Wireing in new Miller 250DX

[Jammer]

I just bought a new miller 250DX T.I.G, Stick Welder, and wanted to know If anybody here knows how to wire it. I have a 100amp service in the garage with 240v coming in. I need to know how many AMP breaker I have to use to run this machine. Any help would be appreciated.

[awright]

Lucky guy!

Wish I could learn how to lift parts of the Miller data sheets and retain formatting. But I haven't, so I have to describe what I see in the spec sheet.

Page 3 of the Miller 250DX Product Data Sheet

(http://www.millerwelds.com/pdf/spec_sheets/AD4-2.pdf)

shows three different listings for three different configurations of the 250DX; 60 Hz, 50 Hz, and 50/60 Hz. You didn't say which yours was, so I'll assume the worst case (60 Hz. only) as an example. Since there is a significant difference in maximum input current between the three models, you will want to be sure to use the correct table.

There is also a difference in current demand depending upon whether you have power factor correction or not. I will assume that you do not. (You would benefit from it. See the extensive discussion of PFC in other threads here in "electrical.")

Under the "230V" column, the top table (60 Hz only unit), and without PFC, the input current is 77 amps at 200 amp, 28VAC out, and 96 amps at 230 amps, 30 VAC out. To properly supply this machine for its maximum performance, you should have a 100 amp dual, ganged breaker, which is essentially all your house power. Not a good situation. It is not a good idea (and probably a code violation) to supply a piece of equipment with less than its rated current and rely on the protective circuit breaker to limit the current you can draw.

Note that you can reduce your maximum input current demand to 52amps and 71 amps, respectively, by using the power factor correction kit on the 60 Hz only model. This is a lot more reasonable for a house with 100 amp service. You would then be able to use an 80 amp dual, ganged breaker and, possibly smaller wire size. 20 amps reserve is probably enough for routine household demands during the limited times you might be using full power at your welder.

As an amateur, I hesitate to recommend a specific wire size for liability reasons, but you can find the "ampacity," or current-carrying capacity of various wire types and sizes inside conduit in books on wiring or in the electrical code book. Be sure that you are using proper wire type and temperature rating for the actual type of installation you have. A qualified electrician can provide you with very valuable guidance.

You will definitely want to install your wiring to the welder inside metal conduit for shielding of electrical noise radiated by the wiring to a welder, and you should install an earth ground rod at your welder power outlet, also for safety and noise control.

I advocate being liberal in sizing conduit and wire size so you will be ready when your ambition expands and you rewire your house for 200 amp service (as I did).

Hope this helps. Gotta go.

awright

[awright]

Oops! I mis-remembered your comment about service level to your garage, thinking you had said service to your house. Using most of the wiring capacity to your garage for the welder is probably OK because you will not be having other high current demands while welding and you would very rarely be using full rated input current. What is the level of service to your house?

My other comments about having your service to the garage and the machine inside metal conduit still apply for electrical noise control purposes.

[Jammer]

Hey awright:
First of all, thank's for the reply. I can see from the long reply you really did some hard research on this and I really appreciate it. I don't know where you come off calling yourself a novice, you sound from the reply more like a damn "Electrical Engineer". I have a friend who's son has been an electrican for about a year now and he was unsure how to hook this machine up, so I figured I'd post it on the "Welding Web". Anyway, I'm not sure how many Hz. this machine runs on but I will find out and I'm sure between the Information you have given me and my friends son we'll be able to hook this machine up with minimal problems. By the way, I have a 200Amp. service in the house.
Listen, thank's again for the reply, you've been a great help.

[awright]

Jammer, thanks for your kind words. However, this is a good lesson on taking amateur advice on important matters as the last word.

Having responded to a couple of such requests, I thought, "Surely the manufacturers must offer advice on installation." So I used the, "Miller Contact Us," form at www.millerwelds.com to inquire about just what the several different entries in the eletrical input characteristics meant and how they related to the input power requirements. The response came in a couple of days and is reproduced below:

"Dear awright,

These ratings are for the same machine at different voltages (28 and 30 VAc), different duty cycles ( 60% and 40% )
Do not use these values to determine how to wire your shop.
The wiring and breaker size/ information can be found in our owners manuals.
To get this information go to our web site: millerwelds.com
Select "product" in pull down menu
Scroll alphabetically to locate Syncrowave 250 DX
Select owners manual for this machine
Find "electrical connection"
There will be a chart describing breaker size, and wire sizes.
If you have any further questions please let me know .

In case you are having trouble finding this information here are the recommneded breaker and wire sizes for a Syncrowave 250DX

On 230 volt single phase primary power use a 125 amp time delay breaker.
If you will not require full output of the machine you can use a 100 amp time delay breaker.
Wire size for 230 volt primary should be 6 gauge.
Thank you for contacting Miller


Jack Fulcer
Business Development Manager
Miller Electric Mfg Company- Tig Business
N822 Communication Drive
Appleton, WI 54914
Business: 920-954-3616
FAX : 920-954-3633
E-mail : Jfulce@millerwelds.com

>>> "Miller Contact Us" <aiaw@earthlink.net> 3/1/2006 10:52:55 AM >>>
Technical Assistance inquiry from the web

Subject: 250DX data sheet
Comments: I note that your 250 DX product data sheet shows two entries in
the "Rated Output" column, one for 200 A, 28 VAC, 60% Duty Cycle and
another for 250 A, 30 VAC, 40% Duty Cycle. My question is, are these two
entries for different models or versions of the machine or are the two
entries for two different modes of use by the operator? In other words,
if I am sizing my power to the machine, do I decide how I will typically
use it and provide maximum current accordingly, or do I select a specific
machine and provide the power for that machine?

Thanks.
awright"

So my advice to all inquiries about how to wire for a given machine is now, "Get the owner's manual and follow the wiring directions therein."

I do note that Mr. Fulcer doesn't make a distinction between 50Hz, 60Hz, and 50/60Hz models or between machines with or without Power Factor Correction. However, page 30 of the owner's manual DOES make a distinction. I still don't know how to place a properly formatted page of a PDF file here, but it says that the recommendation is for a time-delay breaker of 125 amps with #6 wire for a machine without PFC and a 90 amp time-delay breaker with #8 wire for a machine with PFC. That's for 77 input amps without PFC and 61 input amps with PFC at rated output.

There you have it from the horses mouth.

The owner's manuals also show proper wiring and grounding techniques.

Have fun with your new machine.

awright

[Jammer]

Hey awright:
All I can say is Thank's again. I turned the information you sent me from Mr. Fulcer over to my friends son and he said it had everything he needed to hook the machine up properly. I don't know how to thank you enough so I've decided to dedicate my first welding job in honor of you by welding your "Handle" into it. I know it ain't much but at least it's something.

Jammer:

[awright]

'preciate the kind words, Jammer. Nice to know it was helpful to you.

awright