Beefing up an old system

[giddonah]

Most of the wiring in the house I'm working on is BX. Some of it is grounded through the cable, some pretty well, some not so well, and some not at all. I can access all the wiring on the second floor through the attic. I'd like to ground everything and add a couple circuits (eventually add a/c to the second floor through the attic). Brand new 200A panel just installed in the basement with plenty of room for new breakers.

I was thinking of just putting a 60A panel in the attic, but they only have 2 spaces? I think I'd like more room than just 2 spaces. 100A panels have 6 spaces which would be nice, but seems like overkill. So, what about feeding the 100A panel with 60A or so? Just feed it with 100A anyway?

I'm thinking of bringing the power across the basement ceiling, out into conduit, up the outside 25' or so and into the attic. I'm thinking I probably need to do conduit the whole length.

I won't rewire the whole thing right away. Right now I just need a good 20A circuit for a bathroom gfci, and ground some of the bx. In the future, we're hoping to turn the place into law offices, and a panel in the attic would help with that.

Am I crazy? Should I just run 3 or 4 12/2 up there?

[Sparks]

Being that you may be turning the place into law offices, I would opt for the sub-panel. Office equipment sometimes need dedicated circuits, isolated grounding, and of course the people who work in law offices and offices in general are NEVER happy with the original wiring layout and always want new circuits installed, receptacles moved, lighting upgraded, you name it. Office employees are never content with what is originally there, believe me, I speak from experience. Having a sub in the attic directly above the offices would certainly make things easier. Of course, pleasing the tenant is optional but usually in the landlords best interest obviously. Go nuts with cat 5e or 6 as well because this is also always an issue for office employees, the more ports, the better. I would go with a 100 amp sub if offices were planned, you can get 12 space panels in 100 amp, or more if needed. Also the more spaces the better. Can you find a chase inside the building so you wouldn't need an outside run? You should be able to run SER cable from the main to the sub inside the building but outside would work as well, whatever is easier and cheaper. Remember just one of those little portable heaters that every office employee must have under their desks in the winter usually pulls about 1500 watts. Almost all women have these under their desks, at least in NY state anyway. Just some food for thought.

[giddonah]

There is one vertical run in the house. It's for the plumbing stack though. I wasn't sure if I could run wires that close to the stack. I figured an outside run would provide the fewest issues.

The second floor would have space for 5.5 offices and two bathrooms. I was thinking that 100A would be overkill, but a 12 space? I guess it would be better than running out of room.

So what would you use for the conduit? I was thinking of ent for the indoor sections and ridgid for the outside. Should I use liquid tight flexible? PVC? I'm going to run it on the back corner of the house where nobody will ever really see it, so aesthetics are not an issue.

[Sparks]

You're much better having extra capacity than under with offices, one copy machine sometimes requires a dedicated circuit. If your running pipe outside you could go with rigid, but it's tough to work with, you could go with emt as well, just make sure you use the new style rain tight fittings, they've changed the requirements recently. PVC is ok, but it sags badly when the sun hits it so keep that in mind if the run turns horizontal and support it well. Personally, I would try to find an inside path, it's usually easier and less expensive using SER. Sealtight would also work but some AHJ's enforce the 6' rule, see NEC regarding this. I would use the same raceway inside and out, it's usually quicker and easier. EMT, PVC, RIGID or Ser would be fine. I've never used ent, not very popular around here.

[giddonah]

Ok. That's all good stuff right there.

Can I run SER right next to the vent stack?

[Sparks]

I don't think the code prohibits it, but I would check your new book just in case. I would think as long as you don't expose it to physical damage you would be ok. If you're having the work inspected, call the inspector to verify. Another possibility would be to run a 1.5 or 2" conduit from the main to a big J-box in the attic. You could run a lot of circuits through it and it would be simple to add more any time you wished. Without the expense of a sub-panel. You would just have to respect the de-rating rules dictated by the nec when more than 3 current carrying conductors are in the same conduit. This is done often as well, it's just whatever works best for you and the future plans for the building. If you opt for the J-box idea, just make sure you always leave a pull string in the run so you can add circuits with relative ease, and try to make the run as straight as possible with few bends, and lube the pipe with wire lube. Or just pull in new cable each time your tenant brings in another piece of office equipment that requires a dedicated circuit or an isolated ground, you have a few options, it's just depends on your anticipated future needs.

[giddonah]

Ok, I'll see if I can't get some conduit or something inside a wall or next to the vent stack. Sure would be nice to not have to go outside when it comes time to re-side. I'm with you on the pull string. I always leave one for every pull. It's saved me a few times.

I think I'm set on the panel. Now I just need to get run of conduit up there...

[giddonah]

The consensus on ECN is that there's no problem running the SER next to the vent stack. It started to sound like a stupid question after some of the responses. It's not even addressed in the code I guess.

