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Line and low voltage in a zone valve

Tony_8 Member Posts: 608
is a no-no. That applies to any conduit. Line voltages of any over 115 to ground can be in the same conduit, but low voltage can't be there w/line voltage. I especially wouldn't use anything that could be mistaken for low volt because it was the same type/size as line volt. Years ago I ran into an old system w/line voltage to the end switches w/18 AWG stat cable switching on the circ directly w/the boiler maintaining limit temp all the time, got nailed good, hurt for days... Changed it to low volt end switch, installed a switching aquastat, saved the HO a ton of money and me the fear of another man not being lucky as me..


  • We dont use them often

    But when we do , we try to neaten the wiring in the Honeywell zone valves . We use BX from the valve to a junction box . Is there any problem using line voltage for the end switch , and mingling it in the same BX with the low voltage wire for zone valve motor ? We do use 14 gauge wire for each - the end switch and low volt motor .
  • hot_rod
    hot_rod Member Posts: 21,880
    Same here

    Tony. Both times it was stat wire to a LWC. Once in a dimly lit basement, the other in the middle of the night in a Spanish Church responding to a cracked boiler. (LWC was missing its wiring cover in both cases.) Zzzzzzaaaapppp! Makes for a numb arm.

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  • I was told...

    that as long as the insulation is rated for 300 volts that you can mix high and low voltage. Don't think I'd recommend it, but I think the code approves it.

    Obvioulsy, you wouldn't want to do it the way they did it using stat wire, but I think it can be done (told this by an inspector/instructor.

    I treat ALL wire as if it has high voltage in it, because as far as I'm concerned, it IS high voltage compared to my bodies voltage. I've been nailed pretty good with 24 volt before too.

  • Tom M.
    Tom M. Member Posts: 237
    Noy my area of expertise but

    I think that multiple voltages are allowed if all the conductors are rated for the highest voltage present in the conduit or enclosure. I think this is why boiler controls have a divider between the T-T terminals and the high voltage terminals. Also, single zone circulator relays have a removable divider to isolate the 5-6 terminals when used for low voltage. With the divider in place, this is a separate enclosure and tstat wire can be used.
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