ECN Forum
Posted By: bot540 Residental homerun - 09/15/04 10:48 PM
Do you think its a bad idea to use a 1900 and extension box for second floor homeruns? The guy I used to work for would often do this in two or three of the switches so he could come out the top of it 6 times instead of 3.
Posted By: hbiss Re: Residental homerun - 09/15/04 11:31 PM
I have never had the need to do something like that but as long as you can maintain the required 1-1/4" for the cables from the face of the studs, the required conductor length in the box and the box fill I see no problem.

-Hal
Posted By: DougW Re: Residental homerun - 09/16/04 12:55 AM
My old shop used to used deep 1900's instead for all the HR's, with 3/4" (EMT) to the panel.
Posted By: Edward Re: Residental homerun - 09/16/04 01:37 AM
What is a 1900 box. I see you guys mention it all the time.

Edward
Posted By: cpalm1 Re: Residental homerun - 09/16/04 02:21 AM
a 1900 box is the most common type of electrical box. you can fit 2 switches or outlets in it.
Posted By: Attic Rat Re: Residental homerun - 09/16/04 03:20 AM
Quote
What is a 1900 box. I see you guys mention it all the time..
... Edward, a "1900" box gets it's name from a Raco manufactured 4"X4"X 1-1/2" metal box..their item/model # is 190,...hence the term "1900"...
Russ

[This message has been edited by Attic Rat (edited 09-15-2004).]
Posted By: Dave55 Re: Residental homerun - 09/16/04 03:27 AM
I thought the 1900 was in reference to 19.00 cubic inches, but it's actually more than that.

Dave
Posted By: Edward Re: Residental homerun - 09/16/04 03:52 AM
In other words it is a shallow 4S box.
Right?
Posted By: Edward Re: Residental homerun - 09/16/04 03:55 AM
Bot540,
why not use a 5s deep box?

Edward
Posted By: CJS Re: Residental homerun - 09/19/04 11:47 PM
The topic is "residential" homeruns: Why would anyone want to use a metal box in residential? It seems like a BIG waste of money to me...
Posted By: Dave55 Re: Residental homerun - 09/19/04 11:57 PM
As DougW stated, I use deep 4X4s with 3/4" EMT for home runs. I don't get the BIG waste of money. They're 72 cents each.

Dave
Posted By: bot540 Re: Residental homerun - 09/20/04 12:51 AM
Around Chicago you have to use emt and metal boxes for residental.
Posted By: CJS Re: Residental homerun - 09/20/04 05:06 AM
Yeah but it takes alot longer to rough a house in with pipe than with romex AND plastic is alot cheaper too. I don't think I have ever seen a house roughed in with emt. Why would you (unless it is some local ordinance or something like someone said).

It's not as if you can (legally, by code) pull more than 3 current carrying conductors in a pipe; so what benefit is there to piping it in? None that I can see (unless it's required for some strange reason in your area). If I have more than 3 current carrying conductors in that pipe, my 12's become 14's and my 14's become 16's after you derate. You'd have to pull #10's (THHN). It's a waste of time and material --- MONEY!
Unless, like I said, you have no choice.
Posted By: iwire Re: Residental homerun - 09/20/04 09:05 AM
You can put 9 THHN, 14 or 12 AWG current carrying conductors in a raceway before derating becomes an issue.

310.16 shows 14 AWG THHN rated 25 amps

Table 310.15(B)(2)(a) shows a 70% downward adjustment for 7 to 9 current carrying conductors

25 amps x .7 = 17.5 amps

The 14 AWG is still OK for a 15 amp breaker.

For 12 AWG

310.16 shows 12 AWG THHN rated 30 amps

30 amps x .7 = 21 amps.

The 12 AWG is still OK for a 20 amp breaker.

There are areas that must use EMT for residential.

