RE: [CAD_CAM_EDM_DRO] Variable Transformer

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Isolation transformers reduce the available current in accidental
across the line contact. Fuses and circuit breakers are too slow to
protect against injury. They are required in medical applications
by the NEC . Many educational and industrial facilities will
include this in their site regulations. Some cities my also.

1.1 These requirements cover isolated power systems equipment rated
600 Vac or less, intended for installation and use in nonhazardous
areas in health care facilities in accordance with the requirements
in Article 517 of the National Electrical Code, NFPA 70, and in the
Standard for Health Care Facilities, NFPA 99

see for a lot more.
http://www.iaei.org/magazine/02_f/johnston.htm

Auto transformers allow accidental straight across the line contact
even when a low voltage is set up.

Ground fault interrupters provide some additional protection but
not straight across the line protection.


Not an EE.

jesse