Thanks Ned, I received the e-mail.
I stopped by my local Home Depot this afternoon and they have a 100A breaker
in stock for my panel. My panel gives me 200A, so I don't see a problem
running this. They also have #2 Stranded THHN wire in stock. It was
actually the same price as the #4 THHN, so why not go with the #2. I
believe the #2 THHN wire is rated at 130A. So I will just run this wire
from my 100A breaker through some 1" conduit right to my welder, and then
hard wire it into my welder. I can just use the breaker switch to turn
everything off when not in use (vs. unplugging it from an outlet).
This might be an overkill, but at least I know that I will be able to use
maximum capacity of the welder based on everyone's feedback to this thread,
and I won't have to worry about burning down the house!
Let me know if this sounds good, or if I have overlooked anything important.
Thanks for all the info.
Looks like you've received the answers you were looking for. Sorry I didn't
get back to you in a timely fashion. Tough weekend for us with a lot to do
in our garden.
The only thing that you might want to discover is if you are required to
have a disconnect at the machine. Having the breaker serve as the only
disconnect may not be up to code, especially if you're running the wires
from one building to another, or the main panel is in a different room from
the welder. Even though my welder is only 30 feet across the room from
the main panel, I have used an old fused switch so I can kill power right at
the welder. The switch I am using is the old one that used to be the
disconnect for my first shop's 3 phase, 100 amp service. I'm using two
of the three poles only. Saved me from buying a new switch. I'm no
electrician, and don't claim to know code, but I seem to recall that machine
tools have such a requirement. Makes it safe to work on the welder
without someone turning on the circuit.
That's a good point. I will look into putting a switch near the welder. I
just have to figure out what type of switch can handle a 100A load, and be
fully enclosed. The fuse panel is on the outside of my garage wall, and the
welder is in the garage. This is not a shop, but just my 19x19 2 car
garage. No room for cars though!
I found the actual input requirements stamped on the welder, and it is 230v
at 106A. So using a 100A breaker and #2 THHN wire will actually be more
than enough to run the welder at full capacity.
Looking in my pocket ref under current capacities, it shows that single wire
in open air can handle the following capacities: 2 awg THHN can handle 190A
and 6 awg THHN can handle 105A. But in the section labeled '3 wires in a
cable', the #2 awg THHN can handle 130A and the 4 awg THHN can handle 95A.
So what category does running 3 wires in conduit fall under? This will make
a big difference on the wire I choose. I was going by the '3 wires in a
cable' table, which is why I chose the 2 awg THHN.
Something similar to a Square D D223N should work, I'd think. It would
have fuses on the inside, with the typical knife type switch that is
operated by a handle on the right side of the box, which is, for all
practical purposes, fully enclosed.
The fuse panel is on the outside of my garage wall, and the
If your panel will be attached with no elbows involved, your choice of 1"
conduit is adequate, at least by code. I'd strongly suggest you go to
1-1/4" conduit (or larger) if you have a couple elbows to pull through.
The larger radius and greater clearance will make pulling the wire
considerably easier. I followed my own advice in that regard. I had
to pull through three elbows.
This is not a shop, but just my 19x19 2 car
Man, does that sound familiar! My cars sat outside for years. All in
good time, Terry.
While I haven't gone to my literature, what you stated is exactly what I
recall. In my mind, the likelihood of people like us running a machine
anywhere near capacity for any length of time is almost non-existent. So
much so that I chose #3 wire to hook mine up. It meets the criterion set
forth by Lincoln, and the slightly smaller wire made the pull a little
easier. Not much financial gain, at least not in my case. If, by chance,
you can get #2 THHN for the same price as you'd pay for #3 or #4, I'd sure
as hell do it, unless I had some killer bends to pull through. You'll never
be sorry for having wire that's too large, only if it's too small.
I'm thinking you'd want to go with the #2 in the above example. The whole
idea, as I understand it, is that wires that are bundled, whether in a
conduit or a cable, have less cooling, so you'd look at the worst case
scenario to make your decision. I have no doubt that you would get by
just fine with the #4 because you're highly unlikely to ever run the machine
long enough for significant heating, but it wouldn't meet code. Again,
I'm no electrician, nor do I fully understand code. Still, I've wired two
shops on my own, both with three phase delta service, and have gotten along
quite well. Like you, I try to do things right, I don't cut corners.
Better hold off on the thanks until you find out if I've really helped you!
Keep in mind that I'm not an electrician, nor have I
actually seen the situation first hand, but that sounds
very conservative. If the run is short and the installation
is easy the added price of materials is probably worth the
peace of mind.
Don't underestimate the difficulty of pulling #2 wire
around multiple bends.