For derating purposes you can use the 90 C column of 310.16 if you use THHN.
Posted By: Fred Re: Residental homerun - 09/20/04 11:41 AM
It isn't required by local code, but I routinely run home runs in my custom homes in EMT to the attic and basement/crawl. I terminate in 12x12x6 pull boxes and run an empty conduit for future expansion. The branch circuits are in RX with the HR stubbed to the crawl/basement/attic for connection in a pullbox.
Posted By: earlydean Re: Residental homerun - 09/20/04 11:48 AM
You can do the same for NM. Article 334.112 requires 90 degree wire and 334.80 allows the 90 degree part of table 310.16 to be used for derating purposes.
This works for 4 NM cables pulled into bored holes also.
Posted By: CJS Re: Residental homerun - 09/20/04 01:04 PM
You cannot pull 9 #12's in a conduit without derating! I certainly never would and I couldn't get away with it around here either!

The only time I recall EVER putting more than 3 current carrying wires in a single conduit (usually you do not have to count your neutral) was at a bank, but it wasn't a homerun. It had a a bunch of switch-legs for "open" & "closed" signs in it and some travellers and I think the feed. In this case you can load it up because half of the wires will always be non-current carrying.

I gotta go make some $$$.

Again: the NEC is a MINIMUM standard. I NEVER run multi-wire BC's; every hot gets itself a neutral, whether it is in pipe or not. Of course, the service also gets a full sized neutral and I balance the perceived loads. It's amazing how many problems this solves.
But, I'll get back to you on this issue later. Gotsta run.
Posted By: CJS Re: Residental homerun - 09/20/04 01:06 PM
And if you really want to use pipe then why not PVC?

Later...
Posted By: mustangelectric Re: Residental homerun - 09/20/04 02:51 PM
Hi,
If you have two double pole GFI breakers one 20A and one 30A going to a single enclosure would you run one or two pipes?

-regards

mustang
Posted By: resqcapt19 Re: Residental homerun - 09/20/04 02:54 PM
CJS,
Quote
You cannot pull 9 #12's in a conduit without derating! I certainly never would and I couldn't get away with it around here either!
Correct, but the derating doesn't change anything. Table 310.16(B)(2)(a) requires a 70% adjustment factor for 7 to 9 current carrying conductors in a raceway or cable. The ampacity of #14 THHN is 25 amps and #12 is 30 amps. The adjusted ampacities for these conductors with 9 current carrying conductors in a race way is 17.5 amps for the #14 and 21 amps for the #12. The maximum permitted overcurrent protection per 240.4(D) is 15 amps for the #14 and 20 amps for #12, so for all practical purposes, there is no derating under these conditions.
As far as using conduit, I see no real advantage of PVC over NM, but I believe that the use of EMT is a safety improvement over both PVC and NM.
Don
Posted By: Fred Re: Residental homerun - 09/20/04 04:49 PM
CJS, I don't think you fully understand derating and you're not alone. I have had this same discussion with several inspectors. You derate from the 90deg column. Take a closer look at the ampacity tables and you will see what IWIRE and Don are talking about. I agree with Don, EMT over PVC. PVC needs to be supported at closer intervals to avoid a sloppy saggy install. I always pull an EGC in my EMT and bond it in every j-box. I install a 14 lug ground bar in the pull boxes to avoid a rat's nest of grounds/wirenuts. MW branch circuits installed in this manner present no more of a hazzard than any other wiring system and in 99% of the circuits they eliminate the neutral as a current carrying conductor for derating purposes.
Posted By: Dave55 Re: Residental homerun - 09/20/04 05:40 PM
I also figure derating the same as the other guys, but I don't run shared neutrals, so I figure 4 circuits maximum in the conduit (counting the neutral as a current carrying conductor).

Why do you pull a ground wire in EMT, Fred?

Dave
Posted By: GETELECTRIC Re: Residental homerun - 09/20/04 07:25 PM
Can you use pvc in the States as we can,t use it in houses up here in Canada and generally our rules are similiar.
Posted By: CTwireman Re: Residental homerun - 09/20/04 08:38 PM
CJS,

Quote
I NEVER run multi-wire BC's;

Why not?

I can think of many excellent reasons for using multiwire circuits:

1. Less labor.
2. 50% reduction in voltage drop.
3. 1 cable instead of 2.
4. 3 wires instead of 4 (assuming pipe).
5. Money saved as a result of 1, 2, 3 and 4
6. Less natural resources consumed

There are even more savings on 3-phase systems.