So, 4-4-4-4-6 (http://www.essexep.com/electrical/products/building/pdfs/Type%20SE%20Style%20R.pdf)? Any argument for/against copper/aluminum? I seem to remember something somewhere about largest breakers should be at the top of panels, is that true?

[Sparks]

The largest breaker doesn't need to be at the top, but, sometimes depending on a lot of things, it somewhat reduces voltage drop on the busses under a heavy load. It's never a bad idea if it doesn't involve too much. Al. is much cheaper than copper of course, some cringe when al. is mentioned but around here it's used often for residential service entrances and feeders. Branch circuits, no way, ever. You just have to be careful as heck when you're stripping it as to not nick the conductors. I use a razor knife with a brand new blade and only penetrate the insulation enough so you can twist the remaining off with your fingers, so the blade never touches the actual conductor. Also, you need de-ox to apply to the conductor and the lugs, don't forget this. Al. will need to be upsized compared to copper, but this is all in your code book. I always torque the lugs a few times because the al. will compress slightly and you don't want that causing a loose connection in the future. I didn't think the ser would be an issue next to the stack but I've never had to run it that way so I never thought about it. Them guys are ok, harrassing newer members is one of the rules on that site. :lol:

[giddonah]

Ok, another thing (I'd call it "one last thing", but I'd probably end up a liar). So, I'm doing 4-4-4-6 copper (unless it's worth the trouble for the Al savings) SER. I ran the fish tape last night with a string, pulled the string out and I've got 50' from the main to where the sub will go. I'm isolating the neutral from the ground. So, what about support for the SER? 4-5' from main panel to the bottom of the chase, 20' give or take 1' to the top, and 20' or so across the attic to the sub location. Do I need support along the vertical run?

[giddonah]

They didn't have Cu though, so I got 2-2-2-4 Al SER. I have a 125A breaker to feed it, but I have to check again if I have to drop down to 100A. Anyway, I'm going to start this party tonight. They didn't know jack about the bigger cable and I didn't see anything to de-ox the Al. What do I look for?

[Sparks]

No de-ox? You may have to go to an electrical wholesaler I guess. Without going to the truck, I'd guess it's around a 12 ounce bottle. It's most definately a "must do". The NEC lists the minimum support intervals for the cable, but support it as well as you can with the proper size straps and if you can't find a stud to nail to you may have to install a few 2x4's here and there. Although, the nec considers "fished" cable to be supported if you can't easily do so, so keep that in mind as well.

[giddonah]

Ok, there's a couple supply houses around. I did get it in though. Not easy, but there it is, from the main panel to the attic. I'll hook it all up tomorrow. I got a murray 125A subpanel to match the main panel to make buying breakers easier. I moved the right hand side breakers down and put in the 125 top right. I also need to pick up a pair of clamp connectors for each end of the SER. I'll have this together in no time, all the hard work is done. Table 310.17 says XHHW-2 at 2 AWG will do 150A (144A with a worst case scenario temp correction, but who's counting), but the panel label says only to use the 60 degree ratings. Makes no sense. :roll:

Yeah, I saw the rules on fished cable, I have access during the vertical run to support it with a strap a one point at least though. This is going to work out awesome. Cost me ~$160 so far with four breakers to get things going.

[Sparks]

Use table 310.15 (B)(6) page 70-143 in the 02 book.

[giddonah]

It's the same in the '05 book. Why the discrepancy between tables? 2AWG Al XHHW-2 is good for 150A unless it's a "feeder"? That just sounds dumb. 100A is probably plenty, but being forced to drop down because of what the cable is called irritates me. What am I missing here?

Edit: I take it SER isn't single insulated. Ok, the extra insulation on SER cuts down on heat dissapation. I'll give. :?

[Sparks]

150 amps is for one single wire hanging in free air. Obviously much different than three current carrying conductors encased in sheathing. Heating effect being much greater in the latter. Does your sub have a main breaker or is it just a main lug panel. If it has a main, you may be able to use it as is. Just have to check and see what article supports it.

[Sparks]

I re-read your posts, the tap rules would only apply if your run was less than 25 feet, then you could get away with using the sub-breaker to protect the cable. Seems your run is too long, looks like you need a new breaker if you want it code compliant.

[giddonah]

It's a lug panel. I got a 100A breaker to feed it. No biggie. It's still pretty hefty. We'd have to get some pretty major equipment in here for it to get maxed out. Found the de-ox. I'm just slackin' right now. I need to go hook this thing up. :roll: :)

[giddonah]

Ok. I energized this thing, and wouldn't you know it, there were no explosions. No band playing. No fireworks. No hot girls in bikinis to present my trophy. No trip to the white house. And I'm not going to Disney Land.

I'm still extremely proud of it though. It looks pretty good, I'll post pics next week for the post-game. I threw the meter on it and I'm getting 240 across the lugs and 121 from each lug to the neutral. I put a 4-by receptical next to it and it tested good.

Many thanks to you Sparks for all your help with this.

