Circuit breaker question- quick - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #1 of 53 Old 07-07-2013, 03:25 PM - Thread Starter
AVS Special Member
 
pdxrealtor's Avatar
 
Join Date: May 2005
Posts: 2,523
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 119 Post(s)
Liked: 143
I have a contractor coming to add two 20 amp breakers. In the past I've read about something being on the same leg.... I can't remember if it is the ground or ???

So... what do I need to make sure the contractor does to prevent the Hum that could possibly happen if breakers are not installed in a certain way?

FS- Netgear 550 .ISO player - PM me
My Gear-Pioneer, JBL Pro Cinema, Fi Car Audio 4- SP4 18", Peavey IPR2 7500 x 4 -Mini-Dsp 4x10, GIK Acoustics, Seymour Screens 110" AT, Dune Smarts, uNraid Server
Theater Build and Two Sono Sub Builds Here-
pdxrealtor is offline  
Sponsored Links
Advertisement
 
post #2 of 53 Old 07-07-2013, 03:58 PM
 
gregzoll's Avatar
 
Join Date: Jun 2009
Posts: 2,524
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 32
Why can't you do the work yourself? Why pay someone for something that is so simple a child can do it. As for the hum, it comes for poor grounding of the electrical system, and ground loops caused by people over grounding stuff like telephone, catv and a/v equipment, not knowing what they are doing, along with no grounds or poor connection between the ground and ground bar or ground system, caused by corrosion, or "bootlegging" off of the Neutral.
gregzoll is offline  
post #3 of 53 Old 07-07-2013, 04:14 PM - Thread Starter
AVS Special Member
 
pdxrealtor's Avatar
 
Join Date: May 2005
Posts: 2,523
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 119 Post(s)
Liked: 143
It had to do with making sure something is on the same leg......

FS- Netgear 550 .ISO player - PM me
My Gear-Pioneer, JBL Pro Cinema, Fi Car Audio 4- SP4 18", Peavey IPR2 7500 x 4 -Mini-Dsp 4x10, GIK Acoustics, Seymour Screens 110" AT, Dune Smarts, uNraid Server
Theater Build and Two Sono Sub Builds Here-
pdxrealtor is offline  
post #4 of 53 Old 07-07-2013, 04:29 PM
 
gregzoll's Avatar
 
Join Date: Jun 2009
Posts: 2,524
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 32
Quote:
Originally Posted by pdxrealtor View Post

It had to do with making sure something is on the same leg......
Incorrect. Does not matter if both breakers are on the same leg if you are using 12/2. What matters is if you are using 12/3 for the two circuits, since both breakers have to be on opposite legs on the panel. Even if you have them on the same leg, using 12/2 you are not going to get hum on the system.

Hum is again caused by poor or incorrect grounding, or poorly maintained electrical systems, not whether breakers are on the same or opposite legs on a panel.
gregzoll is offline  
post #5 of 53 Old 07-07-2013, 04:36 PM - Thread Starter
AVS Special Member
 
pdxrealtor's Avatar
 
Join Date: May 2005
Posts: 2,523
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 119 Post(s)
Liked: 143
We are using a breaker that is two breakers in the size of one. Square D. So we are taking out a current 20 and adding a double breaker, one for current 20 and one for new dedicated 20. 12/2 will be used, no /3 wire will be used.

We will do this x 2 or we could just add both new circuits to the same 'double' circuit breaker and combine both current 20 amps to the same double circuit breaker. Makes no difference for us, only in the end result.

FS- Netgear 550 .ISO player - PM me
My Gear-Pioneer, JBL Pro Cinema, Fi Car Audio 4- SP4 18", Peavey IPR2 7500 x 4 -Mini-Dsp 4x10, GIK Acoustics, Seymour Screens 110" AT, Dune Smarts, uNraid Server
Theater Build and Two Sono Sub Builds Here-
pdxrealtor is offline  
post #6 of 53 Old 07-07-2013, 04:59 PM
 
gregzoll's Avatar
 
Join Date: Jun 2009
Posts: 2,524
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 32
That is called a Dual breaker. Does not matter what company is stamped on it, all dual breakers when placed in a panel use opposite legs. If they didn't, you would only get 120Vac if you tried to use that breaker for a 240Vac circuit.