So why are they so bad?

Peter

[edited for typos]


[This message has been edited by CTwireman (edited 09-20-2004).]
Posted By: Fred Re: Residental homerun - 09/20/04 10:25 PM
Dave55, I pull an EGC in pipe every since I saw a hot wire loose in a j-box arcing around and NOT opening up the CB. It was a brand new school addition and the run of pipe was up through 30' of concrete block. Loose couplings or connectors, it only takes one, and your ground path is gone. I don't understand the aversion to MW branch circuits. I mark the neutrals in the panel to identify which 2 hot wires share them and I mark them in the pull boxes. I don't get why some electricians react to MW branch circuits like they would a live snake.
Posted By: Dave55 Re: Residental homerun - 09/21/04 01:24 AM
Thanks for the reply, Fred. I saw a loose connector with conduit hanging in the air in an attic once which also lost the ground.

I have no aversion to multi-wire circuits when properly installed and maintained by electricians. However, I've seen cases of homeowners and handymen moving the breakers around creating the possibility of an overloaded neutral. I personally don't feel the savings of 50 feet of 12 ga. wire is worth the risk of a fire down the road.

Dave
Posted By: WireWrestler Re: Residental homerun - 09/21/04 01:37 AM
In answer to the original question, I use them occasionally. We are working on a very large residential remodel, 8,000 sq. ft. We ran the homeruns to the attic, and spread out from there. We usually run a lot of branch circuits so they are not loaded up so much, but we may put a bedroom, a closet lite (covered fixture of course!), and maybe a hall light or two on one homerun. This method keeps the number of conductors in switch boxes to a minimum.
WireWrestler
Posted By: Fred Re: Residental homerun - 09/21/04 02:08 AM
Dave55, I just don't subscribe to the "what if somebody down the road does..". The same guy who would indiscriminately move breakers around will probably replace a 20A with a 30A if his 4 plug-in heaters he's using to cure paint in his homemade autoshop paint booth keep tripping the 20A. I never ever fill a panel on a new install. My rule of thumb is to leave at least 8 spaces open in a 40 ct panel even if I have to set a 20 ct sub right next to it with empty pipes up and down out of it. I look at it from the viewpoint of "what if the next competent electrician needs to add a circuit and what if he's me?" If it's me I want it to be easy. If it's not me I want him/her to say "The original electrician was a saint!".
Posted By: Scott35 Re: Residental homerun - 09/21/04 05:18 AM
We should have a semi-detailed discussion thread regarding Derating and etc. per as many factors which may apply (ambient temperature, number of current carrying conductors per raceway, increased size of conductors for adjustments to various factors, which to count and when, yadda-yadda-yadda).

This information is quite easy to understand, yet is not well understood by some Persons in the Field.

Box fill is another issue to address.

These items are simple things to grasp, but if explained by me... well ... might be more difficult!
[Linked Image]

Scott35

BTW, if this post doesn't make too much sense (i.e. missing some key info.), I am "Rubber-Necking" between the Monitor / Keyboard, and the Angels / Seattle game!
Score as of the bottom of the 8th:
Ana: 4, Sea: 2

Also, there's some dude that has become increasingly more buzzed per inning!
Along with the increased intoxication, is an increased dB voice level; and a correspondingly decrease in proper English Speaking skills (Read: Slurred Gibberish is increasing exponentially!)
[Linked Image]

S.E.T.

p.s. Wanted to add the redundant EGC - as mentioned by Fred (adds a Grounding Conductor to EMT runs) is a very good idea, to assure the Electrical Bonding of Metallic Raceways + Equipment.

Me...

[This message has been edited by Scott35 (edited 09-21-2004).]
Posted By: PCBelarge Re: Residental homerun - 09/21/04 10:30 AM
Scott
Got to love them Yanks!!!! [Linked Image]
Sorry Bob.

