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electrical wiring question
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MYoung



Joined: 24 Feb 2007
Posts: 369
Location: Madison, WI


PostLink    Posted: Wed Sep 17, 2008 3:24 am    Post subject: electrical wiring question Reply with quote


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I'm wiring a room in my basement for running a CRT projector (likely a 1271Q or D50), an entry-level Sony 5.1 surround sound system (it states 900W, though I take it it's a marketing gimmick), and a PS3 and/or HTPC. The single circuit which I'm hoping will run all of that equipment is 15 amps. Nothing else will be on this circuit -- lights are on a different circuit. Being new to electrical wiring, I wasn't sure what gauge of wire to use. I did some "research" online and found someone mentioning that 14 gauge can be used with 15 amp circuits. I already started doing some wiring with 14 gauge but I'm now wondering if I should remove that and switch to 12 gauge wire now that I've read others saying that 14 gauge is okay for lighting, but not for more power hungry devices. In addition, after already buying the wire I see that the wire I'm attaching to (there's already wire leading to the breaker box for this circuit as it was a circuit I disabled to rip out some nasty floor, wall, and ceiling wood in this particular room) and that wire appears to be 12 gauge. I thought it was 14 gauge, though I should have checked for sure. Anyway, figured I'd ask if I should proceed with the 14 gauge or switch to 12 gauge before I go any further only to redo my work. Thanks!
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Curt Palme
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PostLink    Posted: Wed Sep 17, 2008 3:30 am    Post subject: Reply with quote

12 gauge is good for 20 amps. If you think you'll put in a kickass system down the road, then by all means, use 12. It's a bit stiffer wire and a bit harder to work with, shouldn't be too much more expensive.
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MYoung



Joined: 24 Feb 2007
Posts: 369
Location: Madison, WI


PostLink    Posted: Wed Sep 17, 2008 3:32 am    Post subject: Reply with quote

Hmm, after taking a closer look at the pre-existing wire that leads back to the circuit breaker, it actually is 14 gauge, not 12 gauge. So if I switch to 12 gauge I'd need to replace that while wire back to the box. I'm guessing now that I'm okay with the 14 gauge, though if someone who knows a thing or two about wiring could verify that I'd appreciate it!
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Curt Palme
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PostLink    Posted: Wed Sep 17, 2008 3:38 am    Post subject: Reply with quote

Yup, switching to 12 gauge midstream won't do anything for you.
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AnalogRocks
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Joined: 08 Mar 2006
Posts: 25396
Location: Toronto, Ontario, Canada

TV/Projector: Sony 1252Q, AMPRO 4000G


PostLink    Posted: Wed Sep 17, 2008 4:22 am    Post subject: Reply with quote

Curt Palme wrote:
Yup, switching to 12 gauge midstream won't do anything for you.


15 amp AC circuits are 14 gage and
20 amp circuits are 12 gage.

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MYoung



Joined: 24 Feb 2007
Posts: 369
Location: Madison, WI


PostLink    Posted: Wed Sep 17, 2008 5:12 am    Post subject: Reply with quote

Thanks for the clarification guys!
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jkruger



Joined: 24 Oct 2007
Posts: 2435
Location: Carlsbad, CA


PostLink    Posted: Wed Sep 17, 2008 6:03 am    Post subject: Reply with quote

12 gage versus 14 gage might run a litle more now, but in 5 yrs it will cost a lot more. Do it now, and you will be glad you did.
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AnalogRocks
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PostLink    Posted: Wed Sep 17, 2008 7:14 am    Post subject: Reply with quote

jkruger wrote:
12 gage versus 14 gage might run a litle more now, but in 5 yrs it will cost a lot more. Do it now, and you will be glad you did.


I'd agree with this. If you need to up the ante to 20 amp it's much easier to wire for 12 gage now then to rewire later.

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ecrabb
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PostLink    Posted: Wed Sep 17, 2008 8:49 pm    Post subject: Reply with quote

Or, if you have the spaces in the panel for it, just add another circuit. It's probably less work than tearing out completed/installed work, and there's no waste of materials. Unless you can't split stuff up, two 15A circuits gives more capacity and flexibility than one 20A circuit, too.

I went totally overboard and ran a 20A circuit to the projector AND a 20A circuit to the rack. Then I ran a 15A circuit to room outlets (including the subs), and a 15A circuit to the room lighting. I think I have a fifth circuit, too but I can't remember what for right now.

SC
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WanMan



Joined: 19 Mar 2006
Posts: 10261



PostLink    Posted: Thu Sep 18, 2008 12:35 pm    Post subject: Reply with quote

Overboard? Look at this ...


Basement Electrical Requirements.doc
 Description:

Download
 Filename:  Basement Electrical Requirements.doc
 Filesize:  31 KB
 Downloaded:  271 Time(s)


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emdawgz1



Joined: 14 Mar 2006
Posts: 7949



PostLink    Posted: Thu Sep 18, 2008 12:47 pm    Post subject: Reply with quote

Think about what goes into a typical theater room.

