Damage to the screwdriver isn't a total disaster; melting the ring in situ
can spoil your day. Don't wear jewelry while working on anything hot, even
low voltage. And with HV it's best to follow the orders we had as Navy RT's
back in WW2: When a transmitter needed attention inside: 1. Disconnect and
lock/tag the disconnect switch. 2. Check interlocks. 3. Take the
insulated ground stick and hold onto every possible contact. 4. repeat (3)
with special attention to anything looking like a condenser (capacitors
hadn't been invented yet.)
Then get to work with thinking and ohmmeter. And still work as if the power
was still on.
A ham is far above the CB'er who is forbidden inside the case - he should be
able to do many repairs even on more complicated equipment. Especially with
T-T, where an in-country phone call gets an engineer or tech who can
practically walk you through any repair that can be done outside of
Tennessee. But where high-voltage circuits are involved, work them cold,
with lower voltages use well-insulated meter probes. 12 volts isn't
dangerous unless it's given a low-impedance path to ground but above about
100 v can really hurt. K3TX
----- Original Message -----
From: "Pumbaa" <pinkertontommrs@bellsouth.net>
To: <geraldj@weather.net>; "Discussion of Ten-Tec Equipment"
<tentec@contesting.com>
Cc: <collins@mailman.qth.net>
Sent: Thursday, February 18, 2010 7:57 PM
Subject: Re: [TenTec] Electric safety
> Thanks for the safety tips. I am sure the ALS-1300 at 50V and a peak of
> 50
> amps could melt a screwdriver or a gold ring. Would wearing latex exam
> gloves offer any extra protection when working on a radio?
>
> Tom AG8K
>
> ----- Original Message -----
> From: "Dr. Gerald N. Johnson" <geraldj@weather.net>
> To: <tentec@contesting.com>
> Cc: <collins@mailman.qth.net>
> Sent: Thursday, February 18, 2010 5:25 PM
> Subject: Re: [TenTec] Electric safety
>
>
>> On Thu, 2010-02-18 at 16:05 -0600, Pumbaa wrote:
>>> That is one thing (HV) I did consider when I decided to buy the
>>> Ameritron
>>> ALS-1300 Solid State Amplifier. The other is the lack of used Centurion
>>> amps for sale.
>>>
>>> Tom AG8K
>>>
>> While the mark left by high voltage may be small, a low voltage supply
>> can cause amputations, especially a lead acid battery. 12 volts at a 100
>> amps through a wedding ring can amputate that finger cleanly. That much
>> current through a metal watch band can do a lot of damage too.
>>
>> For that matter when shock is involved, the "ordinary" 120 volt circuit
>> is more deadly than high voltage in most situations. That's because high
>> currents stop the heart, then when you fall down the bump is a pretty
>> good heart starter. But 120 volt shocks often put the heart into
>> fibrillation, and in that operating mode the heart's reflexes are
>> satisfied though it pumps no blood. 4 or 5 minutes and you're brain
>> dead. A few more and your dead all over. You can only be brought of
>> fibrillation with a defibrillator to give a massive short shock to stop
>> the heart and let it bounce into a normal rhythm again.
>>
>> True, the burns from a 7 KV power line are bad but I had several clients
>> who survived those and several families of those shocked by tools
>> supplied with 120 volts that didn't survive. And I had to explain why in
>> my consulting business over the past several decades.
>>
>> High current and any voltage demand some attention and care. Even if the
>> shock isn't severe enough to cause major injury or heart problems the
>> speed with which the shock can cause your arm muscles to contract and
>> you to extract your hand from the radio can cause the back of your hand
>> to loose much skin as it hits stuff on the way out of the radio.
>>
>> Good safety rules require no watches or rings when working with live
>> electricity at any voltage. Good safety rules require you to not work on
>> high voltage apparatus with the power on, and after the power is off AND
>> thoroughly disconnected in a way that NO ONE can apply power (like pull
>> the plug and put it IN your pocket) short the power supply with a metal
>> rod on an insulating handle, and park it there until you are finished
>> with the work. E.g. short it and keep it shorted. And there's the old
>> rule, one hand in pocket, one hand in circuit. That minimizes the
>> current paths through the heart, but you can still jump fast and high
>> without control and the bounces can get you into deep trouble, like
>> landing ten feet from the foot of the ladder you were on.
>>
>> 73, Jerry, K0CQ
>>
>> _______________________________________________
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>> TenTec@contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>
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