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gandalfthewise
Rewiring older home

My situation is similar to many I read about on this forum... an older home, wired without ground wires or modern stuff, that needs to be brought up to present standards. In particular, my house was built in 1951, wired with 1950's romex, generally 12/2.

I would like to replace the whole mess, one because I would like it to be grounded, and two because while most of it is OK, there are lots of boxes left open (too full), connections made outside of boxes, soldered wires, and an occasional piece of 14/2 spliced in. I have rewired other houses that I lived in before, but it has been awhile, and I am not familiar with whats available now and current code.

I have worked on a few outlets already. I can't use the old wire to pull new wire in its place as it is well stapled to the studs along the way. I have been cutting off the old wire and removing the old boxes and replacing them with new old work boxes, connected with 12/2 wg NM cable and making all the connections in junction boxes in the attic. Below are some question about things I am not sure about:

  1. I am using Carlon plastic ceiling fixture boxes with lids as junction boxes in the attic. They are 20.5 cu in, which I think means I can fit 4 12/2 cables into the box. Correct ?
  2. Is there any approved method of splicing 2 cables together without a box ? I saw something used on the TOH show when they were building the prefab timber frame house/barn to connect wall sections together, but it was not discussed.
  3. There is a rule that plastic wall/device boxes do not require a wire clamp if the wire is stapled within 8” or so of the box. I assume this does not apply to my attic plastic junction boxes, and I will need some kind of clamp where the wires enter the box. I have found a plastic snap in clamp rated for 2 cables in a 1/2” knockout, but want to make sure it does not decrease the wire capacity of the box. Is a clamp required and do these plastic clamps decrease the capacity ?
  4. I assume there is no requirements at all to support the wire inside wall cavities where I have fished the wire into the wall. Clamp it at the box and staple it in the attic close to the hole and that is good enough. Correct ?
  5. I am concerned about burying all the attic junction boxes that I put in with insulation. For now I am attaching them to vertical supports or to rafters so that they will be above the level of the insulation that I will add after this is done. That will make them “visible” after the insulation, but accessible only with difficulty. Is that required ?
  6. I am adding some new outlets where I need them, but not trying to meet the 6 foot rule where it does not seem needed (I have some outlets that are just a litte bit more then 4 feet from a door, and if I added a new one the old and the new would be quite close.) Am I required to do more ? At what point do I have to meet new code on the whole house ?

Thanks in advance..

KKelly
Re: Rewiring older home

Answers by number...

Question 1: 12/2 isn't normally or reasonably used for common wiring in residential usage and it's not reasonably used in residential because no residential quick connects will fit it. But, you'll need to check with your local building codes to confirm what's required. Some structures, mostly former commercial ones, do require 12 gauge. 14/2 is common. Buy an “Ugly” book at your local hardware store ,(no, I'm not making that name up) it'll tell you all the codes you need to know.

Question 2: There is no approved method that I've ever heard of for splicing anywhere without a box.

Question 3: Any romex into a box needs to be stapled within 8” in my region, but, again, you'd want to check local codes.

Question 4: In my region, horizontal runs don't require fasteners but any adjacent vertical runs do within 8” of the hole in the stud and within 8” of the box, no exceptions. It's one of those things that does change by region but hardly. If you're a homeowner electrician, be particularly code compliant.. They'll nail you for pretty much anything.

Question 5: Can't bury a box in anything. It must be exposed and securely fastened.

Question 6: Inspectors normally look at the six foot rule within reasonable limits. If it doesn't make sense to put an outlet at a location, they rarely expect you to. As to the second part of that question; New wiring is always required to conform to all recent codes. There is no grandfathering rule for electrical.

Electrical codes vary by region so always check your local codes. And, an online forum is a great place for advice but it's no subsitute for building codes.

NEC
Re: Rewiring older home

1. If I understand the question correctly, yes.

2. Take a look at this:

http://www.code-elec.com/userimages/Tyco NM connectors.pdf

NEC 334.40 (B) Tells us:

"(B) Devices of Insulating Material. Switch, outlet, and
tap devices of insulating material shall be permitted to be
used without boxes in exposed cable wiring and for rewiring
in existing buildings where the cable is concealed and
fished. Openings in such devices shall form a close fit
around the outer covering of the cable, and the device shall
fully enclose the part of the cable from which any part of
the covering has been removed. Where connections to conductors
are by binding-screw terminals, there shall be available
as many terminals as conductors."

These are common in modular homes and are what you saw used.

3. Not sure what you mean. Most Carlon boxes have a plastic spring clamp at the cable opening and if you are in the attic I would think the cable could be stapled to the framing.

4. Correct, fished cables are not required to be supported.

NEC 334.30 (B)
"(B) Unsupported Cables. Nonmetallic-sheathed cable
shall be permitted to be unsupported where the cable:
(1) Is fished between access points through concealed
spaces in finished buildings or structures and supporting
is impracticable.
(2) Is not more than 1.4 m (41⁄2 ft) from the last point of
cable support to the point of connection to a luminaire
or other piece of electrical equipment and the cable and
point of connection are within an accessible ceiling."