Crt pj
Video processor
Audio receiver
Amps
Computer
DVD
PS3
lights
hvac

That one room draws a lot of power. An electric kitchen may draw as much but usually not at the same time.
Sturdy wiring is a must.

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MYoung



Joined: 24 Feb 2007
Posts: 369
Location: Madison, WI


PostLink    Posted: Thu Sep 18, 2008 8:39 pm    Post subject: Reply with quote

This basement home theater of mine will very much be low-end for playing PS3 and perhaps a movie from time to time, so it sounds like a single 15A circuit should do the job. I do have another circuit that was originally running into the other half of the room that I'm eventually hoping to re-establish in that room, though not for home theater use. I suppose if I added more equipment, it would be easier to just tap into that circuit.

Unfortunately, that room has a history of getting a wet floor during heavy rain! That prevents me from finishing it properly. No drywall in its future! Though I think it would be neat to put up some curtain rods spanning across the walls of the room and get some black curtains. I was originally hanging black sheets on all the walls with black carpet and as much black everything else. It sure make a difference in the picture! Of course, about a year later it rained really hard after I tore out my gutter covers because maple seeds clogged them all up. My gutters must have gotten plugged and presto, flooded home theater room! Not cool. Lost all my area rugs and lots of time dismantling everything. Though the flood is giving me a good chance to rebuild my screen frame and properly wire electrical outlets to that room. Even though I had GFCI protection on the outlets I was plugging extension cords into for powering the theater, extension cords on the floor are so ugly.
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jkruger



Joined: 24 Oct 2007
Posts: 2435
Location: Carlsbad, CA


PostLink    Posted: Fri Sep 19, 2008 1:04 am    Post subject: Reply with quote

WanMan wrote:
Overboard? Look at this ...


WTF? How could you possibly expect to run that much stuff on a single 100A panel?
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ecrabb
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Joined: 13 Mar 2006
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Location: Utah

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PostLink    Posted: Fri Sep 19, 2008 4:31 am    Post subject: Reply with quote

John, it's not as bad as you think... Check my numbers in red:
emdawgz1 wrote:
Crt pj (700w)
Video processor (200w)
Audio receiver (1200w)
Amps (3@500w=1500w)
Computer (200w)
DVD (150w)
PS3 (200w)
lights (1000w)
hvac (700w) (maybe)

So, worst case is almost 50A. Four 15A circuits would easily cover it. The amps and the receiver are never drawing their rated current for more than brief instants in time. Real draw would probably be half that 50A most of the time.

emdawgz1 wrote:
That one room draws a lot of power. An electric kitchen may draw as much but usually not at the same time.
Sturdy wiring is a must.

Don't you cook breakfast? We constantly have the oven, a burner or two on the range, the microwave, a toaster and the lights all on at the same time. Don't forget the fridge and dishwasher! Just the oven and a stove burner or two probably draw as much or more than my entire HT. Add in the toaster and microwave, and there's no comparison.

Good wiring in the HT is a great idea, but the kitchen is BY FAR the heavy consumption room in the house if you're not using a gas range.

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jkruger



Joined: 24 Oct 2007
Posts: 2435
Location: Carlsbad, CA


PostLink    Posted: Fri Sep 19, 2008 4:34 am    Post subject: Reply with quote

Did you add up all the stuff on this list?

Wired to a 100A dedicated Sub-panel tied to existing Main panel.
Quote should not include sconces, fans, pendent or under-counter fixtures.

Theater Room (underneath Formal Living & Dining Rooms)
Eight 6 canned lights on 1st wall switch.
Two ceiling electrical boxes for surface lighting on 2nd wall switch.
Four wall sconces electrical boxes on 3rd wall switch.
General electrical outlets on 15A or 20A circuit.
Six wall electrical outlets on dedicated 20A circuit.
One ceiling electrical outlet on dedicated circuit 15A.

Media-Music Room (underneath Kitchen & Breakfast Rooms)
Five 6 canned lights on 1st (3-way) wall switch.
Three 4 canned lights in soffit on 2nd (3-way) wall switch in traffic area.
Three 4 canned lights in soffit on 3rd wall switch at window area.
One ceiling electrical boxes for fan/light on wall switch.
General Electrical outlets on 15A or 20A circuit.
Two wall electrical outlets on dedicated 20A circuit.

Lounge Room (underneath Family Room)
Five 6 canned lights on 1st wall switch.
Three 4 canned lights in soffit on 2nd wall switch.
Three ceiling electrical boxes for pendent lighting on 3rd wall switch.
General Electrical outlets on 15A or 20A circuit.
One ceiling electrical boxes for fan/light on wall switch.

Kitchen (underneath Study)
Four 6 canned lights on 1st wall switch.
Three electrical outlet/boxes on dedicated circuit on 2nd wall switch.
General GFI Electrical outlets on 15A or 20A circuit.
Dedicated Electrical circuits for appliances.

Bathroom
Two 6 canned lights on 1st wall switch.
Two wall sconces electrical boxes on 2nd wall switch.
Ceiling exhaust fan on 3rd wall switch.
General GFI Electrical outlet(s).
One 15A or 20A ejector/sump pump circuit.

