[Jewelry making - Article 00062] - Re: [Orchid] Anodzing Power Supply

[James Binnion]

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>>      [...] if you take a voltmeter and  touch one probe to a grounded
>>      surface and one probe to a hot lead you will read the line voltage.
>>      If you you were to be unfortunate enough to touch both a grounded
>>      surface and the hot lead you would be shocked and possibly killed.

>     Agreed. When anodising niobium and titanium we are exposed to both
>     leads, the anode and (throught the electrolyte) the cathode. I
>     imagine that an isolator would be less than perfect an a safety
>     device for anodising as the danger we face is not so much
>     line-to-ground as line-to-neutral.

    Not so, the danger is that you are surrounded by grounded objects
    basically everything in our environment is at ground potential. All
    objects have varying ability to conduct electricity even insulators
    such as plastics can become conductors when dirty or wet or both. So
    the potential to make a connection to ground via a conducting item
    in a normal studio environment is great so the likelihood of
    receiving a shock is fairly high if you are using a non isolated
    power supply. If you use the isolated variety then you must make
    contact with both leads at the same time which is less likely to
    happen by accident. 

>>      [...] The GFI - Ground Fault Interrupter, is also called Safety
>>      Switch, RCD - Residual Current Device, ELCB -Earth Leakage Circuit
>>      Breaker, Core Balance Relay and other names in different places.
>>      Before these devices were readily available, the isolation
>>      transformer was the only protective device available.  It is still
>>      widely used to work (repair) on circuits that have mains potential
>>      circuitry or to isolate test equipment earths to prevent short
>>      circuits when testing such circuitry.

>     Would you say then that a GFI (RDC etc) is VERY important in an
>     anodiser?

    Yes, the GFCI will act as a safety of the last resort if you manage
    to get a connection between ground and or the mains and the output
    of the isolated power supply  and  you become part of the circuit it
    may save your life. 

>>      [...] As a last point, you were to use a standard "non isolating"
>>      variac with GFI protection and contact something earthed (say when
>>      anodising), it is possible to trip the GFI.

>     Meaning it works as well as an isolation transformer?

    No, it is a last resort type of safety it may keep you from getting
    seriously hurt but if you manage to trip it by being part of the
    circuit you may still be hurt.  Isolation transformers and GFCI's
    are last resort safety devices they are not a substitute for proper
    safety practices when working with high voltages. Electricity will
    always follow the path of least resistance, it is critical to not
    place your body in that path. 

Jim Binnion

James Binnion Metal Arts
Phone (360) 756-6550
Toll Free (877) 408 7287
Fax (360) 756-2160
http://www.mokume-gane.com
jbin AT mokume-gane.com
Member of the Better Business Bureau

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