people is greater than that of 440V stuff - are 110V.) (Yes, US
Navy ships have 110V at least nominally rather than 120V.)

- Don Klipstein (don@misty.com)

 

[Don Klipstein]

In article <M6Qhe.622$W51.5387@typhoon.sonic.net>, Don Bruder wrote:

In article <jf5f815dvec9nr4h41ro19p3034elev1lq@4ax.com>,
LRod <duckecho@gmail.com> wrote:

Neither of you are (the only one). I do, too. It's too easy to check,
and the potential consequences of not checking are too high.

Absolutely. The exact same concept applies to guns: "If there's even the
slightest doubt about whether it could be loaded, then *IT IS* until
proven otherwise."

If there's even the slightest doubt that a pair of wires might be hot,
then *THEY ARE* until proven otherwise.

Any other assumption in either case is stupidity on a scale you only
read newspaper articles about. Usually articles ending "Services will be
provided by <insert name> funeral home."

I have been told there are old pilots and bold pilots, but not many who
were both. My father said the same thing about electricians.

- Don Klipstein (don@misty.com)

 

[spudnuty]

For info on how a GFCI works check Sam's , very complete:

http://www.codecheck.com/gfci_principal.htm

please explain why do some modern factory drills, grinders
and saws get away without a ground plug?

As above double insulated and more over usually GFCI protected.

a hot or neutral short to ground shuts down my entire electrical
system. Is this the GFCI?

Hot to ground short - how big is the spark? 15-20 Amps? Breaker. No
spark? - Possibly a GFCI
Neutral to ground short - Possibly a GFCI or total miswire
And if this is the case can't you ID the GFCI?

Incidently any electrician knows that you can be shocked from a neutral
line, especially if you're dissasembling a junction of several neutrals
even with the power turned off to the box you're in. One or more of the
neutrals can be tied back to another hot or often the other leg through
an appliance. Can be a nasty suprise if someone turns on the toaster
while you're working on a neutral. There could also be a break in the
neutral.
I recently rewired a garage where the BX was run along the ground
right under the threshold of the door. Salt corrosion rotted the
neutral wire out as well as the BX shield. Whoever did this job also
tied the neutral to conduit ground so the path was hot to device
neutral to box ground to earth through the remenents of the BX. Their
son got a nasty shock walking into the garage barefoot on a rainy night
and turning on the light!

Richard

 

[Robatoy]

In article <uHRhe.291$Lv3.52@news02.roc.ny>,
"toller" <toller@yahoo.com> wrote:

Any electrical book. Ever read one?

As a matter of fact I did. Many. And I have a piece of paper to prove it.
I went straight from college into a career at Ontario Hydro (the
province-wide power company) in operations.
During my tenure in operations at a 2000 MW power-station, I received an
award for identifying safety problems relating to test procedures in
station service electrical distribution. Again, paper/plaque and
pictures from a dinner in my honour to prove it.
But that's enough about me.

How about you? If you ever DID read anything about electrical
engineering, you must now read some material on interpretative skills
and memory retention, because, buddy, you do not know what you are
talking about.