i have a millermatic 251 and some other shop equipment that i want to get wired but not sure what wire to use...the shop i worked at approx. 3 months ago had their electrician run some red, green, and black wire rated at 600 volts but no specific amp rating on it, throughout the shop...we used the same welder and plasma cutters and such...i want to do my new shop the same if it's correct and will handle the amp and voltage load safely....i think 6-3 would be too hard to wire my building with and still be cost effective...the wire i am referring to is about 1/8" thick with multiple copper stranding and is in a slick, smooth jacketing...says oil and gas resistant, rated at 600 volts, etc...never had a problem with it at the shop i worked at and i worked with it all day long...help me out here so i can run my wiring and get an idea of price and materials needed...also wanted to run it inside plastic/pvc electrical conduit instead of in the wall so i could fix/add to it if i needed too...breaker box is 300 amp with (3) 30 amps, (3) 20 amps, and (2) 50 amp breakers if that helps.
Reply:According to the Miller datasheet on the 251 it draws about 42A at 230V for the rated output. So basically you need a 50A circuit. According to the NEC 6AWG wire will handle 55A at 60 deg C which is the standard rating. You didn't say wheater or not you were direct connecting the welder or using a plug and socket. Either way you are supposed to have a service disconnect within sight of any 220V piece of machinery. Apparently a plug is not a disconnect. So for each circuit that you want to run the welder from you need a 50A breaker and 6AWG wire. Also you didn't specify the run length. Price estimate for a single 50A circuit. 1. Breaker $152. 50ft of 6-3 wire. (I would buy 150ft of black THHN wire and use tape to designate RED, BLACK, and GROUND) $753. Conduit & Couplers (I would use 3/4" EMT conduit instead of PVC) $354. Disconnect 60A $155. Misc $25Total $165These prices are based on current home center prices. Have fun.
Reply:i planned on running emergency mushroom push/pull switches rated for this applocation...i have one installed in our paint booth and it passed fire marshall code here so i think it would work for me here as well...the pvc type conduit i was referring to is the grey type that is made specfically for electrical work...as far as the breakers and such, i already have that figured out...what i wanted to know was if the wire i asked about is good for the application...the welders and such will not be permanently mounted as i will have to move them around for one reason or another at some point...the wire feels like it could hold the amperage and volts and as i stated before, we have it already in our shop now but just wanted to know if this is a good idea since it isn't the jacketed 6-3 that comes as one big wire, it's three seperate small wires that can be run individually in the conduit with a snake.
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ops...forgot the length...the shop is 30x50 and will have multiple outlets around the shop for each type of equipment
Reply:Yea 6-3 is the correct wire for a 50A circuit. One big wire would be a little more difficult to snake through the conduit than three smaller wires.
Reply:You wouldn't want to run 6-3 so or soow cord inside a pipe anyways it is meant for outdoor application like an extension cord or for mobile aplications such as movie sets or carnivals. 1/8" is around 10 AWG wire that will not be big enough. That is only rated for 30 amps and a 50' run with a 42 amp draw would cause a voltage loss of 5 volts. Your amperage will go up as well and that will cause the wire to heat up. You will cause the conections in the welder to heat up as well and in the end you could do damage to the welder.Go with the 6 AWG like suggested above it is rated for 50 amps and is what should be used to keep with the NEC code.
Reply:thanks guys....went out lat weekend and got all the info for the stuff i need....should be a good set-up when i get the shop built...is it hard to have 3 phase put in or do i need some special box or permits?
Reply:Three phase is a completely different animal. Are you talking home shop or business shop? When I looked into it for my home shop, the thing that stopped me were "demand charges" from the power company. Basically, they look at your peak demand and then you get charged for them being able to supply you with that. Not a problem for a company with consistent daily power usage, but for a home shop you would have to pay a demand charge based on the one day of greatest use out of the month. Got pretty pricey. I'm also not sure that they would even set it up for a residential customer, although I know a couple farmers that have it. But that is another ballgame. And yes, it does require a different meter, panel box, etc.
Reply:When we had the line droped into our shop when it was built about 6 years ago it costs I want to say around $8,000 to have 3 phase put in. That was just the lines from the poll to the shop. This was in a new building so it was a new isntall that might be why it was so expensive.Then you need a 3 phase distribution pannel that wasn't cheap either. Then depending on what type of equipment you run you might need a transformer to step the voltage down from 460 to 220 which we also had to buy.Any way you look at this it isn't cheap if you are only using it for 1 or 2 peices of equipment. The stuff we work on and repair is all 3 phase so we don't have a choice.
