[Josh White]

I've had a helper's license for a few years, and I work with my old man when I'm not in college. I'm an English and History double-major, so bare with me if I'm not technically inclined. Anyway, I have a few questions that, no matter how hard he tries, my father cannot answer fully. Perhaps you guys can help. First, what is the point of a crimp sleave? Wouldn't twisting your ground wires two or three times offer a better connection? Second, why can't you run all your homeruns through a single PVC pipe into the breaker panel, especially if they are secured on the other end of the pipe? There are some instances where this would be very convenient. And can you tape the stranded wires from a GENTran in order to make the panel neater? They make such a mess out of an otherwise "workmanlike" panel. Another question is why we only have to use arc faults in bedrooms. Wouldn't kitchen or bathroom circuits be more appropriate? That's where all the load is. Oh, and would arc fault breakers make aluminum romex safe? Okay, and one last question...why do you bond the grounding and grounded conductors in the main breaker panel? Isn't the unbalanced current suposed to go back to the transformer? Why then not keep the grounding conductor separate all the way?

 

[mdshunk]

Holy cow, Josh. I'll take these one by one.

I've had a helper's license for a few years, and I work with my old man when I'm not in college.

That's fantastic.

I'm an English and History double-major, so bare with me if I'm not technically inclined.

Now you're losing my respect. :cheesygri

Anyway, I have a few questions that, no matter how hard he tries, my father cannot answer fully. Perhaps you guys can help.

Did your Dad say somthing like, "Go ask your mother"? That's usually what Dad's say when they don't know the answer.

First, what is the point of a crimp sleave? Wouldn't twisting your ground wires two or three times offer a better connection?

Well, some guys have this mistaken impression. Some form of mechanical connection is required per NEC§110.14(B). A twisted only connection is not permitted by the code. You can use a crimp sleeve (my preference) or a greenie wire nut or a regular wire nut or anything else identified for this purpose.

Second, why can't you run all your homeruns through a single PVC pipe into the breaker panel, especially if they are secured on the other end of the pipe? There are some instances where this would be very convenient.

You can, but if the conductors are bundled in this pipe for more than 24", then you have to "derate" the conductors due to bundling. This would turn the required 20 amp circuits for the kitchen and bathroom into 15 amp circuits (for example) causing a code violation.

And can you tape the stranded wires from a GENTran in order to make the panel neater? They make such a mess out of an otherwise "workmanlike" panel.

Sure, or you can use zip ties. Just don't bundle them super tight. Just enough to tidy things up a bit would be fine. Remember the bundling derating that I just talked about.

Another question is why we only have to use arc faults in bedrooms. Wouldn't kitchen or bathroom circuits be more appropriate? That's where all the load is. Oh, and would arc fault breakers make aluminum romex safe?

That's where the code makers have us using them now. Apparently people are burning up in their sleep all over the country. I don't know. No, they wouldn't offer much help on AL connections, because AFCI's in their current incarnation only detect parallel arcs. Typically a bad AL connection is a series arc fault, which this generation of AFCI's does not detect. By January of 2008, AFCI's are mandated to be of the combination type, which will detect parallel as well as series arcs.

Okay, and one last question...why do you bond the grounding and grounded conductors in the main breaker panel? Isn't the unbalanced current suposed to go back to the transformer? Why then not keep the grounding conductor separate all the way?

The bond connection there is just so all the equipment grounds can complete the circuit back to the transformer (via the service entrance neutral) in the event that a fault develops anywhere to ground. If the ground was not bonded here, if a fault to ground developed, it would have no where to "flow" until you touched something. Then, it would flow through YOU. With the bond, if a ground fault develops, it will flow back to the transformer and pop the circuit breaker.

Hope that helps some.

 

[bergenbldr]

Md,interesting fact about the paralell series arc,s .I was going to change out my own breakers for arc faults but now thinking i should wait until new versions are availible. Any idea when change over will be.

 

[luckyshadow]

You have to derate if you bundle the wires or not. Derating comes into play as soon as you have more then 3 current carrying conductors.

 

[mdshunk]

You have to derate if you bundle the wires or not. Derating comes into play as soon as you have more then 3 current carrying conductors.

Well, you don't derate for nipple fill, do you? A nipple is 24" or less, which I why I mentioned that he can sleeve the romexes in a piece of pipe into the panel less than 24". This is commly done.

 

[mdshunk]

Any idea when change over will be.

I suspect that the combination type AFCI's will start to show up in about a year and a half last I heard. Like anything, they'll suck for a few years. I wouldn't be in any hurry to jump on board until someone is making you. Remember how bad GFCI receptacles were when they first showed up in the late 70's?

 

[Speedy Petey]

You have to derate if you bundle the wires or not. Derating comes into play as soon as you have more then 3 current carrying conductors.

Besides that, we derate from the highest temperature column so derating only has an effect after 9 conductors, which for NM is (4) two-wire cables.

 

[luckyshadow]

I stand corrected gentlemen. I miss read the reply. I read it as sying only derate if bundled. :

 

[jbfan]

MD Great explainations!