Now of course if it is a split bus panel, or using Tandem breakers in a split bus, then you can end up with the same leg on the left, and same leg on the right on some of the older panels. All new panels have every other breaker slot is an opposite leg from the next one down.
gregzoll is offline  
post #7 of 53 Old 07-07-2013, 05:04 PM - Thread Starter
AVS Special Member
 
pdxrealtor's Avatar
 
Join Date: May 2005
Posts: 2,523
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 119 Post(s)
Liked: 143
Lol... so in laymen terms what do I tell my contractor to make sure NOT to do when adding two breakers. The goal being to avoid any HUM noise.

FS- Netgear 550 .ISO player - PM me
My Gear-Pioneer, JBL Pro Cinema, Fi Car Audio 4- SP4 18", Peavey IPR2 7500 x 4 -Mini-Dsp 4x10, GIK Acoustics, Seymour Screens 110" AT, Dune Smarts, uNraid Server
Theater Build and Two Sono Sub Builds Here-
pdxrealtor is offline  
post #8 of 53 Old 07-07-2013, 05:09 PM
HOME THEATER CONTRACTOR
 
BIGmouthinDC's Avatar
 
Join Date: Jan 2003
Location: Northern VA
Posts: 21,500
Mentioned: 10 Post(s)
Tagged: 1 Thread(s)
Quoted: 575 Post(s)
Liked: 738
Quote:
Originally Posted by gregzoll View Post

all dual breakers when placed in a panel use opposite legs.


Not a true statement. A double breaker intended to squeze two circuits into to the space of a single breaker are on the single leg of the original breaker and provide two entirely separate circuits.
Now a double wide breaker intended to provide 240 will have two legs. The width of the breaker spans the alternating legs.


a double will look like this

681529_front500.jpg

a two pole breaker for 240 looks like this

A0ZC_129780407745469159fKqoLfENa6.jpg

Of course there are other variants like half height breakers, and I suppose you there are doubles that installed straddling two single slots are on different legs.
auburnu008 likes this.
BIGmouthinDC is online now  
post #9 of 53 Old 07-07-2013, 05:14 PM - Thread Starter
AVS Special Member
 
pdxrealtor's Avatar
 
Join Date: May 2005
Posts: 2,523
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 119 Post(s)
Liked: 143
Quote:
Originally Posted by BIGmouthinDC View Post

Not a true statement. A double breaker intended to squeze two circuits into to the space of a single breaker are on the single leg of the original breaker and provide two entirely separate circuits.
Now a double wide breaker intended to provide 240 will have two legs. The width of the breaker spans the alternating legs.


a double will look like this

681529_front500.jpg

Thank you!

This really is a simple question with one answer. I've read it several times, but can't remember it or seem to find it.

There is one thing you do not want to do when adding breakers, and it has to do with using the same leg, or not. I can't remember.

FS- Netgear 550 .ISO player - PM me
My Gear-Pioneer, JBL Pro Cinema, Fi Car Audio 4- SP4 18", Peavey IPR2 7500 x 4 -Mini-Dsp 4x10, GIK Acoustics, Seymour Screens 110" AT, Dune Smarts, uNraid Server
Theater Build and Two Sono Sub Builds Here-
pdxrealtor is offline  
post #10 of 53 Old 07-07-2013, 05:19 PM
Advanced Member
 
auburnu008's Avatar
 
Join Date: Jun 2004
Location: Auburn, AL
Posts: 852
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Liked: 27
BIG runs this place!

War Eagle!
auburnu008 is offline  
post #11 of 53 Old 07-07-2013, 05:38 PM - Thread Starter
AVS Special Member
 
pdxrealtor's Avatar
 
Join Date: May 2005
Posts: 2,523
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 119 Post(s)
Liked: 143
I find it very odd that one simple question has drawn everything but an actual answer........... so. ... forget it. You all just chat away about breakers and how great people are. I'll figure it out. rolleyes.gif

Good Lord.......

FS- Netgear 550 .ISO player - PM me
My Gear-Pioneer, JBL Pro Cinema, Fi Car Audio 4- SP4 18", Peavey IPR2 7500 x 4 -Mini-Dsp 4x10, GIK Acoustics, Seymour Screens 110" AT, Dune Smarts, uNraid Server
Theater Build and Two Sono Sub Builds Here-
pdxrealtor is offline  
post #12 of 53 Old 07-07-2013, 05:47 PM
AVS Special Member
 
Willie's Avatar
 
Join Date: Jun 2001
Location: The Bay - Green Bay, WI
Posts: 1,264
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Liked: 43
Quote:
Originally Posted by pdxrealtor View Post


So... what do I need to make sure the contractor does to prevent the Hum that could possibly happen if breakers are not installed in a certain way?

