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  1. #1
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    Default Off set p-trap, what else?

    Kitchen double sink with dishwasher drain. I know the dishwasher drain (flex line) is incorrect. Otherwise I get confused.

    This whole drain pipe configuration just bothers me, especially with the p-trap being off set so far back from the sink tailpipe. But I'm having trouble understanding the code, and how to report it. Suggestions welcome.

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  2. #2
    Join Date
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    Default Re: Off set p-trap, what else?

    That basically amounts to a running trap, the inlet to the trap is about the same height as the outlet from the trap. Running traps used to be specifically prohibited, however, now the only reference is inferred by this:
    - P3201.1 Design of traps.
    - - Traps shall be of standard design, shall have smooth uniform internal waterways, shall be self-cleaning and shall not have interior partitions except where integral with the fixture. Traps shall be constructed of lead, cast iron, cast or drawn brass or approved plastic. Tubular brass traps shall be not less than No. 20 gage (0.8 mm) thickness. Solid connections, slip joints and couplings shall be permitted to be used on the trap inlet, trap outlet, or within the trap seal. Slip joints shall be accessible.

    Now the code only vaguely addresses running traps as running traps are not of standard design.

    Running traps are likely to self-siphon the trap water seal out, no or insufficient trap water seal and sewer gases will pass through the trap unimpeded.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  3. #3
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    Default Re: Off set p-trap, what else?

    It seems that the j-fitting from the right sink to the left sink is ok, but then there is a second j-fitting at the left sink tailpipe. I would have thought that with the general requirement for gentle curves and turns (not sharp 90 degree changes of direction), two j-fittings in a row would not be allowed.

    I guess what I was looking for was some sort of code that required the p-trap to be present directly below the tail pipe.

    This is a new relatively new guest house. The 1997 main house had several nasty plumbing items that I was able to see including reverse direction wye fittings, too short of a standpipe for the washing machine drain, an S-trap under every sink, and only one small vent pipe that I could find. And, the owner used sched 40 PVC for the cold water supply lines (CPVC for hot). So when I finally got to the guesthouse, I was expecting more bad stuff, but all I could do was scratch my head at the plumbing under the kitchen sink.

    BEST of all was running the water supply line for the guesthouse through the attic of the main house, through the attic of the unheated, uninsulated garage, to the exterior before running a few feet underground, then again up through the attic of the guesthouse, and a 90 degree CPVC ftting in the middle of a PVC pipe run. Keep in mind - this is Montana, where plumbers get to fix all sorts of frozen plumbing. Obviously a summertime guest house only.


  4. #4
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    Default Re: Off set p-trap, what else?

    Quote Originally Posted by Terry Beck View Post
    I guess what I was looking for was some sort of code that required the p-trap to be present directly below the tail pipe.
    That is where the trap should be, yes. Again, though, it gets down to the standard design of traps and that statement is vague without a document to reference.

    Even the IPC, which addresses plumbing more in-depth than in the IRC, no longer specifically references running traps, and instead references:
    - 1002.2 Design of traps. Fixture traps shall be self-scouring. Fixture traps shall not have interior partitions, except where such traps are integral with the fixture or where such traps are constructed of an approved material that is resistant to corrosion and degradation. Slip joints shall be made with an approved elastomeric gasket and shall be installed only on the trap inlet, trap outlet and within the trap seal.

    I'm not sure that the connections in your photo, nor the trap in your photo, would meet the requirements highlighted with underlining and bold above.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  5. #5
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    Default Re: Off set p-trap, what else?

    Thanks Jerry. Never heard the term 'running trap' before. Makes sense


  6. #6
    Garry Blankenship's Avatar
    Garry Blankenship Guest

    Default Re: Off set p-trap, what else?

    Keep it comin Gents. This stuff is inadequately understood by yours truly. I did notice a N/M cable fitted onto a male cord cap, ( assuming the dishwasher power ? ). It is one of those "works OK, but not legal" situations. I am unwilling to hunt down chapter & verse, but pretty confident N/M cable cannot be terminated w/ a cord cap.


  7. #7
    Stephen G's Avatar
    Stephen G Guest

    Default Re: Off set p-trap, what else?

    Quote Originally Posted by Jerry Peck View Post
    - - Traps shall be of standard design, Traps shall be constructed of lead, cast iron, cast or drawn brass or approved plastic. .

    Is this an old manual JP? They still use lead, even for the drain???


  8. #8
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    Default Re: Off set p-trap, what else?

    Quote Originally Posted by Stephen G View Post
    Is this an old manual JP? They still use lead, even for the drain???
    Nope - that was from current code.

    Lead? Still in the code, not sure if anyone uses it anymore?

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

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