[Sparks]

Any time Giddonah, get those pics posted so we can critique. Now if someone would just answer my question as to how to delete a post. :?

[giddonah]

Only moderators can delete posts in the thread they have moderator status in. :D

Edit: aparently, you also have a short grace period in which to make edits without it saying that you did, and delete a post. This goes for any thread.

[Sparks]

Right, I meant your own posts. It says you can edit or delete, I can't figure out how to delete even within a short time.

[Dormer_man]

Maybe if you can't delete it, you can edit it down to

"Tally-ho, mate" or something equally innoculous.

[giddonah]

Right after you post, look at the top right corner of the post. I see three buttons: "quote", "edit", and an "x"

Edit: Yup, there it is. But it's gone from my earlier post.

[giddonah]

Ok, this is weird. I posted in the flooring forum and I didn't get the "x" button right after posting. And the "x" is still there from my post last night above this one...


Edit: "x" is now gone from post above, and now I have one for this post.

[Joe Bartolucci]

Hi gidd

Did you file for a permit and have your work inspected? I strongly recommend this. Especially if this building will be used by the public.

If your going to do the work on your own you should always get the work inspected. This will give you the piece of mind that all is well and in case something happens you will be legally covered.

Just ask any lawyer what they can do to a person that is found liable.

Joe

[giddonah]

Oh brother :roll:

[giddonah]

I finally got up there with my iPaq. Not the greatest photo quality...

Let me know if you want a different angle or whatever. I should get one of the main panel...

[Sparks]

Looks good. There are a few things I will mention just fyi. Are those drywall screws supporting it? That would be a problem with some inspectors as they don't have necessary shear strength. I would have centered the panel just in case you needed to use the ko's on the right side, that way you would somewhere to support the romex. I would have used a offset die-cast nipple to your receptacle box, no problem either way, the offset just looks neater. Looks good though.

[giddonah]

Yeah, I was thinking of using other screwes, but the main panel is up with drywall screws, so I figured what's good for the goose...

I hadn't thought of using the right side ko's. I figued I'd take everything either through the top or the bottom. I'll have to remember that for next time. I also saw another box next to a main panel done with romex and clamps, so again, good for the goose... Plus, it's what I had in my bag. I thought you'd say something about the SER not being long enough. If I had really thought about it, I probably would have given them a loop before connecting, for extra room, but there's a little slack in the run if I need to stretch it.

Oh yeah, I saw that the main panel and another panel the same guy did for us don't have any de-ox on the Al. Should I pull them out and apply it?

[Sparks]

The loop wouldn't be necessary in this case. There's no reason for any extended length in a panel, it just takes up more space. The big thing is not having too tight of a bending radius so as to damage the wire but yours is fine. Sometimes with bigger wire it's very difficult to bend so a loop sometimes makes installation easier. The de-ox is important so I would make sure it was on all al. terminations in any panel. How are you going to de-energize the main service? Is there a disconnect upstream of the main panel? I wouldn't advise you to pull the meter with the main first turned off, but that's what I would do. I wouldn't advise anyone to try to do it live, no way, not unless the person is very experienced and is using all the right safety gear and insulated tools. One mistake and catastrophe as the current that would develop if there was ever a ground fault would only be limited by the primary fuses on the utility transformer. Probably, depending on how close the transformer is to the house, around 10,000 amps minimum. One more thing, make sure you go back in a while and re-torque your lugs, you'll be surprsied how much they will have compressed. I recommend re-torquing again in one year, they usually need it, believe it or not.

[giddonah]

There's an outside disconnect for one panel, but the big main I'm not sure. what about just applying with a q-tip? I just ran outside, there's no disconnect for the main panel. the meter has a utility tag on the latch. I probably could do it live, but I'm not sure I want to. So, what about just doing it with a q-tip? man, is it so damn hard for people to just do things right the first time...

This is why I roll my eyes at "licensed" work and "inspectors" in my area. It's such a joke. Maybe they just forgot and would have normally, but for a professional, they shouldn't forget. In another town I saw a panel with white wires used for hots on 240V circuits that weren't re-identified. My friend says they all do that. If I'm finding these problems, what else is wrong? [/rant]


What about a de-ox spray? the service drop isn't de-ox'd either (it drops into a box with lugs, then splits to two meters on either side). I'm sure there isn't any inside the meter boxes, but I can't get in there.

How much does it accelerate the oxidation not to have de-ox? How long until this causes a problem?

[Sparks]

Good question, I really don't know how long it would take to cause a problem. Around here, they make a big deal about de-ox, I wouldn't be caught dead without applying it to al. conductors. I don't think spray or a q-tip would work, you would have to get it between the surfaces of the conductor and the inside of the lug. You would still have to loosen the lug to do it right. Dangerous considering there will be virtually zero overcurrent or ground fault protection. Don't attempt it live.

[giddonah]

Well, that's a tough one then. Maybe I'll be letting you know how long it takes to cause a problem :lol: