Wiring Questions

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Hello all.I own a MillerMatic 250, and I am about to purchase a Syncrowave 180 SD, and I would like to run a new 220 line to my garage that I could use for either machine. I have a few questions for anyone that can help.I would like to have just one outlet that I could use for either machine. I wont ever have a need to run both at one time, so as long as I have a breaker/wire size configuration that will safely work for both machines I am set. My MM250 manual calls for 10 AWG and a 70 amp breaker for 220. I dont know about the Syncrowave 180 yet.The distance from my panel to the garage is about 60ft.1) What gage wire should I use to run from the panel to the outlet?I was thinking 8/3 (one size up from recommended) but someone else insisted I need 6/3.2) The wire will be run through my attic. Does it need to be run inside of conduit or can I run the bare wire in the attic.3) What is the voltage for the electricity in my house? Is it 220 or 230?4) What would be the best/safest amp breaker to use in the panel for these 2 machines?I have an unused 60 amp breaker in the panel now. Would that OK?I will make sure to have someone more qualified than myself to do the actual hookup, but I am alread running a bunch of wires for lights and regular outlets, so it made sense to run the welder line at the same time.Thanks in advance for the help. Any feedback is greatly appreciated.Frank
Reply:Hi Frank;I will chime in here with the qualification that I'm not an electrician but do have experience there.    The first thing I see is that it is absolutely stupid to put a 70 amp breaker on a feedr that is only 10 gage wire.    This is a huge fire hazzard.    The fundamental mistake here is sizing the breaker for the machines need.    Unfortunately that is not why the breaker is there, breakers are designed to protect the wiring.    If a machine needs a 70 amp breaker then the wiring on the circuit should be rated for 70 amps.    A good electrician can clarify this for you.    In any event there are specific guide lines in the NEC (national electric code) that covers welders.    The problem is that once put a plug in place you really don't have a feeder to a welder rahter you have a branch circuit that needs to be hooked up correctly.    In any event, no matter what exceptions may be found I would not use wire any smaller than can be protected by the breaker.    I don't have my code book in fornt of me so I won't even try to geuss as to wire size.   For long runs you will need to take into account voltage drops also.Personally I would run the wire in conduit.    That is because I often DIY it and it is easier to install some EMT and then pull the wires thru.    You might however find that veeder cables can be used for this application.As to the voltage in you house, only your voltmeter knows for sure.    Around here I could swear that the utility drops the line voltage every spring.    Then you have the reality that voltage will vary a bit though out the day.As to Breakers read the first part of this message.   Breakers are there to protect the wiring and thus the structure the wire runs in.    That means that large breakers should not be feeding wire that can not handle the potential available current.    As to existing unused breakers the 250 is likely to run as it is rated 42 amps at 230 volts.   My current catalog doesn't cover the 180SD but the new 200 Syncrowave is rated at 54 amps.    If you max out this machine you may end up with trips you don't want.It might be to late but it might have made more sense to run a feeder to a 125 amp sub panel in the garage.    You could then wire everything into that.    The feasability of doing so depends on a few things,    In any event one positive aspect of such a run is that you get a lower voltage drop due to the heavy wire feeding the subpanel.    I don't know what the reccomended breaker size is for the Syncrowave, but I do have a concern that it might be less than ideal to try to run both welders off the same circuit.    This would especially be the case if the reccomended breaker size is 90 amp or greater for the Syncrowave.     So I would have to say that a 60 amp circuit might work, depending on how much of a load you put on the machine.In any event if I was doing this for myself I'd go with at least a 125 amp subpanel for the garage.   Then properly size outlets for both machines.    By the way you may find that the two machines need different outlets anyways.   The first goal with all wiring systems should be to assure safety.    You can't do that by running long runs of undersized wire.ThanksDave
Reply:FYI, I run my Synchrowave 180SD off a 60 amp breaker through a 50 ampere plug no trouble.  Shoot, I can hardly get the inner fan to turn on - I gotta be doing lots of 150 amp beads on aluminum before she kicks in.  Never a breaker problem, nor does the plug ever get hot.  You be fine with 60 amperes.
Reply:For 60ft you MUST use 6/3!!  I wouldnt trust 8/3 for that long of a distance.
Reply:Originally Posted by RubenZFor 60ft you MUST use 6/3!!  I wouldnt trust 8/3 for that long of a distance.
