Adding sub-panel for basement guidance.

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  #1  
Old 08-02-16, 10:55 PM
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Adding sub-panel for basement guidance.

Hi Folks,
So, we're looking at finishing our basement. We've pulled a permit, completed the framing and now we're looking at doing wiring. I've installed switches, outlets and breakers before. I am currently in the planning/sizing stage and want to make sure I do it right so as to avoid overloading anything.

Here's what we have.

Have 200 AMP main feed.
House is 4200sq/ft(roughly 2100sq/ft up, 2100sq/ft down.)

We currently have one 42-slot breaker distributing power to upstairs, garage, etc. Downstairs we only have 2 15-amp circuits (lights/1 outlet)

We have 10 slots left empty in our panel. What I want to do is:
1. Figure out our current load usage of our 200amp service
2. add a sub-panel (sized appropriately) to feed our basement circuits.

For our basement, we're looking at sizing the subpanel to support a theater room, main/rec room, kitchen, bathroom, 3 bedrooms.

What we're interested in knowing is if we'll have the headroom to do all of these circuits with how our current main breaker panel is situated.

Whats the best way figure out our current load and calculate the amperage / feeder wire size for subpanel?

Here's what our current panel looks like with our current main appliances:
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Can anyone provide any guidance on how we a) calculate our current amp load b) calculate the size of breakers we'd need for sub panel.

Thanks in advance!
 
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  #2  
Old 08-03-16, 11:49 AM
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You can do a load calculation (google it, there are calculators that are much better than I am with it)... but I don't think it's necessary. You're not adding any new significant loads unless you're looking at a new AC zone or electric heat. Lights, receptacles, and a home theater won't cause more than a blip on your overall load.

You can either use those remaining slots for your new circuits or install a subpanel in the basement. It really depends on 1) how many circuits you'll need, and 2) how far will the runs be.

I would probably vote for a subpanel. You'll need/want the following circuits
1) theater (15A)
2) Kitchen countertop receptacles (20A) GFI
3) Kitchen countertop receptacles (20A) GFI
4) Bedroom receptacles 15A or 20A (AFCI)
5) Lights 15A AFCI
6) Bathroom 20A GFI
7) Rec room receptacles 15A or 20A

A 60A subpanel will be more than sufficient for what you need. Plus, that will leave you with 8 open slots upstairs for future use, as opposed to only 3.
 
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Old 08-03-16, 12:07 PM
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Thanks for your help, Zorfdt.

I was hoping that I would have enough headroom for everything we intend to install. Its funny, because 60A for subpanel has been a number floating in my mind.
We're looking at a full kitchen in basement (range/oven and full fridge). Would you think that could change anything? 60A should still be OK? When i convert 11KW to amps (range/oven), i get 50A - does that seem right? Maybe 80A for subpanel might be better, or too much and stick with 60A?
Thanks again!
 
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Old 08-03-16, 12:54 PM
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A 60 amp subpanel refers to the the supplying breaker not the panel. Most times you would use at least a 100 amp breaker panel in order to have enough slots.
We're looking at a full kitchen in basement (range/oven and full fridge)
I'm guessing you have no easy access to gas and want electric for the stove. If you came off the subpanel then I'd say go ahead and do a 100 amp feed. There is option B though run a separate cable from the main panel for the stove. Everything else would probably be okay on a subpanel fed with 60 amps. (Personally I'd go with a gas stove. Most areas it costs less to operate.)
 

Last edited by ray2047; 08-03-16 at 03:58 PM.
  #5  
Old 08-03-16, 02:43 PM
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11 kw is a HUGE kitchen range. Many entire homes in the past, even with electric kitchen ranges and domestic water heaters had only a 60 ampere service.
 
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Old 08-04-16, 11:59 AM
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Thanks Ray2047
I'm guessing you have no easy access to gas and want electric for the stove.
I guess i never considered running gas for a range. I know i can run wires and connect outlets myself and feel pretty comfortable in my abilities there. I do have relatively easy access to gas lines that could be run to the range location (30-40 ft), however i am not confident with my ability to run gas (and i'm total DIY guy) and feel I would need to hire this out. Maybe i'll get some bids and consider as an option. Else, i might wire range outlet to main panel and save room in sub for rest.
or maybe im just chicken and tapping/running gas line isnt as concerning as i make it out to be. In fact, im positive i could tap and run a gas line, its any potential leaks that would have me concerned in a run that long.

