securing conduit at breaker

[astrojeff]

I have a 100 amp subbreaker with no circuits on it yet that sits against a block wall adjacent to the crawlspace. I want to run some new circuits through the crawlspace to the kitchen. My main breaker (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 conduit and prevent sharp edges. But the subbreaker 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.

If I run the conduit 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 conduit hanging out of the pipe and it off a breaker? What's the correct way to do this? Is there an NEC code for this? The wire feeding the subbreaker 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?

[Doug Miller]

Your consistent use of incorrect terminology (e.g. repeatedly writing breaker when you mean panel, and conduit when you apparently mean cable) does not fill me with confidence that you understand what you're doing well enough to do it safely. Please visit a library or home center store and get yourself a book on basic residential wiring before you burn your house down.

[astrojeff]

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:

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.

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? What's the correct way to do this? Is there an NEC code for this? 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?

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.

[astrojeff]

Rest assured, I have a book on residential wiring, and I am a visual thinker, so although I am a little slow on matching the correct words to the objects--but I DO know the difference, but I apologize for the confusion and not being more careful. And I have a friend who is helping me with the project who has quite a bit of experience, though he has not worked on this type of panel before. I was asking the group because I couldn't find it in my 2 books. But I will continue to search more books if nobody will answer me due to my ignorance.

-thoroughly humbled

[Doug Miller]

That helps a lot.

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.

Yes, there is -- hence the six inches rule.

(described above)

Yes, as long as you don't exceed the limit for that conduit.

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.

[astrojeff]

How does this sound?

At the local electrical store with help from an electrician, I got 2" LB and conduit to run from the subpanel stub out up the block wall to the floor joists above--I also got 2" brackets to secure to the wall.. Then I got a PVC screw adaptor, locknut and bushing to attach to a 6" metal box with knock outs, which I will secure to a joist and use romex connectors/clamps to run the cable out and then I'll staple the cable along the joists the rest of the way to the kitchen wall, starting at six inches from the box.

Unless there's more I'm missing, thanks!

[Doug Miller]

Perfect.

You're welcome.