Reply:When in doubt, go to the source.  Miller, that is.If you go to www.millerwelds.com and "support" and "owners manuals" or the like, you can download the complete 52 page manual for the Synchrowave 180 DL.  Section 3-12, "Electrical Service Guide," in the manual lists, "Input Amps at Rated Output" as 54 amps, recommends a 60 amp Time-Delay breaker or an 80 amp standard speed "Normal Operating" or general purpose breaker.  I would guess that the higher rating on the fast breaker is to avoid nuisance tripping on momentary electrode shorts.They also advise minimum conductor size of 8AWG for power and grounding conductors and a maximum length of 147 feet.  THIS IS FOR THE CONDUCTOR BETWEEN THE PANELBOARD AND THE EQUIPMENT per NEC Table 310.16.  The note says, "If a flexible cord or cable is used, minimum conductor size may increase."I agree with wizard that running the conductors in conduit is a good idea, even if your code will allow other forms of cable.  It's not that hard to run in most situations and the peace of mind it gives you may be worth the hassle and cost.  However, wire of a given insulation temperature rating generally has a lower ampacity in conduit than in free air due to the inability to get rid of the heat as easily.I am also not an electrician and I advise you to get the recommendation of a qualified electrician in selecting the conductor/conduit combination.  I have had good luck finding electricians who would advise and provide guidance and do a checkout before you bring in the inspector.  For a small fee, of course.I also second wizard's recommendation that you install a 125 amp subpanel in the garage and feed the garage and the welder off the subpanel.  That's what I did in my garage.  It's handy having the power cutoff right there.Good luck.awright
Reply:Originally Posted by zero1ninerI have been advised recently that I need to use 6/2. That 6/3 is a waste since I will only use 3 of the wires. Is this correct?
Reply:AC is being feed  to the welder from the homes panel box.   (Atleas tin the majority of the cases, solar powered homes could be all DC, but that is another issue altogether).  Generally a call out of 6/2 would imply two power conductors and a ground when in reference to 220 volt residential wiring.   6/3 would be a system with 2 power cunductors, a neutral and a ground.    By the way the first number indicates the wire size, so in this example 6 is 6 awg wire.As to what the welder requires that will require reading the manual.   Not many of the welders I'm familiar with make use of the neutral wire so it could be a waste.    Some thought has to go into this though or you find yourself redoing work you thought was finished years ago.    It really does help to plan electrical systems.Dave Originally Posted by RubenZNo, 2wire only has 1 positive, 1 negative and a neutral.  3wire has 2 positives, 1 negative and a neutral which is what my welder called for.  Not sure what yours calls for.
Reply:Originally Posted by awrightWhen in doubt, go to the source.  Miller, that is.
Reply:What is the benefit of having the wire inside of conduit vs just running 6 NM in the attic space? In my situation, there is no point in the run where it would be exposed. It is inside of an enclosed studded wall to the panel, then in the attic, then inside of an enclosed studded wall to the receptacle. Is conduit really necessary?
Reply:Of course, the answer to your question, "Is conduit really necessary?" is in your local code.  I strongly suspect that it is not required by the code, but that's a question for your local inspector.  The advantage of conduit, however, is that pulling any wiring to the garage that you find that you want in the future is a piece of cake.  For this reason, if you do choose to use conduit, when you pull your wires pull and leave in place a new pull cord for the next time.Along with the earth ground provided by the conduit or grounding wire in the NM cable, you will want a ground rod at the location of the welder for maximum control of interference.awright
Reply:There are a number of ocassions where I prefer the use of conduit over NM cabling.   Wether they are advantageous is up to you and how the code is applied in your area.#1 Is that it can make installations easier especially in the case of heavier cables.   Especailly if the alternative is to pull the cable through bores in joists.#2 Is that in places the code would require the installation of support for the NM cable anyways.   Buying a bunch of wood to staple cable may not be economical.#3 Generally a fault is contained within the conduit if something should go wrong.#4 Long runs where an NM cable would take a lot of abuse.#5 Exposed work in a garage or cellar.   For example I wired strings of lights in my cellar with EMT and BX whips to the fixtures.    This is in my opinion safer, it is where my shop is at the moment and I'm always getting things hung up on existing wiring. {Don't ask what happened to the phone lines  }   The other plus is no more bores in the joists so we don't impact strength nor work hard at installation. Originally Posted by zero1ninerWhat is the benefit of having the wire inside of conduit vs just running 6 NM in the attic space? In my situation, there is no point in the run where it would be exposed. It is inside of an enclosed studded wall to the panel, then in the attic, then inside of an enclosed studded wall to the receptacle. Is conduit really necessary?
