As how I was taught in the last NEC 2005 class I had a few weeks ago, it all
depends on the 'AHJ' or Authority Having Jurisdiction. If he says 3 wires,
then three wires it is. If four then four.
Mod-U-Lator,
Mike(y)
W3SLK
----- Original Message -----
From: <Gudguyham@aol.com>
To: <amps080605@w4zt.com>; <amps@contesting.com>
Sent: Tuesday, July 04, 2006 12:18 PM
Subject: Re: [Amps] Safety grounding - was Mains Isolation Transformer
In a message dated 7/4/2006 10:12:30 A.M. Eastern Standard Time,
amps080605@w4zt.com writes:
Lou, that wouldn't necessarily be true. If you had a 240 Volt device
that didn't have any 120 Volt needs at all, you would still HAVE to use
that plug to get the power from the generator. In that case, two
conductors would have zero current. You either put the correct 4 pin
plug on your three wire cord or make an adapter.
STRICTLY SPEAKING A DEVICE THAT REQUIRES NO NEUTRAL AND IS 240V WOULD ONLY
HAVE A 3 WIRE PLUG ON IT. YES, YOU ARE RIGHT, YOU WOULD HAVE TO MODIFY THE
PLUG ON THE DEVICE OR MAKE AN ADAPTOR, IN WHICH CASE YOU WOULD NOT USE A
NEUTRAL
WIRE, ONLY A BOND.
There are hundreds of thousands of 3 wire 240 Volt receptacles in use in
the USA today that are still legal until someone makes a wiring change
that requires an upgrade to meet code. Code changes don't mean that
existing wiring is illegal or unsafe. The change in code was to strictly
meet the need for handling both 240 Volt and 120 Volt loads from a
single receptacle and still provide the bonded safety ground. It has
nothing to do with what we really CAN do both safely and legally. Even
if you have a 4 wire receptacle, you can still use only 3 of them if
your load doesn't need the neutral for a 120 Volt current path. Leave it
off the plug or don't connect it in the device, it's all the same.
73, Tony W4ZT
TONY, WE ARE SAYING THE SAME THING, HOWEVER IF ONE WAS CONFRONTED WITH SUCH
A SITUATION AND DECIDED TO USE A CABLE WITH 4 WIRES AND THEN ON ONE END
CONNECTED THE NEUTRAL TO THE BOND, THAT WOULD BE A VIOLATION. BEST TO USE
3 WIRES
AND LEAVE ONE CONNECTION ON THE GENERATOR END (NEUTRAL) NOT CONNECTED.
YEARS
AGO WHEN OVENS WERE STRICTLY 240V A 3 WIRE SYSTEM WAS USED, THEN LATER ON
WHEN THEY ADDED CLOCKS AND TIMERS WHICH USED 120V, THEY GROUNDED THE 120V
DEVICE
TO GET THE 120V NEEDED. THE PROBLEM CAME WHEN POOR CONNECTIONS ON BX CABLE
THAT WERE ONLY HELD WITH HICKEY FITTINGS OR THE LIKE GOT LOOSE OR CORROSION
ON IT AND DUE TO THE FACT IT WAS CARRYING CURRENT WOULD SPARK AND CAUSE
FIRES. CODES USUALLY CHANGE BECAUSE OF SOME SAFETY ISSUE HOWEVER REMOTE.
LOU
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