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Thread: Shop wiring: Having 120VAC and 240VAC circuits in the same conduit??

  1. #1

    Default Shop wiring: Having 120VAC and 240VAC circuits in the same conduit??

    I was talking with my friend the other day about wiring his shop. He wants to install a series of 120VAC and 240VAC outlets around the walls. The 120VAC outlets would be on single breakers, and the 240VAC outlets would be on double breakers.

    The wiring will be run in PVC conduit with a tee above each outlet.

    Is it OK to have both voltages in the same conduit? Would it be safer to have a separate run of conduit for the higher voltage outlets?

    Roger

  2. #2
    Join Date
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    Yes it is OK to run both Voltages in the same conduit. In fact, in a 220 circuit you simply have two 110 Volt circuits that are out of phase and thus produce the 220. No problem running any combination of 110 and 220 in the same conduit.

    As for a tee above each box, why? There are practical limits to the number of 90 degree turns that you should/can make in any conduit run. Generally a total or 270 degrees is considered the max for easy pulling and many like to keep it to only 180 degree. A tee would add an additional 90 degrees for no real reason. Usually the conduit goes in one side of the box and out another (or the same one). You do need to consider the number of wires in each box, but if it gets too crowded, larger boxes can be used.

    I am not a fan of PVC conduit. Especially in a shop. I like to run EMT but still include a ground wire for each circuit. I never depend on the conduit for the ground connection: I have seen too many places where the conduit was damaged and continuity was lost. But the hot and neutral wires were still intact: hot circuit but no safety ground and the users have absolutely no idea that this hazard even exists. This is a great and unacknowledged safety hazard, IMHO.
    Paul A.

    Make it fit.
    You can't win and there is a penalty for trying!

  3. #3
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    Aug 2008
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    Lomita, SoCal, USA
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    Default 120V circuit is 1/2 of the 240v circuit

    Unless your friends shop has 3 phase power, the 240vac circuits are just 2 120vac circuits, 1 from each hot bus in the breaker box. The maximum measured voltage between any hot wire and ground or neutral will only be 120vac. As long as you don't exceed the wire fill limits of the conduit, it doesn't make any difference.
    Davis

    "Nothing is impossible for the man who doesn't have to do it himself"

  4. #4

    Default

    I am not a fan of PVC conduit. Especially in a shop. I like to run EMT but still include a ground wire for each circuit. I never depend on the conduit for the ground connection: I have seen too many places where the conduit was damaged and continuity was lost. But the hot and neutral wires were still intact: hot circuit but no safety ground and the users have absolutely no idea that this hazard even exists. This is a great and unacknowledged safety hazard, IMHO.[/QUOTE]


    The National Electrical Code has required a seperate ground wire in conduit runs for over 10 years that I know of because of the problem you related.

  5. #5
    Join Date
    Mar 2001
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    Nottingham, England
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    Slightly different over here as we have no 110 volt and no out of phase 240 volt.

    We have three phase, in between any two phase is 440 volts, in between any phase and neutral is 240 volts.

    Old colours were red, yellow blue for phases, black for neutral and yellow/green for earth. Been this way since the first 3 phase mine was discovered in North Yorkshire.

    Problem now is with all this EEC, UE and PC crap they keep swapping the colours. From red, yellow, blue they moved onto all black including the neutral with a coloured tag on the end of red, yellow blue ?? WTF ??

    After a few remarkable explosions, fires etc they then said we had to change to continental wiring of brown, black, grey with a blue neutral which still catches the unwary out and many offices have had their equipment blown up when linking new to old and the printer get stuffed across 440 volts.

    Many small companies stick to the red, yellow, blue and claim 'existing wiring'

    good Tiffiepedia link here.

    http://en.wikipedia.org/wiki/Three-p...er#Color_codes

    Note how many countries still use red, yellow, blue.

    Last place I worked at as employed we had three rings in the trunking, usual red, yellow, blue and two extra rings of 3 wires all purple and 3 all brown. The brown were 110 volts at 200 Hz and the purple were 240 volts at 400 Hz for the high speed Persch <sp> motors on the wood boring machines.

    These were supplied from two separate motor generators in the shop.

    .
    .

    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.




  6. #6

    Default

    My concern was that you'd have to switch off two breakers (one single and one double) to kill the power to the wiring in the conduit.

    Obviously, that's not a valid reason to run two separate conduits.

    Roger

  7. #7
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    The only wiring you CAN NOT run together with power is Signal Ckts (Fire Alarm) as long as they are all 600v insulated wiring (THHN)

    You can even run 24 volt DC or AC in the same conduit - but you can not terminate them in the same box (they need their own seperate box)

    BUT - you CAN NOT run PVC inside the walls. And less then Schedule 80 is not allowed above ground (exposed) at elevations of less then 8'. Considered a zone for Mechanical Danger.

    For Residencial Installations all 2 pole breakers (240v ckts) must have a single handle / trip mechanisim. 2ea 110 receptical ckts can share a nuetral (multi-wire ckts) but the breakers supplying them must have the handles tied together (factory) so you can not shut off 1 with out shutting off the other.

    Tip of the Week: Use HVCR rated Breakers for Motor Loads

  8. #8
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    winchman, you would have seperate breakers for the 220 and 110 circuits. You shouldn't have, say, a 220 breaker with one circuit of receptacles one one pole and another circuit of recepticles on the other pole. I don't think it is acceptable anywhere.

    The PVC conduit is ok in residential use for surface mount but for commercial it has to be metal conduit. I like the PVC because it's easy to work with and if you use a heat gun you can make bends anywhere you want them exactly like you want them so easy it will make your head spin.

    What ever you do run conduit larger than you will ever need if you run multiple circuits through it. It makes it easier to pull the wire and add stuff later. It's interesting the new combination of dirty words one can come up with pulling wire through a multiple bend run with marginal size conduit.
    Last edited by Carld; 02-21-2009 at 10:31 AM.
    It's only ink and paper

  9. #9
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    Default

    Quote Originally Posted by Carld
    winchman, you would have seperate breakers for the 220 and 110 circuits. You shouldn't have, say, a 220 breaker with one circuit of receptacles one one pole and another circuit of recepticles on the other pole. I don't think it is acceptable anywhere.
    Just built a new house and the kitchen had to be wired with 220V into each box. Then the box was split so that each outlet ran on a different breaker. The two breakers were pinned together in the breaker box.

    Maybe this is a Canada thing?

    Andrew

  10. #10
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    Was that one 220 circuit just in that receptacle box only and not fed to other outlets?

    By the box split I assume the jumper on the receptacle was removed and each socket had a seperate circuit? I can see that posibility if one recptacle outlet powered a refrigerator and the other outlet powered a freezer. But I don't understand why they had to be pined together.

    I'm sure the code is different in Canada and the USA.
    It's only ink and paper

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