Seth Rothenberg via EV wrote:
I bought a dryer replacement cord with a 3-prong plug and a matching
socket (10-30R)... it says "3-pole, 3-wire, non-grounding"... Is this
an appropriate combination to feed the 6kw charger on my Leaf, using
the OpenEVSE?
I don't know about your openEVSE, but this 3-wire cord isn't going to
work with things that have or need a GFCI (Ground Fault circuit
Interrupter). For instance, my Avcon EVSI has an internal GFCI and needs
a 4-wire cord with separate neutral and ground.
Background: The standards for home electric ranges and clothes dryers
were written back in the 1940's when appliances were not grounded. They
needed 240vac for their heating elements, but also 120vac for things
like oven lights and clock motors. So they had 3-wire connections; two
hots with 240vac between them; and neutral with 120vac between it and
either hot wire.
This turned out to be unsafe. It was easy to for a short to occur in the
appliance that connected its case to one of the hot wires. Touch the
metal faucet on a sink and the case of the appliance and you got
electrocuted!
The safety agencies wanted the case to be grounded. But industry lobbied
hard to "grandfather in" the 3-wire plug and cord set. The compromise
was to use the 3rd wire for *both* neutral and ground. This is what you
got... an old "legacy" 3-wire cord and plug. It's for an old dryer that
grounds the case to the neutral.
> Is there something more appropriate for a GFCI-protected 30 amp 220
> circuit?
The standards were finally changed in 1996 to require a 4-wire plug,
with two hots, and separate ground and neutral wires. These are the NEMA
14-30 and 14-50 now required for new installations. They're used for
clothes dryers, electric ranges, marine and RV parks, and now also for
charging EVs etc.
--
Knowledge is better than belief. Belief is when someone else does
your thinking. -- anonymous
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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