>
>Paul Christensen wrote:
>>
>>Now, if the neutral is lost for any reason, the chassis will not be hot
>>through the blower winding. If allowed to continue in this condition, I
>>suspect that the blower would continue to run by finding its neutral return
>>through the BNC, SO-239, or RCA jacks and potentially complete the path back
>>to neutral via the ground lead on another piece of equipment.
>
>There are two sides to separating neutral from ground. One is in the
>mains supply and cable, but the other is in the equipment. The rule is
>that "neutral is only for power", and "ground is only for grounding".
>Therefore all 115V power supplies - including the blower and everything
>- must return through neutral.
>
>To check, you should be able to find no continuity and good insulation
>between neutral and chassis at the power input to the equipment.
>
>However, because of the historical confusion between these two different
>conductors in the USA, there have been published examples of 4-conductor
>circuits where they get it wrong.
>
>It's easier to understand this in Europe where there is only one 230V
>phase to think about. Here, "neutral is only for power", and "ground is
>only for grounding" has been SOP for generations. Most home
>installations have a circuit breaker which will trip if all the line
>current doesn't return through neutral.
Ground fault interupter breakers are known to be unreliable in strong RF
fields.
>As little as 30mA not returning
>through neutral (maybe because it's flowing through a person to ground)
>will trip the breaker.
>
? GFI breakers should not be used with electric chairs.
cheers
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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