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    #16
    Originally posted by infinity View Post
    Can you slide a smaller diameter piece of EMT or RMC into the existing raceway to protect the conductors while cutting? You should be able to cut around the EMT.

    Great idea

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      #17
      What about a Klien Electricans Tubing Scoring Tool, scores and than emt is snapped
      https://www.homedepot.com/p/Klein-To...8906/100662410
      Moderator-Washington State
      Ancora Imparo

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        #18
        Originally posted by Cow View Post
        How will the box be supported?
        by using a condulet instead?
        ~New signature under construction.~
        ~~~~Please excuse the mess.~~~~

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          #19
          In terms of cutting EMT I am not a professional; but in my DIY experience the 'score and snap' approach works pretty well. Sometimes it leaves a burr and sometimes it does not.

          My biggest concern here is deburring the cut with conductors in place. Is there a bushing made for emt similar to the 'red heads' used for AC cable?

          Regarding 'cord and plug' connection for the control lines; there are loads of connRegarding the 0-10V control lines being 'plugged in' there are loads of low voltage connectors available. It looks like 'XLR' connectors are pretty common for DMR lighting. My understanding is that the control lines should be separated from the power lines, so I don't think the low voltage connector can be in the same JB as the power connector.

          -Jon

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            #20
            Originally posted by electrofelon View Post
            Try one of those deburring tools if you havent. They are slick.
            I have both, used a tubing cutter, and one of those deburring tools. Usually the lip that is left is too much for the deburring tools to remove, honestly, at least. For Tom Baker, IMO the Klein scoring tools is really just a pipe cutter marketed under a different name. Using a sharp blade on a tubing cutter and using more revolutions in lieu of more pressure will reduce the lip. then I have still only found a rat tail file effective at removing the burr. I much more ideal way to do this work is to tie a string to the wires, pull them back and use a blade to cut the conduit. Still trying to prevent cutting the string, but if you do, it will just take some work to get it back out. One other thing I have done. Score it with a pipe cutter and then carefully cut around with a hack saw. Also, if you are putting a junction box on the end, the pipe can be cut about ten inches from the end first, since all you will need is 8 inches of wire when you are done.

            From a specifying angle, and I am an estimator. I Would greatly appreciate you identifying the problems, but not the solution. Let me decide how to do it. Methods may change depending on the situation.


            I know what I don't know, and I know where to go to find it!

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              #21
              Originally posted by Strathead View Post
              I have both, used a tubing cutter, and one of those deburring tools. Usually the lip that is left is too much for the deburring tools to remove, honestly, at least.
              Yeah I know what you mean. There can be a rather large ridge of deformation from the wheel. Although I don't really have a problem with that, as long as it's not sharp. Not rrally much different than the ridge at fittings , imo.
              Ethan Brush - East West Electric. NY, WA. MA

              "You can't generalize"

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                #22
                Push a large red head into the end of the conduit after you score and snap. Wrap it with electrical tape if you feel the red head is going to slip off.
                85deg. an Sunny today.

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                  #23
                  Originally posted by macmikeman View Post
                  Push a large red head into the end of the conduit after you score and snap. Wrap it with electrical tape if you feel the red head is going to slip off.
                  And you feel that is compliant with code? i don't.


                  I know what I don't know, and I know where to go to find it!

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                    #24
                    Originally posted by electrofelon View Post
                    Yeah I know what you mean. There can be a rather large ridge of deformation from the wheel. Although I don't really have a problem with that, as long as it's not sharp. Not rrally much different than the ridge at fittings , imo.
                    Not, and those deburring tools don't "round it off" like a fitting. If you stuck your finger in, pushed against the edge and ripped your finger out, you would not think the edge is harmless.


                    I know what I don't know, and I know where to go to find it!

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                      #25
                      Originally posted by Strathead View Post
                      And you feel that is compliant with code? i don't.
                      Well neither is cutting the conduit with the conductors inside it either. Raceways must be complete before pulling conductors. Nobody ever violates that though.
                      I live for today, I'm just a day behind.

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                        #26
                        Originally posted by kwired View Post
                        Well neither is cutting the conduit with the conductors inside it either. Raceways must be complete before pulling conductors. Nobody ever violates that though.
                        You have me there, as the evidence is in a recent thread. Then again, technically the code doesn't say the raceway can't be modified AFTER it is complete.


                        I know what I don't know, and I know where to go to find it!

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                          #27
                          Originally posted by malachi constant View Post
                          Ooh, I have another somewhat related question! A few fixtures being added that are RGB DMX color-changing type high-bay floods. These are brand new locations, so we will be adding conduit to these locations. These will require 0-10V control wiring to them.
                          Are they DMX (which is electrically RS-422 differential pair) or 0-10v? Completely different animals. DMX usually uses 5-pin XLR-type connectors (or occasionally 3-pin XLR), but in reality any low-voltage connector will do. Use a location-compliant low-voltage cable from fixture to the connector, then take that into the new conduit.