Hall & Staircase
Two 6 canned lights in hall & stair landing on 3-way wall switch.
Three or four wall-washer lights on 3-way wall switch.

Utility Rooms
One surface light on wall switch in each room.
One (general) electrical outlet.

Underneath Staircase
One surface light on wall switch.
Two electrical on 15A circuit.
Two electrical outlets on dedicated 20A circuit.
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ecrabb
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Joined: 13 Mar 2006
Posts: 15909
Location: Utah

TV/Projector: JVC RS40, Epson 5010


PostLink    Posted: Fri Sep 19, 2008 4:52 am    Post subject: Reply with quote

I was talking about John's list, not Wan's Word doc.

Still, Wan might be OK, anyway. I counted about 20-odd circuits, but I didn't try to tally total draw. Why do you assume it's not possible? Entire houses used to be on 100A service, and this is just a basement. No range/oven, no A/C, no clothes dryer.

Think about your house's 200A service. There are probably enough 15A and 20A circuits on top of central A/C, dryer, and range to add up to 600 or 700A. I don't remember what the rule is, but if you consider that an entire house (with all the aforementioned heavy draw appliances) can run on 200A service, I don't see a problem with a basement full of lights and outlets and an HT running on a 100A sub panel. My basement is on a 60A sub panel!

SC
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WanMan



Joined: 19 Mar 2006
Posts: 10261



PostLink    Posted: Fri Sep 19, 2008 9:29 am    Post subject: Reply with quote

I do not see my basement consuming more than 100A at any time. The entire house now has 150A. Had the main breaker been something other than Cutler-Hammer, they'd have worked that hot, but unfortunately the CH main breaker is not a plug-style unit, which means they have to touch the meter-side wiring hot.

BTW, as of 3PM yesterday I've hired the electrician. They are bringing in a monkey to install dead-wood for the drywallers, so the drywallers don't accidentally plow through sheetrock and into wiring they're installing. Hopefully a week from tomorrow the basement will br ready for the drywallers to come in.

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tri_joel



Joined: 03 Jul 2007
Posts: 639
Location: Northern Virginia


PostLink    Posted: Fri Sep 19, 2008 2:15 pm    Post subject: Reply with quote

Crt pj (700w) = 5.8 amps
Video processor (200w) = 1.7 amps
Audio receiver (1200w) = 10 amps
Amps (3@500w=1500w) = 12.5 amps
Computer (200w) = 1.6 amps
DVD (150w) = 1.25 amps
PS3 (200w) = 1.7 amps
lights (1000w) = 8.3 amps
hvac (700w) (maybe) = 5.8 amps

Total amp draw assuming all are on and drawing entire rated amps = 48.65 amps

Lights are probably not going to be on and the HVAC cycles.

Actual amp draws are typically about half of the name plate data.

You don't need 20 amp rated outlets, unless you are planning on using a vacuum while 6 400 watt lamps are plugged in and turned on in each of 6 (per code) outlets.

Does an audio reciever really eat up 1200 watts? Seems a bit high to me, but I really don't know.

Food for thought.

Joel
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MYoung



Joined: 24 Feb 2007
Posts: 369
Location: Madison, WI


PostLink    Posted: Fri Sep 19, 2008 10:50 pm    Post subject: Reply with quote

For my living room home theater I used a Kill-A-Watt to measure Amps drawn from my devices while playing a loud DVD (on my admittedly low-end surround sound system) and projecting a white screen on the projector...

1292Q: 6A
HTPC: 1.5A
HD DVD player: 0.7A
VisionHDP: 0.05A
500W 5.1 surround sound receiver: 0.65A

Total: 8.9A
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ecrabb
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Posts: 15909
Location: Utah

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PostLink    Posted: Sat Sep 20, 2008 12:35 am    Post subject: Reply with quote

Joel, you're right - Most AVR's would rarely ever come close to 1200w. I just used the consumption spec for an Onkyo TX-SR875, which is rated for 9.8A. I was just using it as a worst-case scenario. Actual consumption would be FAR less - especially if you're using outboard amps instead of the internal amps. I'm sure typical consumption would more like a couple of amps. Even if it was significantly more, it would be very short in duration... unless you like to listen to white noise at 102dB or something. Wink

Mike, those figures are all exactly what I'd expect. I need to buy a Kill-A-Watt and check some things, too. I've wanted one for a long time, but just never got around to getting one. One of the figures did catch my eye... The 5.1 surround receiver... At .65A, that's only about 78w. 78 watts! Barely more than a 75w light bulb!!! On the INPUT side of the power supply! Assuming even a 90% efficiency (wildly optimistic), that would be about 70w... divided by 5 channels (assuming the sub has its own power supply), that means the amps are probably running about 14wpc... which is probably the unvarnished truth. I'm not making fun or anything - I know we've talked about your system specifically before - it's just amazing to me that these companies can get away with these ridiculous marketing claims.

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