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Posted by Doug Miller on February 8, 2007, 8:37 am
>
>
>I ask because I could not find it in a book yet--that's the point in
>the group, I thought? I'll look in more books, but I was hoping
>someone here could help speed the search process. Sorry I was
>careless with words (that happens when I only read this stuff and
>don't talk about it with pros--I know it much better than I say it), I
>do know the difference between conduit, cable, breaker, and panel; let
>me try to correct my question to avoid confusion:
That helps a lot.
>
>I have a 100 amp subpanel with no breakers on it yet that sits
>against a block wall adjacent to the crawlspace. I want to run some
>new circuits to the kitchen. My main panel
>(which is in an inconvenient wall to pull cable to) has metal
>knockouts and I am familiar with the use of romex cable clamps to
>secure the cable and prevent sharp edges. But the subpanel just
>has a short 3" dia. plastic pipe that terminates at the other side of
>the block wall. How do I secure the romex? My wiring book and home
>inspection book do not discuss this situation--they only say to use
>clamps to secure cable when exiting any box.
There's no requirement to secure cable when it's leaving a box through
conduit. There is, however, a requirement to secure the cable when it leaves
the conduit. You need to have a bushing at the end of the conduit as well, so
that there is not a sharp edge on which the cable sheath could be damaged.
So...
Put a threaded adapter on the end of the conduit, and screw a plastic bushing
down on the threaded adapter. Run your cables through the conduit, and secure
them to the structure within six inches of the end of the conduit. The easiest
way to secure romex is with approved cable staples, hammered into wood. Since
you have a block wall there, you may need to attach a board or piece of
plywood to the block wall first, to give yourself something to staple to, if
there isn't any wooden framing accessible within six inches of the end of the
conduit.
An alternative to attaching wood to the block wall is extending the conduit to
a point that's within six inches of existing wood framing.
>
>If I run the cable directly out the pipe and staple it to the joists
>about 1' above the pipe termination, there's nothing sharp to cut the
>wire, but isn't there a danger that someone could snag the loose
>cable hanging out of the pipe and it off a breaker?
Yes, there is -- hence the six inches rule.
> What's the
>correct way to do this? Is there an NEC code for this?
(described above)
>The cable
>feeding the subpanel is completely enclosed in the same type of PVC
>conduit running into the box--but I can't do this for multiple
>circuits running out, can I?
Yes, as long as you don't exceed the limit for that conduit.
>
>My friend, who is more knowledgable with wiring than I, is helping me
>(does that make you feel more comfortable?), but he has not worked
>with this type of panel before. He suggested we secure the cable to
>the block wall with those pipe clips/clamps (whatever you call them--I
>could draw you a picture, but I'd probably use the wrong word and get
>chastised) and some sort of masonry screw.
I may be mistaken... but I don't think that there is *anything* that is
Code-approved for securing NM cable ("romex") to the face of a masonry wall.
Either extend the conduit, or attach some wood to the wall.
--
Regards,
Doug Miller (alphageek at milmac dot com)
It's time to throw all their damned tea in the harbor again.
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