Reply:OK. I have really been all over the fence about this, and I realize I have labored over this entirely too much...but, tonight I bought 100' of Liquidtight Flexible Nonmetallic Conduit (Carlon Carflex brand). My thinking behind this decision was that this way I can run three 6 awg wires through there now, and if I ever need a 4th neutral wire later for whatever reason, I can pull that through at a later time without having to tear out the 6-2 NM and replace it with 6/3 or whatever. The cost difference was about twice the price. The 6-2 NM cost me about $100 for the run, and the conduit and the 3 wires of 6 awg will cost me about $200.Two questions:1) Does the NEC allow for me to run the flexible conduit for that long of a run (approx 60 ft)? Seems like I just read something about being limited by how long I can run this??2) As I mentioned before, I am running this from the panel inside of an enclosed studded wall, through my attic, and the back down an enclosed studded wall. The question was is it OK to just bend this flexible conduit at the 90 degree bend points when I transition from coming up the wall to the attic space, and then again from the attic back down the wall?Anything else I should be thinking about by using this flexible conduit method instead of the simple 6-2 NM option?
Reply:1)No limit on conduit runs. In your case you are merely using the conduit in lieu of a jacketed cable.2)No kinks. A good rule of thumb is the 'ten times the diameter' rule for the wire. You will, however, see licensed electricians do some horrible things to large wires in EL's. The main focus of the 'ten times' rule has to do with extreme high voltage/lightening hits. So use the 'no kinks' rule.Anything else I should be thinking about by using this flexible conduit method instead of the simple 6-2 NM option?
Reply:Originally Posted by SandyGet it done.
Reply:Originally Posted by Sandy2)No kinks. A good rule of thumb is the 'ten times the diameter' rule for the wire. You will, however, see licensed electricians do some horrible things to large wires in EL's. The main focus of the 'ten times' rule has to do with extreme high voltage/lightening hits. So use the 'no kinks' rule.
Reply:Originally Posted by zero1ninerI understand no actual 'kinks', but regardless of whether I bend the conduit 90 degrees or use an elbow, I will still be bending the wires about the same amount wouldn't I? Also, what I bought was 3/4" (this was the largest they had in stock). Am I pushing my luck trying to get four 6 awg wires in a 3/4" conduit?
Reply:In reading back through this thread I'd like to ask just what materials you do have on hand to do this job. I see reference to some 6/2 NM as well as three number sixes. Keep in mind that for a ground wire the ground doesn't necessarily have to be the same size of conductor as the hots. As far as pulling in a fourth wire later or utilizing an already placed spare fourth wire later that ain't gonna happen as easy as you think. A 'dedicated circuit' is a "dedicated circuit".
Reply:Let's eliminate the 'worry factor', otherwise these posts can go on forever discussing what the ideal set-up can be. Wire sizing for continuous duty. The NEC (bulk of the NEC) dictates wire sizing for continuous duty. This is the result of many great minds and years of practical experience. If the NEC says we can down size for dedicated welding circuits let's believe them. They won't let you create a risk. Circuits designed for continuous duty are triple idiot proofed. Continuous duty by todays standards means ( let's use a number 12 circuit) that I can plug in a 19.5 amp something or other and go off on vacation and my home will still be there when I get back. This thing will run 24/7 all this time. At worst the wire might be warm but far less than the 190 degree melting point by far. This just isn't gonna happen with a welder. You have to be on the end of it to make it go unlike a compressor or such. There are devices in place to cover the bulk of other problems that might occur. Nothing is going to catch every possible scenario. Wizard and awright have steared you in the direction of safety and that is great. We have to remember the NEC lists minimum requirements so upsizing is a good thing here. Now that you have some #6 you are good to go by a long shot. A welder is not and will not be continuous duty. Not yours anyway.  If you have some 6-2 romex put it in a don't look back. Put it in conduit in the wall sections if you feel like you have to. Do not put that in conduit for the entire run. As awright mentioned there is a heat build up issue and the insulated-jacketed wires get derated when put into conduits other than short conduit runs coincidental to mechanical protection, ie exposed portions. In fact exposed in an attic is a good thing, it allows for heat dissipation. It wouldn't hurt to put in a staple in a place or two for earthquake protection since you won't have any in the walls.If you have 3 individual #6's in hand then those are great too. Those must be put into a conduit since they are not double insulated (insulated and jacketed). If you can get all three of those in a 3/4 inch conduit get'r done, and again, don't look back. The #6 ground is much larger than required but it's what you've got, no big deal.  If you have a double 60 amp breaker start with that. If it trips then it's doing what it is supposed to do. Upgrade if it gets to be a problem. Upgrade to within reason that is. If in doubt check out the 630 (??? I think) section of the NEC for derating and sizing for dedicated welding circuits. You will likely start off with a 6-50 receptacle anyway. The 50 stands for 50 amps continuous duty. If you ever get to worrying over wire size and breakers, feel that plug and receptacle for anything more than casual warmth. The reason I brought up the potential of converting those number sixes to a sub-panel later is the fact that the instant you put in that sub-panel is those #6's will fall back under the category of continuous duty, 50 amp breaker and the hole bit. If you came off that with a new circuit for your welder(s) it's easy to see what the limiting factor would be. Your newly created sub-panel wouldn't have a large enough breaker to (in concept) to run your welder. In actuallity it might but at face value, no. See how tuff it is to plan on the future? . Do what you need to do today, do it good, and deal with the future when it gets here. If you want a panel for the shop/garage do it right and do it now, big enough for all equipment and tooling.  Anyone???  Check my logic here guys.