Reply:Re: three phase You can "make" your own three phase with a converter. Many choices can be found on eBay, on do a net search. There is at least one person on eBay that has put together a little book on it, how to make your own converter, wiring your shop, etc. Also, try "Lindsey's" publications, I think they had a "how to" in there list. It is really a very simple matter for anyone with basic mechanical/electrical background.Just my opinion, not from a book, just from the road.Howes Welding Inc.www.howesweldinginc.com
Reply:Most of the how-to books on phase conversion deal phase converters for motors. Three phase welding equipment is a different ballgame and the equipment to convert phases is much more expensive than that for simple motors.
Reply:I guess I really lucked out with my house. It has 3 phase. If you still need wire let me know, I have a 1000ft roll of 6-6-6 service entrance wire and a couple hundred feet of 4-4-6 SE wire.
Reply:kinda put a damper on my plans for gettin 3 phase put in...wait....if miller sells most of their welding equipment that is for serious fabrication as three phase, then why wouldn't it be cost effective to have it run in a residential/commercial shop?...seems strange...i am gonna call my power company today ad find out what it takes....i will get back and let you know!
Reply:The key to what you said is Residential / Commercial. Most buildings with 3 phase are zoned industrial. I don't know of anyone with 3 phase in a residential except maybe farmers. I know there are probably some who do but I don't know of anyone. Almost all of the buildings zoned commercial I looked at didn't have 3 phase and the ones that did wanted top dollar for rent. I guess a lot of it would depend on what part of the country you are in and the local codes. Here they are strict and enforce the zoning laws hard. If I were to work out of my garage (not that it's big enough) I would get fined. I got a ticket for parking my dually in my drive over night, so if they saw sparks flying in the garage they would have a field day.
Reply:jeez...just got off the phone with my power company earlier and they said it's cool, all i got to do is hae them come and look to see what is involved in running the lines from the street to the shop...
Reply:When I looked into it, they would supply me with three phase - no problem.The problem was "demand charges" for the service. Here is a definition that I found:Electric demand refers to the maximum amount of electrical energy that is being consumed at a given time. It is measured in both kilowatts and kilovolt amperes, depending on the rate tariff. The difference between the two terms is power factor.Another related term is kiloWatt hours, which is a measurement of total electricity used for a period of time. A 1000 watt electrical load used for one hour consumes one kiloWatt hour (kWh).Electrical Utilities typically charge commercial and industrial customers for both consumption (kWh) and Demand (kWd or kVa).As everyone knows, electric rates vary by state and utility company. Utilities have different tariffs for different types of customers (users). Larger users tend to get more favorable rates than small users. Some utilities offer different rate periods based on time of day or calendar periods. Others charge flat rates regardless of the time or the days. In this explanation we will use sample tariffs from two local electric utilities.The electric utility has to be able to maintain enough generating capacity to service everyone's needs at any given time. They do this by generating the electricity themselves or by purchasing the electricity from other producers. In most cases, it is more expensive to buy the electricity from other utilities.Large users that use varying amounts of electricity at sporadic, different periods of the day or months raise havoc with the electric utilities operation. These users are assessed demand charges (penalties) as part of their normal monthly billing. The demand charges many times exceed 50% of their total electric bill. This makes "Demand Side Control" very attractive to reduce a companies operating expenses.The last paragraph was what killed getting three phase for my shop. If I had the same demand day in and day out, it would not be so bad. But one weekend of heavy welding would set my rate for months and I'd have to pay the penalties for that peak usage.Make sure that you discuss the fees and charges involved before you commit to this. They were more than willing to set me up with three phase because they were more than willing to take my money...
Reply:good point....i did ask them about it and the guy said he didn't deal with that type of work or area in the company so he got my number and said someone would call me back and talk to me about it...we'll see...if not, i will get the new millermatic 350 and use is single phase.
Reply:Yeah, I nearly made that mistake. Talked to the "engineers" about it and was all ready to get 3-phase service. Somebody I knew hinted that I had better talk to the utility's business office and mention "demand charges" to them before I went ahead with things.After a somewhat lengthy and roundabout discussion I realized that my electric bill would be about double to triple because of the demand charge and not just that I would be using more electricity.
Reply:My trun, the only thing that hasn't been mentioned is the aluminum vs copper wire .My preference would be copper is you can, the aluminum creates problems, corrosion, loosening of connections over time.Luck,NnF
