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Can (3) 6-20r 20 amp 208v Duplex Receptacles be on a 60 amp circuit?

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    #31
    I'm not so sure the NEC stops at the wall receptacle. I've been spending the last few months, and probably the next year, assessing anything that "plugs in" for NRTL compliance. For things that are not NRTL listed, we can hire a field evaluation body to bless it, or we have some employees that have been designated as allowed to bless the item. This involves some NEC basics (guarding, grounding), and verifying the bonding of exposed metal with a bonding meter. This is being pushed by OSHA and has actually been a Washington State rule for quite some time. It is just difficult to enforce, as the electrical inspector is the only one who typically looks at utilization equipment, and cord-and-plug things are usually not there when the inspector shows up.
    Mark
    Kent, WA

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      #32
      Originally posted by cottora View Post

      There will be a 30' shelf running down the middle of the container (100 per shelf, 8 shelves)
      100 in 30feet or 800 in 30 feet?

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        #33
        Originally posted by cottora View Post
        This is an off the shelve Power Distribution solution for our business. Here is the thing, this is essentially creating a tap. This 50AMP 6-50 gets split into eight c13 cords. But the C13 cables are not rated for 50AMP (they are 12AWG). That being said, the C13 will never draw more than 15 amps (unless shorted). Does NEC "stop" at the receptacle as I can't image this being allowed to be hardwired? Thanks

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        I found the ebay listing for these. It looks really shoddy -4S box with multiple cords going into NM cable clamps. Have a fire with one present and good luck getting the ins co to pay.....

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          #34
          Would one of these make any more sense? https://www.tripplite.com/5-5.8kw-si...ical~PDUMV30HV
          This one uses an L6-30 plug and costs around $240, or you can get them in L6-20 for about $75 less but will be installing more receptacles. I like these because of the ammeter on the front. Server type PDUs have these IEC type outlets, but getting short C13/C14 cords is easy. IT loads are difficult to predict unless you've metered one of these mining machine while its doing its business. Getting that load wrong many times has you putting in more power than needed which means more cooling than needed.
          Mark
          Kent, WA

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            #35
            Originally posted by suemarkp View Post
            Combined with fused PDU above, If NRTL labeling of 6-50 to L6-30 adapter is not counterfeit, NEC 240.21(B) may allow the tap to 6-50R on #6cu feeders per NEC Table 210(B)(3), 210.24, or perhaps >50A feeders per 210.18 Exception, 210.23(D).
            Roger Ramjet NoFixNoPay

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              #36
              Originally posted by Todd0x1 View Post

              100 in 30feet or 800 in 30 feet?
              800 Total on all shelves running the entire 30'. Google "miner container"

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                #37
                Originally posted by Todd0x1 View Post

                I found the ebay listing for these. It looks really shoddy -4S box with multiple cords going into NM cable clamps. Have a fire with one present and good luck getting the ins co to pay.....
                I believe that you are correct. That said, from a practical standpoint, there is nothing that can burn but the cord.

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                  #38
                  Originally posted by suemarkp View Post
                  Would one of these make any more sense? https://www.tripplite.com/5-5.8kw-si...ical~PDUMV30HV
                  This one uses an L6-30 plug and costs around $240, or you can get them in L6-20 for about $75 less but will be installing more receptacles. I like these because of the ammeter on the front. Server type PDUs have these IEC type outlets, but getting short C13/C14 cords is easy. IT loads are difficult to predict unless you've metered one of these mining machine while its doing its business. Getting that load wrong many times has you putting in more power than needed which means more cooling than needed.
                  Those would be ideal. However, that unit can handle 4 miners so deploying them would cost $48,000. The units offer power fallback and monitoring.

                  Comment


                    #39
                    Originally posted by suemarkp View Post
                    I'm not so sure the NEC stops at the wall receptacle. I've been spending the last few months, and probably the next year, assessing anything that "plugs in" for NRTL compliance. For things that are not NRTL listed, we can hire a field evaluation body to bless it, or we have some employees that have been designated as allowed to bless the item. This involves some NEC basics (guarding, grounding), and verifying the bonding of exposed metal with a bonding meter. This is being pushed by OSHA and has actually been a Washington State rule for quite some time. It is just difficult to enforce, as the electrical inspector is the only one who typically looks at utilization equipment, and cord-and-plug things are usually not there when the inspector shows up.
                    It kind of does yet kind of doesn't. If what is plugged in isn't the utilization equipment being served it generally needs to be listed for whatever purpose it is serving.