5. Here is what the NEC says about access.

"Accessible (as applied to equipment). Admitting close
approach; not guarded by locked doors, elevation, or other
effective means.

Accessible (as applied to wiring methods). Capable of
being removed or exposed without damaging the building
structure or finish or not permanently closed in by the structure
or finish of the building.

Accessible, Readily (Readily Accessible). Capable of being
reached quickly for operation, renewal, or inspections
without requiring those to whom ready access is requisite
to climb over or remove obstacles or to resort to portable
ladders, and so forth."

6. That is really a question for your local building department. Where I am it is usually "50%" but I am not in the house rewiring business. I will ask an electrical inspector friend on his take but it may take him until he is back in the office to reply.

Again, your local codes may vary so it's better to check sooner than later.

NEC
Re: Rewiring older home

I took some time to go back through the NEC regarding your question #1 and I just might be wrong....... I never have been very good at box fill calculations.

NEC table 314.16 (B) allows for 2.25" for #12. 8 conductors would be 18".

NEC 314.16 (B)(5) allows the grounding conductors to count as 1 which would take you to 20.25" which would tell me you are good.

But then there is this:

314.16 (B)

"(2) Clamp Fill. Where one or more internal cable clamps,
whether factory or field supplied, are present in the box, a
single volume allowance in accordance with Table 314.16(B)
shall be made based on the largest conductor present in the
box. No allowance shall be required for a cable connector with
its clamping mechanism outside the box."

That would lead me to belive that the built in spring tab clamps on a Carlon box would need to be counted as one and would mean you would be over filled by 1.75"

In all honesty I do not know.

Ernie_Fergler
Re: Rewiring older home
NEC wrote:

I took some time to go back through the NEC regarding your question #1 and I just might be wrong....... I never have been very good at box fill calculations.

NEC table 314.16 (B) allows for 2.25" for #12. 8 conductors would be 18".

NEC 314.16 (B)(5) allows the grounding conductors to count as 1 which would take you to 20.25" which would tell me you are good.

But then there is this:

314.16 (B)

"(2) Clamp Fill. Where one or more internal cable clamps,
whether factory or field supplied, are present in the box, a
single volume allowance in accordance with Table 314.16(B)
shall be made based on the largest conductor present in the
box. No allowance shall be required for a cable connector with
its clamping mechanism outside the box."

That would lead me to belive that the built in spring tab clamps on a Carlon box would need to be counted as one and would mean you would be over filled by 1.75"

In all honesty I do not know.

We all struggle with fill box calculations. Please remember blue PVC boxes will have that info stamped inside of the box. Or just buy the deepest box possible and remember to add in the device when tallying up your numbers.:cool:

Moon Over My Hammy
Re: Rewiring older home

A plaster ring can add space for your fill. So can the canopies if they are rated. Plastic boxes hold heat from lights and ambient temps from attic.

Can use a blank cover on junction boxes to close but still have accessibility.

Wouldn't re-use old NM or new NM-B (dry locaiton only cable is still 60C even if wires within are 90) in open vented attic could have condensation within the cable jacket, NMC-B maybe depends on temperatures in attic.

gandalfthewise
Re: Rewiring older home

I am using Carlon plastic ceiling fixture boxes with lids as junction boxes in the attic. They are 20.5 cu in, which I think means I can fit 4 12/2 cables into the box. Correct ?

So the question is, since these boxes have no built in clamps, are the snap in plastic clamps considered internal ? They are certainly almost all on the outside and take little or any space inside the box. the boxes I was using (Carlon A615DE) are marked 20.5 CU, and without any kind of wire count number.)

2. Take a look at this:

http://www.code-elec.com/userimages/...connectors.pdf

This would help a lot, but from reading about it, it appears to be approved for factory installation, etc, so I doubt if I could get away with using it to repair previous owners inline splice without a box.

Question 3: Any romex into a box needs to be stapled within 8” in my region, but, again, you'd want to check local codes.

Yes of course, but the question is when is stapling within 8" good enough and when do you have to staple within 8" plus use a clamp on the box for NM cable ?

4. Correct, fished cables are not required to be supported.

Thanks, that was what I thought as well.

Question 5: Can't bury a box in anything. It must be exposed and securely fastened.

Accessible (as applied to wiring methods). Capable of
being removed or exposed without damaging the building
structure or finish or not permanently closed in by the structure
or finish of the building.

Sounds like it has to be visible, mounted well, but Its ok to have to move a big pile of insulation to get to it. Guess I will keep doing as I am and mounting boxes up high enough to keep them out of the insulation.

Thanks for all the help.

NEC
Re: Rewiring older home

If you are using these boxes then fill would be ok since the clamps would be outside of the box.

gandalfthewise
Re: Rewiring older home

That certainly looks like them.

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