Hire a competent contractor. rolleyes.gif
Willie is offline  
post #13 of 53 Old 07-07-2013, 05:49 PM - Thread Starter
AVS Special Member
 
pdxrealtor's Avatar
 
Join Date: May 2005
Posts: 2,523
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 119 Post(s)
Liked: 143
And yet another very insightful answer..... welcome to the club. rolleyes.gif

FS- Netgear 550 .ISO player - PM me
My Gear-Pioneer, JBL Pro Cinema, Fi Car Audio 4- SP4 18", Peavey IPR2 7500 x 4 -Mini-Dsp 4x10, GIK Acoustics, Seymour Screens 110" AT, Dune Smarts, uNraid Server
Theater Build and Two Sono Sub Builds Here-
pdxrealtor is offline  
post #14 of 53 Old 07-07-2013, 06:05 PM
 
gregzoll's Avatar
 
Join Date: Jun 2009
Posts: 2,524
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 32
Big, the top is called a "Tandem" breaker, not a Double. A double pole breaker is one unit that takes up two spaces, a quad takes up four spaces. With a Quad breaker, the top and bottom are tied together, the two middle are tied together. As for the bottom breaker it has nothing to do with 240VAC, that is just an example of a breaker with a handle tie installed. Used for MWBC circuits most of the time, or when people are too lazy to go get a Double pole breaker with a single handle, when wiring in a circuit that requires two legs/poles for the circuit.
gregzoll is offline  
post #15 of 53 Old 07-07-2013, 06:10 PM
AVS Club Gold
 
LeBon's Avatar
 
Join Date: Jun 2006
Location: Pebble Beach, CA
Posts: 719
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 40 Post(s)
Liked: 37
Some experts recommend that your entire system be run from a single "leg" (120 v to neutral). This reduces the chances of a ground loop causing hum or video hum bars. So if you have two 20A circuits for your equipment, they should be connected to the same leg.
LeBon is offline  
post #16 of 53 Old 07-07-2013, 06:12 PM
 
gregzoll's Avatar
 
Join Date: Jun 2009
Posts: 2,524
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 32
Quote:
Originally Posted by pdxrealtor View Post

Lol... so in laymen terms what do I tell my contractor to make sure NOT to do when adding two breakers. The goal being to avoid any HUM noise.
Nothing, other then when they are inside the panel, to check all connections to make sure they are still tight, no corrosion on any bus bars (where the breakers are, and where Neutral & ground connections are connected). Also make sure that there is a proper ground for the panel, and if they have time, double check the CATV or Satellite and Telephone, to make sure they have a proper ground to the Earth ground rod, not just a ground attachment to the outside of the meter pan.

Most towns like mine, have the meter pan bonded to a Earth ground, and inside the structure, the main panel is bonded to the cold water pipe. If you have any break in ground, or say someone took the catv splitters and connected all of them together with a ground wire, instead of using just the first ground block as the only ground point, you can cause ground loops.

It all is about making sure the structure's electrical system is in proper order and all ground connections are good and not corroding, or if someone that did not know what they were doing prior, did not screw things up when they last did anything to the electrical system.

Remember that the weakest point is where you are going to have problems.
gregzoll is offline  
post #17 of 53 Old 07-07-2013, 06:16 PM - Thread Starter
AVS Special Member
 
pdxrealtor's Avatar
 
Join Date: May 2005
Posts: 2,523
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 119 Post(s)
Liked: 143
Quote:
Originally Posted by gregzoll View Post

Big, the top is called a "Tandem" breaker, not a Double. A double pole breaker is one unit that takes up two spaces, a quad takes up four spaces. With a Quad breaker, the top and bottom are tied together, the two middle are tied together. As for the bottom breaker it has nothing to do with 240VAC, that is just an example of a breaker with a handle tie installed. Used for MWBC circuits most of the time, or when people are too lazy to go get a Double pole breaker with a single handle, when wiring in a circuit that requires two legs/poles for the circuit.
If youre so knowledgeable about breakers I find it odd youre not smart enough to figure out what i was trying to say. You are the very last person i would want anywhere near my electrical box. The ability of a skilled trades men to interpret a question such as mine is every bit if not more valuable than text book jargon. But, at least we all know how much knowledge you have.
Quote:
Originally Posted by LeBon View Post

Some experts recommend that your entire system be run from a single "leg" (120 v to neutral). This reduces the chances of a ground loop causing hum or video hum bars. So if you have two 20A circuits for your equipment, they should be connected to the same leg.