Pierre

P.S. Oh ya ..., I agree that a good thread on conduit fill and ampacity adjustment would be a good idea, with box fill being separate, and then sizing of larger boxes next.
Posted By: Dave55 Re: Residental homerun - 09/21/04 10:08 PM
Fred, my reasoning for not using shared neutrals is that a thoughtful weekend warrior (even one with some electrical experience) won't overfuse, but may move breakers around without understanding that it's causing a fire hazard. Of course, a fool with a screwdriver can kill himself or burn his house down.

Do you really try to sell a sub-panel on a one circuit job when there are four to eight available spaces in the distribution panel??? I think that would be a tough sell. I'd have a hard time keeping a straight face telling the homeowner they needed it.

Dave

[This message has been edited by Dave55 (edited 09-21-2004).]
Posted By: Fred Re: Residental homerun - 09/21/04 11:58 PM
Dave55, No, I wouldn't try to sell a sub on a 1 circuit job. I rarely do a 1 circuit job but when I do, I sure appreciate it when the original sparky planned for that eventuality. I was talking about new construction in my post. What do you think would prompt a weekend warrior to move breakers around? There would be no reason to move breakers in a 40ct panel as there are no positions available for tandems unless the weekend warrior was going to defeat the tab on the breaker and install a tandem anyway. But then we're back to the fact we all must face: You can make an install idiot resistant but not idiot proof.
Posted By: Dave55 Re: Residental homerun - 09/22/04 12:06 AM
Now I'm with you Fred. I hate going into a fairly new house and finding a 200-amp, 30-space panel full of breakers with no space. I need one circuit and have to add a sub-panel because the original electrician was too cheap to go the extra $50 for a 40-space panel (low-bid work).

Dave
Posted By: NJ Wireman Re: Residental homerun - 09/22/04 04:02 PM
If you were trying to leave a few open spaces for the future, then why not just mini it down later or at that very moment. I find adding a sub for a circuit or so as described above is a joke!! Why upgrade in the first place then.
Posted By: earlydean Re: Residental homerun - 09/22/04 10:02 PM
I have found that a lot of branch circuits are underloaded and that you can usually find two branch circuits to combine into one, thereby gaining a slot for your additional branch circuit. The trick is in determining which two to combine. It may take a lot of research and sleuthing, but it pays off in the long run.
Posted By: Fred Re: Residental homerun - 09/22/04 10:07 PM
NJ Wireman, Nobody was talking about an upgrade. We were discussing new construction. This is just me, but I refuse to install panels made to accept minis. For the extra cost of 6 minis you could have had a 40 ct panel.
Posted By: NJ Wireman Re: Residental homerun - 09/23/04 02:11 AM
Regardless, new or old const. to leave open empty spaces and put in a sub panel is (once again A Joke) and a rip off, wouldn't last to long around here. I did new const for many years from track homes to multi millon $ custom homes and it would have never flew but that is around here if it works for you so be it. But dont be surprised when you get under cut by another ec on the next job due to word of mouth about cost. every home owner somehow knows somebody, who Claims (LOL) to know something about electric. and thats how it all starts.
Posted By: Attic Rat Re: Residental homerun - 09/23/04 02:36 AM
...Wow,..wiring a whole house in EMT,..sounds really tough,..it'd take me 2 years.. [Linked Image] [Linked Image]My GC would definetly fire me!! I can run pipe ok, but I'm not that proficient with it, as I don't do it often enough,..oh well practice makes perfect,(or alot of wasted pipe doglegs)..I guess.. [Linked Image] [Linked Image]
Russ
Posted By: Dave55 Re: Residental homerun - 09/23/04 03:00 AM
After laying a few thousand feet it gets kind of boring, Russ.

Dave
Posted By: Attic Rat Re: Residental homerun - 09/23/04 03:25 AM
... Dave, with that kind of experience you could probably, literally write your name in pipe!! [Linked Image] [Linked Image]
Russ
Posted By: Dallas Re: Residental homerun - 09/23/04 05:41 AM
I've often wondered why so many resi EC's (around me at least) use 30 circuit loadcenters with stabs allowing twin breakers, then use the twins to fill the last 10 spaces to get all their circuits in. The loadcenter isn't that much cheaper than a 40 circuit, and the use of twins run their cost over what a 40 with standard breakers would be. One day I'll get brave and ask one of them at the supply house why. I mean really, just how cheap and bottom line can we get?