                    Like I said before you can't put several receptacles next to your service panel and then run extension cords to all your utilization equipment not in that vicinity, temporary purposes would be an exception.

                    I live for today, I'm just a day behind.

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                      #40
                      Originally posted by cottora View Post

                      Those would be ideal. However, that unit can handle 4 miners so deploying them would cost $48,000. The units offer power fallback and monitoring.
                      What is the power inlet plug on these miners C13 or C19? There are other PDUs that use larger plugs (typically up to 60A but those are expensive pin and sleeve type), and horizontal ones that take up less space. What seems different for you is your miner machines need a lot of power. Many servers only draw a few amps and have redundant power supplies (cutting power in half per supply until one fails), so a stack of them may need 30 C13's while the total load is around 30 amps. You may be on the cheapest path if each individual machine draws over 5 amps. It comes down to cost per outlet and whether PDUs save you anything over panelboard space, circuit breaker, cable runs, and the make up of each box.
                      Mark
                      Kent, WA

                      Comment


                        #41
                        Originally posted by ramsy View Post

                        Combined with fused PDU above, If NRTL labeling of 6-50 to L6-30 adapter is not counterfeit, NEC 240.21(B) may allow the tap to 6-50R on #6cu feeders per NEC Table 210(B)(3), 210.24, or perhaps >50A feeders per 210.18 Exception, 210.23(D).
                        Thats a welder adapter and its listing probably limits its use to that (similar to RV adapters)

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                          #42
                          Originally posted by kwired View Post

                          It kind of does yet kind of doesn't. If what is plugged in isn't the utilization equipment being served it generally needs to be listed for whatever purpose it is serving.

                          Like I said before you can't put several receptacles next to your service panel and then run extension cords to all your utilization equipment not in that vicinity, temporary purposes would be an exception.
                          And that is the problem. We have labs with computer and audio/video type equipment with no NRTL listing (typically 20% of things are not NRTL listed). Many items have CE markings, but this self certification of conforming to EU standards is not an acceptable mark in the US. Many things also have the RU label (UL Recognized component). But that by itself is also no good. We also have a bunch of custom made things because you can't buy them (we do R&D work), plus items used in labs that when deployed in the field are exempt from the NEC (e.g. aircraft avionics that is typically approved under FAA test/experimental processes or military acceptance).

                          Many of the NRTL rules fall back to UL requirements, and the NEC basically regurgitates many of the UL standards. I find the NEC easier to look through than all the UL standards just because the scope of UL is so wide and I have much less experience reading those documents.
                          Mark
                          Kent, WA

                          Comment


                            #43
                            Originally posted by cottora View Post

                            800 Total on all shelves running the entire 30'. Google "miner container"
                            I would be curious how the numbers compare using 3x 84 space panels, 100x 6-50R and 100x sketchy adapter vs 10x 84 space panel & 400x 6-20R duplex.

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                              #44
                              Originally posted by Todd0x1 View Post
                              100x 6-50R and 100x sketchy adapter vs 10x 84 space panel & 400x 6-20R duplex.
                              Sketchy adapter missing fused load, or fused-plug strip, violates both NEC 240.21(B) feeder tap rule, and Equipment Listing requirements (NRTL).

                              Underfloor channel running length of container may be a wireway, see NEC 376. Up to 30 CCC's can fill 20% of wireway without conduit derating, and avoid tap rules if desired. All you need is wire, receptacles, and removable cover for wireway channel under floor.
                              Roger Ramjet NoFixNoPay

                              Comment


                                #45
                                Originally posted by ramsy View Post

                                Sketchy adapter missing fused load, or fused-plug strip, violates both NEC 240.21(B) feeder tap rule, and Equipment Listing requirements (NRTL).

                                Underfloor channel running length of container may be a wireway, see NEC 376. Up to 30 CCC's can fill 20% of wireway without conduit derating, and avoid tap rules if desired. All you need is wire, receptacles, and removable cover for wireway channel under floor.
                                Even with 30 CCC's in wireway, youre talking about 800 CCCs so thats alot of wireway. Then I was thinking what if a prefab shop made up 4S boxes with 12/4 MC and two 6-20R duplex in each. That would be 200 runs of the 12/4 MC cable.

                                This power density here is insane (I have no idea how this would get cooled) something like 3kw per square foot. And what are the fault currents going to look like? Seems like the electrical gear will take up more space than the load.

                                I am very interested to see how this turns out.

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