Thanks Furd,
11 kw is a HUGE kitchen range. Many entire homes in the past, even with electric kitchen ranges and domestic water heaters had only a 60 ampere service.
Maybe i misinterpreted my freestanding oven/range ratings? When i look at the tag i see two ratings:
120/240v - 11KW
120/208v - 8.3KW

Seems like I'm 240 since i have dual-breaker for the feed to range and that would correspond to the 11KW, correct? Maybe 11KW is the total max draw with ALL burners and oven cranked to highest temperatures?
What doesn't make sense to me is if 11KW converts to 50A, wonder why the 240 breaker in panel for range is 40A.
 
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Old 08-04-16, 01:04 PM
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maybe im just chicken and tapping/running gas line isnt as concerning as i make it out to be.
No not chicken. It isn't just leaks. The total cubic feet used by the range must be considered and the math done to see if the nearest source can supply the amount of gas needed. Often a new line needs to be run from the meter.
Seems like I'm 240 since i have dual-breaker for the feed to range and that would correspond to the 11KW, correct?
Both 120/208 and 120/240 use double breaker. 120/240 is a single phase voltage found in most homes. 120/208 is a 3 phase derived voltage found in mostly commercial buildings and some large multi family buildings. As Jeff Foxworthy might say if your house is three stories are more and has an elevator you might have 120/208.
 
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Old 08-04-16, 01:06 PM
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Your range uses both 120 AND 240 volts. The reference to 208 volts is mostly for certain apartments that are in big buildings and have a three-phase service; these will have 120 and 208 volts.

A "normal" (whatever normal is) kitchen range would be rated around 8.5 kW or so. This rating includes EVERYTHING on the range, all top burners running on high, the broiler going full tilt and the warming drawer (if it has one) in use. Since it is almost never that a range will be used to that extent the code allows a "fudge factor" to be used that lowers the requirements of the circuit.
 

Last edited by ray2047; 08-04-16 at 01:18 PM. Reason: bug>big
  #9  
Old 08-06-16, 01:40 PM
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Thanks everyone for your guidance. I have a much better idea on how I want to proceed.
Thanks again!.
 
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Old 08-19-16, 11:58 PM
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I've opted to run breaker for kitchen range in main panel.
I have a 42 space Eaton/Cutler Hammer CH main panel.
I just purchased a 60AMP dual-pole breaker and 45ft 4/3 NM-B to feed my new 12 space Eaton BR sub-panel. (Any issues running CH and BR together?)

I have a couple of obstacles and questions i was hoping you could help me with:

First, my understanding with 2014 NEC is practically any room needs to be AFCI.
I purchased a 3 15A AFCI "Combo" breakers to start with (jeeze, these arent cheap).
By AFCI "Combo", does combo indicate its AFCI AND GFCI or is there some other feature that makes it a combo?

Second, I need a little guidance on how I can run the 4/3 feeder from main panel to sub-panel. I did rough measurement of distance from main to sub before i hit hardware store to have a bulk chunk of wire cut for me. When i got back, i then realized some obstacles were in the way in the form of fresh air ducting in the joists and heat/cool ducting.

Since i have a permit pulled for this work, and anticipate inspection at some point, im making an effort to do everything as clean and adhered to code as possible.

I took some pictures of the main panel, and the route i plan to take with the 4/3 feeder.
Immediately departing the panel in a vertical run I have the option to go through the joists (preferred) but i would have to go perpendicular through joists that are set as fresh air ducting(red line. I've not found any confirmation on whether this was actually allowed by code or not. I've found others interpretations on it, but nothing concrete.

Red dotted line would be through joist/fresh air return.
Orange dotted, would be running 4/3 in between fresh air and heat ducting.
(either allowed??)
Attachment 69867

Here is the path immediately after the fresh air duct. I was thinking if NOT going through joists that double as fresh air return, I would anchor to gas line that would run parallel (orange line).. Is this allowed?
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Here is another shot suggesting continuing 4/3 NM-B down anchored to gas line (allowed?):
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Finally, here is the 4/3 NM-B feeder run (anchored to gas line) running to new imaginary sub panel:
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Any thoughts on which might be best, allowed by code, or i need a new plan...
Thanks!
 