We also often trace under-used circuits down to tie together, so that we have a available space for an added 20 amp circuit. It's either that, or the sub-panel route, which takes finding TWO spaces just to add the breaker feeding the sub.
Posted By: Fred Re: Residental homerun - 09/23/04 11:34 AM
NJWireman, I resent the inference to "ripping off" anyone. I don't worry about getting undercut. I have walked away from more than a few jobs where the customer/GC insisted on gutting the electric down to bare minimum. What I think is the true rip-off is a new installation that leaves no room for the inevitable expansion without spending 100s of dollars to add a couple of new circuits when $25.00 extra spent on a full-sized panel or another $50.00 on a sub at the time of construction would have cut the customer miles of slack. If another $25-50 on a $7000 job is going to make/break the EC he's not long for the business. And you're right about one thing in your post, word gets around. I haven't advertised for years and I turn down more work than I take on because there's only so many hours in a day. I've watched dozens of ECs who did whatever it took to cut the price to get a job come and go around here in the last 25 years.
Posted By: NJ Wireman Re: Residental homerun - 09/23/04 01:58 PM
Ok, i will have to agree after waking up this morning and having some time to think about it further, i will say i take back what i said about ripping it off and your last post puts it more in perspective. I just dont know if the ec i work for would allow us to do it. It must be a hard sell? BUT i do totally agree with always being ready for the future, hell i have done jobs where i pulled two spare circuits to the attic and boxed them off just for future use. Regardles i apoligze for the term ripping off that was a little harsh. Im sure you do great work for a great price.
Posted By: mustangelectric Re: Residental homerun - 09/23/04 02:06 PM
i thought piggy back breakers were for existing work only?

you can not use piggy backs on new construction where i am from and get a sticker...

i do not even see a reason why on a new home with a 200A serv one would not install the largest panel available (within reason)

i always leave room for expansion..

mustang

[This message has been edited by mustangelectric (edited 09-23-2004).]

[This message has been edited by mustangelectric (edited 09-23-2004).]
Posted By: Dave55 Re: Residental homerun - 09/23/04 02:11 PM
Per Article 90.1(B)...to paraphrase..following the NEC will result in a safe installation, but not necessarily adequate.

I'm all for leaving spaces in new installations. I just did a 200-amp upgrade that I thought was around 25 circuits. I installed a 40-circuit panel rather than a 30-circuit. As it turned out, with splitting up some circuits and adding some I ended up around 30 circuits.

In the "to each their own" category, I rarely research circuits to find space (unless I've wired the circuits with my usual over-kill), or use half-sized breakers in a full panel. In my opinion, it's time for a sub-panel or service upgrade.

For every customer who can't or won't go for the expense there are three that appreciate it being done right. Researching and half breakers only delay the problem of an inadequate service, and often these services are 100-amp that should be upgraded to 200-amp.

In this area, many of these 100-amp services have an ancient, worn, cloth-covered service entrance cable barely hanging on the house (thanks to the siders). Researching, mini-breakers and sub-panels aren't my idea of a good solution.

Dave
Posted By: earlydean Re: Residental homerun - 09/23/04 05:11 PM
I disagree about upgrading to 200 amps without doing any load analysis. I have found that in most all cases, the electric service is underloaded not overloaded. It has become a point of macho pride to some homeowners about the size of their electric service; "mine is bigger than yours" has grown to include the electric panel too.
It is true that some homes have old, worn out services, and it is true that it does not cost all that much more to install a 200 amp panel and riser. But, if the service and panel are still in good shape, I feel that a load analysis is good sense.
Posted By: tonyc Re: Residental homerun - 09/30/04 04:31 PM
Let me get this right, in Chicago land residential wood frame new construction requires EMT throughout?

I'd have to see it to believe it, my eyes would be as big as saucers.

