Circuit protection (was: RE: Latest addition : PDP 11/70)

From: Steve Robertson <steven_j_robertson_at_hotmail.com>
Date: Wed Aug 1 14:46:51 2001

>Certainly in the US. Typical branch circuits are 15 or 20A at a nominal
>115V (although voltages between 110 and 130 are common, largely as a
>function of how the single phase was derived). The NEC doesn't >consider
>the fact that a given appliance that's plugged into such a >branch circuit
>may have an attached cord that is rated at less that >the rating of the
>branch to be an issue; it simply requires that in >the absence of a
>overcurrent that the rating of the cord match be >appropriate for the
>current draw of the appliance.

You sure about that?

>From what I understand, every conductor must be capable of carrying a
current greater than the breaker that protects it. Otherwise, the cord would
be the first thing thing to fail in a overcurrent situation. This would
present a very significant fire danger.

Even the cheapest kitchen appliances have fairly heavy power cords. It's not
because they draw a lot of current or the manufacturers are generous, it's
because the fuses / breakers in your kitchen have a higher amperage rating
than in other places in the home. So, those appliances must have heavier
cords to offer protection.

SteveRob

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Received on Wed Aug 01 2001 - 14:46:51 BST

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