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Old 08-20-16, 03:34 AM
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Combination AFCI circuit breakers include GFCI protection.

Running type NM cable through a return air duct perpendicularly is frowned upon but it is acceptable in the NEC. Your LOCAL code may have closed this loophole and prohibit such a practice. Running cable through a supply duct is not allowed as far as I know. You could "sleeve" a piece of conduit through the duct perpendicularly and seal the ends to the joists and this should be okay under your local code but before doing it get your inspectors okay.

The cable must be anchored independent of any other utilities so no, you cannot use the gas piping for support.
 
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Old 08-20-16, 10:01 AM
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Furd,
Thank you for your help in clarifying AFCI combo breaker and do's/dont's of my wire run situation.

I am thinking i will run between the bottom of the joist/fresh air return and a heat duct that sits below (approx 2 in space). my only concern is that it could be too close to heat duct. I may have to identify another route. I'll keep thinking about this.

I have another question.
I cracked open my new sub-panel (pic below) and I have the understanding that I should do the two following things:
1. Remove bonding strap between neutral and ground bus bars.
2. Have ground bus bond to case.

OR

Leave bonding strap between two busses and buy/install dedicated ground bus?

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Thanks!
 
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Old 08-22-16, 11:23 AM
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Combination AFCI circuit breakers include GFCI protection.
No, they don't. A combination arc fault breaker is just the latest version of arc fault protection which protects against both parallel and series arcing faults. The earlier version arc faults only protected against parallel arcing faults. If you want both AFCI and GFCI protection in a single circuit breaker you need to get a "Dual Function" AFCI/GFCI circuit breaker. I know both Eaton/Cutler-Hammer and Square D make them and assume Siemens does too. Not sure about GE.


Leave bonding strap between two busses and buy/install dedicated ground bus?
Those are both for neutrals. Do not install the bonding strap, throw it away. Notice that they are both mounted on insulating feet to keep them isolated from the panel box. Purchase a separate ground bar kit for the panel, it will mount right on the metal box to pre-punched holes and is automatically bonded to the panel box. Terminate all neutral conductors on the neutral bus, either one is fine. Terminate all grounding conductors on the new auxilliary ground bar you are installing.
 
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Old 08-23-16, 01:33 PM
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No, they don't. A combination arc fault breaker is just the latest version of arc fault protection.....
Thanks for your help in clarifying this for me, CasualJoe. Also, thanks for the input on my panel. I pulled ground bonding piece and threw across basement and added new ground bus.
I have panel mounted and ready for my 4/3 feeder.

Now, a question I have on running my feeder. I initially intended to run this cable between (perpendicular) to fresh air return (above) and cold/heat duct (below). There is approx 1 3/8" gap. The reason I chose this to begin with is there is already a pex and other low-voltage wire running through this same passage, but i have recently thought of some concerns with this route.
first - Heat. Since this heat/cool duct (bottom) virtually immediately exits the furnace, i would suspect it to get relatively hot. I don't know how hot as i've not measured, and it is summer time. My concern is this could, over time, compromise the shielding on this 4/3 NM-B. Additionally, heat should be calculated when planning as this affects the current, doesn't it?

Here are some pics of what I planned to do. I already bought the cable with this plan in mind ($160 for 45ft). I'm hoping i can go this route:
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If i can't/shouldnt run this feeder through this area, could I use any sort of conduit or insulation that might allow me to feed through this spot?

Thanks in advance!!!
 
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Old 08-23-16, 03:25 PM
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I would not worry about the temperatures the cable will see. It is well below the insulation rating.
 
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Old 08-23-16, 03:57 PM
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I would not worry about the temperatures the cable will see. It is well below the insulation rating.
Thanks pcboss. That helps ease concerns. Now, regarding any codes (IRC/IBC/IFC/IMC/IDC/NEC), could this be a violation of any? Such as min distance away from ducting, etc? Thanks!
 
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Old 08-23-16, 04:57 PM
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None that I am aware of. .
 
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Old 10-24-16, 10:05 AM
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Just wanted to say thanks to everyone for their help on this.

I have my feeder run to panel and all my branch circuits are run. other than some bathroom plumbing, drain & tub work, i'm very close to my inspection.
Thanks again!
 
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