1/2" stick of emt about $2-$3 a stick
Posted By: bot540 Re: Residental homerun - 09/30/04 09:08 PM
Yes, houses have to be piped in Chicago.
Posted By: DougW Re: Residental homerun - 10/01/04 03:28 PM
My house was built to Chicago code in the 30's.

The whole thing (well, 95%+) is piped in rigid. Makes you have a lot of respect for our ancestors in the EC biz... back in the day when bit and brace, linen covered rubber wires, and soldered splices were the norm.

(no offense, but give me EMT, THHN, and Milwaukee power tools!)
Posted By: KennyFrank Re: Residental homerun - 10/01/04 07:24 PM
Chicago and most of the surrounding counties require conduit, EMT for interior, GRC or IMC for exterior, PVC allowed sometimes for underground. New residential all conduit, no MC cable or BX or NM cable. Smurf tube not allowed either in most areas. You gentlemen from other planets (cuz Chicago can be so weird it is almost a separate planet) would be amazed at how fast an experienced crew can rough a wood frame house - I believe our res guy said a typical 3 bedroom 2 story gets roughed in about 24-30 man hours... 3 guys usually a day or so.
Doug, my mom's house was built in the 1920's, we still have the original blueprints... was a big help when I did my first 'side job' rewiring the whole house. Got bit hard by my first 'Chicago 3-way'
Posted By: Active 1 Re: Residental homerun - 10/02/04 04:26 AM
I could do my name in cursave EMT. Being at $3 a stick I don't want to waist it now. We average a foot of pipe for every SF of custom house. Thats with tall cielings and too many tings in your way for an easy run. If you can't do about 300' a day in the upstairs including drilling and hanging lights and boxes than your not pulling your weight. A great piper will do about 450' a day. Thats with better than average quality.

Some shops go low quality and much more pipe. You wont find 1 made offset in one of those houses. Nothing is pariell or strait. They will conect 1 side of the stick, nail it down, then start bending the other end where it needs to go by hand.

Homeruns we NEVER put it in an unfinished attic. If you can make it in 360 a walk in closet light works well. I like it when the HR pipe points down from the cieling. It nicer to pull. Otherwise an outlet. We try to use 1900 extensions. If it makes the job easier (putting the wires in the box) then the $0.75 extension is worth it. If a worker costing $30 an hour that is $0.50 a minuite. Plus your guy is not frustrated from trying to cram all the wires in the box. We also try to use deeper boxes for switches so you can put in dimmers latter with less struggle.

Tom


Tom
Posted By: George Re: Residental homerun - 10/02/04 06:16 AM
I tend to take a different design direction.

I figure a 20amp 12g circuit is limited to about 75', breaker to last device, by voltage drop considerations. That is not much more than around a good sized room.

I put in lots of 50amp subpanels. Most manufacturers have nice panels that holds 8 half sized breakers. They are small enough to be covered by a picture or mirror. 8 breakers are enough for 600-800 sqft.

My main only feeds the subpanels and 220v loads. No need for it to be large.
Posted By: Dave55 Re: Residental homerun - 10/02/04 03:12 PM
Tom states the trade well for the Chicagoland area. There is so much new home construction going on that the builders electrician moves from one house to the next, often with the same floor plan. After a few of them it gets like factory work and they crank it out. Unfortunately, like factory work, the work is rated and you better make rate.

I'm doing commercial condominiums that are getting fairly routine after two services (4 X 200-amp 3PH) and ten units. Like factory work, you tend to look for new tools, or new methods that will save you a little time.

In this area many of the homes are duplexes, and if the community doesn't require EMT for single family dwellings, they will require it for duplexes.

Dave
Posted By: resqcapt19 Re: Residental homerun - 10/02/04 03:21 PM
George,
[qoute]They are small enough to be covered by a picture or mirror.[/quote]
What about 110.26?
Don
Posted By: tonyc Re: Residental homerun - 10/06/04 10:52 AM
I did some work in Joliet I am from Va. if I had known that the conduit is the norm in residential I would have loved to seen these artists in action I am just blown away by this.
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