Reply:I'll bet by now zero1niner wishes he hadn't opened the floodgates by asking us for our advice.  But here comes more.I have to challenge Sandy's comment about using Romex inside conduit.  I don't think that is allowed, but that's based on distant recall.  It has to do with temperature ratings of the insulation on wires used in Romex and the effect of restricted ventilation (cooling) of wires inside conduit.  This is just an alert.  I don't actually know the rules about that.Let me just take a minute to lean down to strip some sheathing off the Romex sticking out of the wall next to my computer......   Yes, just as I remembered.  There is no temperature rating printed on the wire insulation inside Romex.  In fact there is nothing at all printed on the insulation.  I guess ratings are handled by the printing on the Romex sheath.  But what that means is that you don't really know what the temperature rating of the wire is and, therefore, you would presumably have to assume that it is the lowest temperature rating of common wires, such as TW or THW.  Table 3A of the NEC (National Electrical Code) shows that only two conductors of #6 TW or THW can be used in 3/4" conduit.  And I'm sure things get worse, thermally, if you put the whole Romex cable into conduit.  The bottom line is that you really should have a knowledgeable person (not me!) advise you on such matters.  There are many rules and many exceptions to the rules, and they are not there just to harass us.  My guess is that you would be busted big time if your electrical inspector or insurance adjuster saw that you had Romex inside conduit.Another thing I don't know much about are permissible 'WIRE FILL" for various sizes of conduit and various applications.  I do know that you have to be careful about it, though.  I also know that there are special considerations for welders due to the duty cycle issues mentioned by Sandy and others.  BUT, looking at Table 1 of the NEC, for 3 or more conductors in conduit and tubing, permissible wire fill is 40%.  However, a footnote comments on how to treat multiconductor cables in conduit, so there you go!  That's why electricians sit in classrooms and subscribe to on-line electrical code services.awright
Reply:Geeesh. Just to clarify a few points. I never really intended on running the NM inside of the conduit. I may have written something in a funky way that would lead one to think that, but it was not my intention. What I actually was thinking was that I would run THHN inside of the conduit. Now that you all have mentioned the 40% fill problem, and the PIA it will be to cram 4 wires into the conduit, I am thinking that I will go back to my original idea of the 6 NM and forget about the conduit altogether. Sandy, thanks for putting this all into perspective. My head was starting to spin a bit. I was really looking for the BEST possible solution, and I now realize that I had an acceptable solution a few days ago (this would be the 6 NM without conduit solution). As far as thinking down the road, crap...Im lucky if I know whats going on tomorrow let alone 'down the road'. I will plan for tomorrow another day. So long as I will not be doing something stupid that will burn my place to the ground, I am happy.  I will run the romex tomorrow and be done with it once and for all. Thanks everyone for the help. I truly couldn't have done this without your help.
Reply:Hey awright,On the issue of romex in conduit, it is true that you cannot pull/put romex through conduit. There is also the rule that you cannot have any exposed wiring below a certain height. This presents a problem in open walls like you might find in shops and utility buildings. To solve that they used to allow you to put just that portion from above the joists down to the receptacle in conduit. More of a waver rather than having to put in a splice box or make the entire run in conduit. If you continue from box to box below ceiling height you would have to change to conduit and individual wires. I also haven't reviewed the codes or local practices for more than a few years either.
Reply:wow that takes me back--the electrical code -- WOW brain  tummor --like in 1976  wow