                          If it is real DMX, I hope someone is paying attention to things like splitters and terminations.

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                            #28
                            Originally posted by malachi constant View Post
                            Hi all,

                            I am designing a lighting retrofit where the Owner requests a one-for-one replacement of highbay lights. The lights are currently hard-wired, and the Owner wants the new lights to be connected via cord and plug. There are a few hundred fixtures and downtime (plus other costs) needs to be limited. The hardest part to factor is the conduits disappear up into a fabric insulation ceiling which presents two problems. One, the insulation may or may not be hiding junction boxes. And two, it is difficult (impossible) to visually trace conduits to see what goes to where. I'm concerned that we will need to cut the conduits a few feet short to allow the outlet box to be installed, but in cutting the conduit short we will sever the wire within it. It will be hard to pull back wire given the conditions.

                            I tentatively proposed a solution that sounds viable but I've never heard it done before: use something like a pipe-cutter (like used on copper plumbing pipes) to cut two feet off the EMT without damaging the wires within. Drop off the two feet and slide a box over the end. Is this something that is done? The maintenance folks thought it was a slam dunk idea but before I sent it out for public bid I figure I better make sure it is a viable option.

                            I'm guessing I'll hear other solutions from the community, so will add a little more information. Most of the fixtures already have a cord and plug, we're talking about maybe 15% of the fixtures. We'd like to keep them all in the same location at the same height - it's a nice existing grid that lines up with a number of other systems, limiting the ability to move things over or drop the heights. It's a high-profile event space, with some arena seating that will keep some spectators near eye level with the lighting, bolstering the need to keep it looking clean and neat. All that to say it would be really nice to cut the conduit a couple feet short without severing the wire.

                            Let me know your thoughts. Thanks!
                            While some of the recommendations are workable-- albeit difficult to achieve with varying results. Some may not give you peace of mind after all is said and done.

                            The “scoring approach” would certainly work by using a plumber's tube cutter. The problem with this is -- it will leave a razor-sharp burr that will likely cut though the insulation. Deburring it with any type of tool also has the potential of further damage to the insulation.

                            Scoring the conduit with pipe cutter won't be a “cake walk” either. You need ample clearance to turn the tool as you go around the circumference of the tubing. This will only work on EMT not with rigid conduit.

                            I've done this when I converted my sodium security lights on both sides of the house to LED Luminaire. It was mounted about 15 feet high—and the riser was one solid ten foot surface mount EMT. I had to mount the LED fixture lower than 15 feet.
                            Pulling the wires back was not an option because the conduit disappears through the wall to a junction in a soffit inside the house.

                            So, I used a high speed Dremel grinding tool with metal cutting disk about 1 ½ inch diameter. The 1/8 inch dia shank is where the cutting disk is screwed into. To prevent the cutting disk from cutting too deep (hence injuring the conductors) I slipped a piece of plastic ferrule on the Dremel shank, and exposing enough of the cutting blade to cut through the wall thickness of the pipe.

                            You don't have to cut all around the circumference of the pipe—only about three quarters of the pipe circumference is more than enough to snap it clean. The Dremel tool doesn't need a lot of clearance from the wall.

                            A minimal rough edge on the pipe can be smoothened (if you so desire) even with your wife's or girlfriend's nail file.

                            Just let her know before hand though—not spoil her holiday festive mood. LOL

                            Now, I can sleep better-- not having to worry about short-to-ground problem in high humidity and wet conditions this time of year. The inspector gave me a "high five" when I told him how I did it.

                            If the above doesn't give you enough peace of mind and confidence-- that the work is done safely-- you can get small piece of “fish paper” used in motor rewinding to insulate the stator magnet wire from the laminated core.

                            This fish paper is not the type that is used for wrapping salmon fillets at Walmart.
                            This is the one used in electrical repairs and manufacturing. . . and available on line.

                            BTW: I hope you are not like me. . .I have a mild OCD.
                            I'm not always satisfied with how things are done satisfactorily - -a hard-to-please codger.

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                              #29
                              Junction boxes above the fabric ceiling would be a violation anyway. I didn't realize that EMT could support light fixtures...
                              Electricians do it until it Hertz!

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                                #30
                                Originally posted by JFletcher View Post
                                Junction boxes above the fabric ceiling would be a violation anyway. I didn't realize that EMT could support light fixtures...


                                The Luminaire is mounted on the stucco wall. The EMT is not supporting the fixture. What makes you think so?

                                You are referring to op's post right?
                                Last edited by myspark; 12-05-18, 06:19 PM.

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