Hi,

I am doing a second addition, all work myself consisting of a new kitchen, rec room and expansion of master bedroom; I feel comfortable with electrical work in general and my previous work passed with flying colors but I would very much appreciate guidance; I will say in advance it's extremely generious of you pro's to offer same!

I am running a sub-panel because my existing Cutler Hammer CH load center is pretty much full but mostly because it's a long way to the new addition (> 100 feet) and I want to minimize voltage drop and I plan a future additional exteriour sub-panel as well. My main panel is well grounded both at main copper feed and with grounding poles.

1. Sub-panel location: I know I should not put near flamables (e.g. a closet) and that I must honor the access area requirements stated in the code but I can't tell what other restrictions apply: can I place the sub-panel in an interior wall for example? Any additional wall-board/fireproofing restrictions?


2. Arc-fault breakers: the code is pretty clear that I should be using them in most rooms but does not mention kitchens, and does not distinguish between lighting and receptical circuits that I can tell so:
Should I use arc-fault in Kitchen? (I already am aware of GFCI requirements.)
How about for a pure lighting cirquit?
Shop recepticals and lighting?


3. Load
3a: Future extension sub-panel:
I have included a future outdoor sub-panel in my load calculations: is there anything wrong with running a seond sub-panel from the first? Does the fact that it will be outside (in a weathproof enclosure and using outdoor cables of course) affect this? The reason I wish to go sub-panel is two fold: 1) Breakers are scarce in my main panel (though I could go half/height I guess) 2) It's a much shorter and easier run.


3b Ampacity:
I calculate 80 amps is more than sufficient for all projected load. I translated this to:
3 #4 THHN conductors running from paired 40 amp breakers. (And I will make an effort to rebalance load on the main panel as well.) A portion of the run is outside so I plan 1" electrical grade PVC which allows 3, or 1 1/4 which allows six if there is benefit.

3c Grounding:
It's my understanding that I do NOT ground a sub-panel and either use a panel specifically designed for same or convert a Cutler Hammer main panel. Amy I correct? Any advice on panel?

Again, thanks so much for taking the time for me!

Sam

I'll take a stab at 3c) Grounding the sub-panel.

You don't bond the neutral to the ground in the subpanel. Neutral is isolated. Ground is ground. L1, L2, N and G run back to the main panel. You may need to purchase a ground lug kit for the sub-panel. The use of a main breaker in the sub-panel is strictly optional. In this case you will end up with 2 means to disconnect.

If the sub-panel is in the same building, it does not need a separate ground rod.

I'm sure TK will recommend that all the sub-panels are fed from the main panel.

(1) Boy... there are a lot of variables that go into that question. But you can put the panel in an interior wall. Whether the wall you have in mind will work depends on other factors as well. For example, the stud cavity is not to be shared with plumbing lines. (again, exceptions) The one I installed in my shop had a drain for the water heater running through the bottom of the cavity. I had to frame around that to pass.

(2) AFCI's are normally required in all new bedrooms. However, each jurisdiction can have it's own requirements depending on what issue of the code they adopt plus and special adopted rules they have added. Call your AHJ on this.

(3) A second sub can be run from the first sub. If the second sub is located outside the main building, you have other regs to comply with.

KISS is right on the money.

There are some very talented folks here who can offer more in depth advice than I. I would wait for them to chime in too.

The answers given so far are good, allow me to add some info, my comments are in bold:


1. Sub-panel location: I know I should not put near flamables (e.g. a closet) and that I must honor the access area requirements stated in the code but I can't tell what other restrictions apply: can I place the sub-panel in an interior wall for example? Any additional wall-board/fireproofing restrictions?

Yes, the panel can be on an interior wall. The only fireproofing materials needed will be according to the construction methods, for example if one side is a garage, that side will need a fire rating of 1 or 2 hour.

The holes drilled in wood framing members for cables above and below the panel will need fire caulk after the cables are installed.

Code calls for no panels in closets or bathrooms. Some states do not allow a panel in a stairwell. Makes sense if you think about it. So check your local code.


2. Arc-fault breakers: the code is pretty clear that I should be using them in most rooms but does not mention kitchens, and does not distinguish between lighting and receptical circuits that I can tell so:
Should I use arc-fault in Kitchen? (I already am aware of GFCI requirements.)
How about for a pure lighting cirquit?
Shop recepticals and lighting?

The new 2008 code calls for AFCI protection in the following areas, family, dining, living, libraries, dens, bedrooms, sunrooms, rec room, closets, hallways, or similar rooms or areas.

Correct, clearly kitchens are not required. You may if desired, but I would leave a kitchen with only GFI protection as required.

When the code states " all circuits" in the areas I listed, that means all circuits. You should check with local codes thou, some states have waivered the AFCI requirement for smoke detectors, and do not allow detectors on AFCI protection.

A shop is not listed for AFCI protection.

Check with your inspector, only the new circuits in the new addition should be subjected to the new code requirements. Also check to see which code edition is in effect in your area.

3. Load
3a: Future extension sub-panel:
I have included a future outdoor sub-panel in my load calculations: is there anything wrong with running a seond sub-panel from the first? Does the fact that it will be outside (in a weathproof enclosure and using outdoor cables of course) affect this? The reason I wish to go sub-panel is two fold: 1) Breakers are scarce in my main panel (though I could go half/height I guess) 2) It's a much shorter and easier run.

While a subpanel can be fed by a subpanel, as long as the load calcs are done to insure one panel can feed it's load plus the downstream subpanel, I do recommend all subs be fed by the Main panel, for obvious reasons.

The outdoor issue is irrelevant to where it is fed from.



3b Ampacity:
I calculate 80 amps is more than sufficient for all projected load. I translated this to:
3 #4 THHN conductors running from paired 40 amp breakers. (And I will make an effort to rebalance load on the main panel as well.) A portion of the run is outside so I plan 1" electrical grade PVC which allows 3, or 1 1/4 which allows six if there is benefit.

Something does not make sense, an 80 amp calculated load fed by 40 amp breaker?

The 3 - #4 copper is fine, need to add a #8 green for an equipment ground in the conduit. All would fit in a 1" Sch 40 PVC conduit.

3c Grounding:
It's my understanding that I do NOT ground a sub-panel and either use a panel specifically designed for same or convert a Cutler Hammer main panel. Amy I correct? Any advice on panel?

Not sure I understand your thinking. Each subpanel needs an equipment ground wire from the source panel. The neutral bar is to be kept insulated and isolated and used only for white neutrals. The equipment ground wire connects to a separate equipment ground bar that is bolted directly to the panel box using machine thread screws, may need to purchase this bar as an accessory.

Cutler Hammer is a fine product, as is Square D, GE, Seimens are other popular products. There are other brands that are regional that I am sure are just as good.

Thanks much to all of you!

And yes, the 40 amp breaker feeding 80 amp panel was a typo, I primarily wanted to reality check my calculation that #4 THHN was sufficient after derating.

I feel much more confident that I can proceed as planned and won't have to yank anything out. Reading code is fine but there is no substitute for experience.

P.S. Special thanks for alerting me to the location of the online code! I bought another book (small but expensive pocket guide) because I could not locate same and thought it was not available.

Now that I've found this site I'll make a point of passing it on by posting in some of my areas of expertise.

Regards,

Sam Atwater