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Primary power requirements for ForceCut units



SpyGuy
02-15-2010, 10:42 PM
I am interested in the ForceCut LP line of plasma cutters. For primary power, do these ForceCut units use 2-wire 230VAC power (2 hots + ground) or 3-wire 230VAC power (2 hots + neutral + ground)?

KHK
02-16-2010, 08:23 AM
Two Hots and a GROUND is requited. There is a ground lug on the rear of the machine, it is used if you get HF noise.

SpyGuy
02-16-2010, 01:27 PM
Two Hots and a neutrial is requited. There is a ground lug on the rear of the machine, it is used if you get HF noise.

I don't have any Longevity machines and I'm still waiting for a definitive answer from the company. But with all due respect, I suspect your answer is incorrect. I can't imagine that any of the welders or plasma cutters are designed to operate without a full-time ground connection. And a neutral is only required if the machine needs 115VAC from the primary.

I'm farily certain all the 230VAC machines require at least 2 hots + ground. My question is, do they also need a neutral (e.g., for some internal control circuit that requires 115VAC)?

KHK
02-16-2010, 03:36 PM
Two Hots and a (GROUND) is requited. There is a ground lug on the rear of the machine, it is used if you get HF noise.

There are three wires on the line cord from the welder. Black, white and green or green black stripe. The black and white are the power input wires for 240vac. The green is the ground, it is actualy connected to the welders chassie. The reasion that I encluded the quote is that I changed the word neutral to ground. Sorry!

SpyGuy
02-16-2010, 03:48 PM
Two Hots and a neutrial(Ground) is requited. There is a ground lug on the rear of the machine, it is used if you get HF noise.

You already corrected yourself, but your original post may still be confusing to some as you put "neutrial(Ground)" together. Just to be clear, neutral is NOT the same as ground, even though they are tied together at the service entrance.

A neutral conductor is a current carrying conductor: the exact same amount of current that is flowing through your 115VAC hot is also flowing though your neutral (excepting multiwire branch circuits, but that's beyond the level of this discussion). In fact that is how a GFCI works: it compares the current flowing through the hot and neutral lines. If the current is balanced ("out" = "in") then the load is safe. But if not balanced, that means that current is leaking to ground somewhere (and maybe NOT to the ground terminal in the GFCI). For example, it could be leaking through your body and into the bathtub drain pipe. So if the GFCI senses this imbalance between hot and neutral (even if there is NO current entering the GFCI's ground terminal), then the GFCI will almost instantly open and hopefully save your life.

A ground wire (the correct name is: "Equipment Grounding Conductor" or "EGC") should never carry current except in a ground fault situation (at which point it should cause the circuit breaker on the faulted branch circuit to immediately trip).

NOTE: This is a repeat of a post in my WeldAll power requirements thread. But because someone could kill themselves if they read incorrect electrical advice, I'd rather err on the side of safety and make sure the correct information is posted in both threads.