10 ga wiring question

[Professor Marvel]

I will try to accurately express my question.
I have a 4 (red, white, black, ground)wire connection to a 30 amp breaker to tie my generator to my house. Weatherproof outside box designed for a generator connection.
I recently bought a Hobart mvp 210 welder which is a 120/240 v welder. It tells me in the manual that for the 220 side I only need 14ga wire but I want to use 10 ga. This question is only about the 220 side.
I would like to use this same connection to power my welder. The welder has a 3 wire connection.
I want to make an extension/transition cord from 10 ga wire with 3 wires (white, black, g) (ok I am using 10/2 romex) to connect my welder to my circuit.
My question is --- what do I do with the ground connection I have at the weatherproof box at the house since I only have 3 wires? Tie nothing to it or jump it to the lug that would have been common?
Basically I have a 3 lug (prong)plug at the welder end and a 4 lug (prong) at the supply end with romex with 3 wires in it and I want it to be safe. I already assume I should probably not make an extension cord from romex buy it is my cheapest choice.

 

[George2615]

I assume you are going to plug the welder into the existing 4 prong receptacle for the generator. If so, you only need to hook up the three 10 ga. wires in your 4 wire male plug. Two hot wires and a ground. Leave the 4 terminal blank.

 

[Professor Marvel]

Thank you that is what I wanted to know.

 

[Rocky Hoffler]

the fourth wire is a bond wire same electrically as a ground basically a safety feature if ground was to broken

 

[hosspuller]

is this "generator box" a proper transfer switchbox? Or is it a rag-tag mish-mash jack-leg "electrician" backfeed box ?

If proper, it won't work since the transfer switch disconnects it when utility power is present.

 

[Professor Marvel]

It came with the generator but it has no transfer switch capabilities. I believe it is called a 30 Amp power inlet box. It is just a weatherproof box with a 30 amp plug in connection. I have to kill the main breaker myself before I use it with the generator.

 

[KennyG]

Unless I'm missing something, you intend to use 10/2 romex for a 220 v circuit. You can't do that. You would need 10/3. You can't use the bare wire in the 10/2 as the common. Granted, it isn't the current carrier in a 220 circuit, but that isn't what it's for. Use 10/3 wire.

Also, you may already have the romex and I will admit to using romex for a quick extension cord, but if you intend to use this much, buy a length of SOOW or SJOOW wire and fab up the extension cord. I will be much easier to use and will actually be designed for extension cord use. You can find various lengths on ebay at reasonable prices.

 

[Professor Marvel]

If I find myself using it much I will certainly switch to an SJ type of cord
just want to get by safely for now
the wire called for by the Hobart manual is 14/2 from the breaker box to the outlet. The plug on the welder only has 3 lugs.
Apparently this is a smaller mig with low amperage requirements.
Romex is a PIA wire to use as an extension cord because it is too rigid.

 

[SimS]

Professor;

You're smart to up size the wire size on the breaker to the outlet. 14 gauge wire is generally used in 15 amp circuits. I'm betting that the welder needs more than 15 amp input. Good luck.

SimS

 

[Professor Marvel]

It's kinda funny.
The welder manual calls for 14ga (for 220v use), the 220v plug that comes with the welder has a 50 amp configuration (I think so that it will plug into a normal buzz box outlet) and I want to use 10ga. I feel odd about the inconsistency of the components.

 

[LD1]

Welders are allowed to use under sized wire given the duty cycle. They arent drawing current constantly.

Sizing wires is all based on how hot the wire is going to get. And using a welder, even undersized wire isnt going to get that hot based on the time it is used in a given hour.

From my understanding (Im no certified electrician), but 220v circuits (if there are also 110v circuits involved) require 4 wire setup. Like a range, or dryer, which has heating elements that operate off of 220v, but control circuits that run off of 110. Those need 4 wire. For loads that are 220v only, like shop equipment, air compressor, water heaters, etc. Only 3 wires is required. 2-hot and 1 ground.

So if you use the romex, 10-2 will certainly work for temporary cord. But going to 10-3 SO cord will be better long term.

Also, When talking about romex and 10-2 and 10-3, the 2 and 3 are the number of current carrying conductors. Not the total numberof wires. So 10-2 romex will have a black, white, and a bare ground. With SO or SJ cord, You would need 10-3 to get the proper number of wires. Since the ground in them is insulated and not bare, it is counted when talking about 10-2 and 10-3.

 

[Professor Marvel]

Thanks for the explanation LD. I know how many wires are in each just because I counted them over the years but I did not understand why.
Not sure how this welder does the transition from 120-240 but I have to plug it into a 120v outlet to use the 120 side and I have to plug it into a 240 v outlet to use the 240 side. It has 2 different ends to stick on the wire and it knows what it is plugged into. And they are both 3 prong plugs.