Thank you! This is exactly what i wass trying to remember.

FS- Netgear 550 .ISO player - PM me
My Gear-Pioneer, JBL Pro Cinema, Fi Car Audio 4- SP4 18", Peavey IPR2 7500 x 4 -Mini-Dsp 4x10, GIK Acoustics, Seymour Screens 110" AT, Dune Smarts, uNraid Server
Theater Build and Two Sono Sub Builds Here-
pdxrealtor is offline  
post #18 of 53 Old 07-07-2013, 06:18 PM
 
gregzoll's Avatar
 
Join Date: Jun 2009
Posts: 2,524
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 32
Quote:
Originally Posted by LeBon View Post

Some experts recommend that your entire system be run from a single "leg" (120 v to neutral). This reduces the chances of a ground loop causing hum or video hum bars. So if you have two 20A circuits for your equipment, they should be connected to the same leg.
And those so called experts do not have an clue or idea how electrical systems work.

I run everything upstairs on a single 15 amp circuit, downstairs for my networking gear it is a single 15 amp circuit. If you need a 20 amp circuit or multiple 20 amp circuits, you either do not know what you are doing when you do the load calc, or have way too much gear. A poor ground or "bootlegged" ground is two of the reasons why you see problems.

If you want to hear hum during recordings, pull out some of the old Woodstock recordings, or old studio recordings where artists where playing through poor electrical systems. The Woodstock and even Monterey concerts, the electrical systems were so poor and bad grounding when they set the systems up, there is so much hum in the recordings, that the artists used it to their advantage. Especially Jimi Hendrix.
gregzoll is offline  
post #19 of 53 Old 07-07-2013, 06:21 PM
 
gregzoll's Avatar
 
Join Date: Jun 2009
Posts: 2,524
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 32
pdxrealtor, it is the other way around, sorry to say. I have explained to you what can cause hum and problems, but you are looking at the situation the wrong way. And no, if the contractor runs a MWBC (Multi-Wire Branch Circuit) to that room, which they most likely will, you do not want both breakers on the same leg. If you do, you will have more problems than you realize, especially will show during heavy loads, which cause an imbalance on the electrical distribution in the structure.

It is up to you, but your electrician that you hired will know more about installing the circuit than you can learn in five minutes on a forum. I have been doing this stuff over 30 years, and know more about how the system for electrical distribution inside a structure works, along with proper grounding of communication and electrical than you realize.
gregzoll is offline  
post #20 of 53 Old 07-07-2013, 06:36 PM
AVS Club Gold
 
LeBon's Avatar
 
Join Date: Jun 2006
Location: Pebble Beach, CA
Posts: 719
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 40 Post(s)
Liked: 37
Quote:
Originally Posted by gregzoll View Post

And those so called experts do not have an clue or idea how electrical systems work.

Spent 30 years in the TV broadcasting business, built a number of transmission and studio facilities. Have a pretty good knowledge of how electrical systems work.

Your comments are long on generalities, and short on specifics.
LeBon is offline  
post #21 of 53 Old 07-07-2013, 07:11 PM
AVS Club Gold
 
LeBon's Avatar
 
Join Date: Jun 2006
Location: Pebble Beach, CA
Posts: 719
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 40 Post(s)
Liked: 37
I agree that you should not use a Multi-Wire Branch Circuit (MWBC) for this, since you could overload the neutral. I would run 2 separate 12/2 home runs to the load center.
LeBon is offline  
post #22 of 53 Old 07-07-2013, 08:01 PM
AVS Special Member
 
HopefulFred's Avatar
 
Join Date: Mar 2007
Location: Atlanta, GA
Posts: 2,928
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 203 Post(s)
Liked: 226
HopefulFred is offline  
post #23 of 53 Old 07-07-2013, 08:34 PM
Senior Member
 
acras13's Avatar
 
Join Date: Mar 2011
Location: Los Angeles , CA
Posts: 253
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Liked: 15
Quote:
Originally Posted by gregzoll View Post

Incorrect. Does not matter if both breakers are on the same leg if you are using 12/2. What matters is if you are using 12/3 for the two circuits, since both breakers have to be on opposite legs on the panel. Even if you have them on the same leg, using 12/2 you are not going to get hum on the system.

Hum is again caused by poor or incorrect grounding, or poorly maintained electrical systems, not whether breakers are on the same or opposite legs on a panel.


This is a lot of fun , with the OP not trusting a contractor he has hired , asking for help then taking shots at people who are trying to help , OP using wrong terminology to confuse things , and other posters confusing things further by not taking into account they are obviously communicating with someone who knows nothing about electrical systems .
As to the above quote , how do you feed the load from 2 breakers , same leg or different legs , with a 12/2 Romex ? are you suggesting using the bare ground for the neutral? There are 2 insulated wires ( black, white) and a bare ground in Romex , can't feed from 2 breakers in any configuration with 12/2. Now I am pretty sure you meant a 12/2 from each breaker as opposed to using 12/3 Romex , but your above quote is confusing , and I'm sure more so for the uninitiated.
Any configuration of breakers , or Romex the OP has his contractor use that follows code will not inherently introduce hum . As you stated , the interference is introduced by poor connections , corroded connections or a short to ground . Occasionally a motor load will introduce interference or "hum" because of EMF , easiest way to avoid this in a home is to not have your electronics on the same circuit as any kitchen or laundry receptacles.
The exception to this is if the OP is running very sensitive testing equipment , and has multiple frequencies ( 50, 60 Htz.) running parallel , similar to signal wires run parallel to high voltage wires , then EMF can introduce hum into the systems , but I doubt that is the case , otherwise he would most likely be an electrical engineer and wouldn't be here asking the original question.
OP , tell him what your goals for power are , and either trust him or hire someone else. Explain you will want to test your AV setup for " hum" before signing off on the job. He should have no problem letting you test your gear to make sure there's no interference. Unless you hired him from the parking lot of Home Depot , you should be fine . Take a breath , relax and let the man work.

“Loyalty to country ALWAYS. Loyalty to government, when it deserves it.”---Mark Twain
acras13 is offline  
post #24 of 53 Old 07-07-2013, 08:52 PM - Thread Starter
AVS Special Member
 
pdxrealtor's Avatar
 
Join Date: May 2005
Posts: 2,523
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 119 Post(s)
Liked: 143
Listen. First, i appreciate your advice as most of it seems on task.

I can run the wire, install the breakers, and do just about anything else myself.

My contraror is the same contractor who did my gut to studs and put back together remodel. Im as picky as they come, so bet your butt he s worth his salt.

That said, hes a contractor not an audio specialist. He thought he knew what i meant when i said grounds cant be on two differnt legs but wasnt sure. So i said id confirm.

This was a simple question. A very simple question. And look at all the replies!?!?

FS- Netgear 550 .ISO player - PM me
My Gear-Pioneer, JBL Pro Cinema, Fi Car Audio 4- SP4 18", Peavey IPR2 7500 x 4 -Mini-Dsp 4x10, GIK Acoustics, Seymour Screens 110" AT, Dune Smarts, uNraid Server
Theater Build and Two Sono Sub Builds Here-
pdxrealtor is offline  
post #25 of 53 Old 07-07-2013, 09:11 PM
Senior Member
 
cofn42's Avatar
 
Join Date: Sep 2008
Location: Winnipeg, MB
Posts: 359
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Liked: 32
Quote:
Originally Posted by gregzoll View Post

I run everything upstairs on a single 15 amp circuit, downstairs for my networking gear it is a single 15 amp circuit. If you need a 20 amp circuit or multiple 20 amp circuits, you either do not know what you are doing when you do the load calc, or have way too much gear.

I was gonna bite my tongue and just walk away, until I read the above.

Seriously? You are here on a high end audio forum, and you are telling someone they have too much gear?

A 15a circuit can do 1725w.

My 2 amps alone draw 1600w combined. So putting all 3 of them on a single 15a circuit and I would be popping it all the bloody time.

Your advice has been sound until now, but this is completely misleading.

In a place of go big or go home, it sounds like PDX is planning for the future, telling the guy he has too much gear is asinine, and there is a HUGE difference between networking equipment that has little to no draw, vs a high end amp pulling a hundreds of watts....

Marantz AV8801 / Rotel 2x RMB-1095 / RMB-1090 / Yamaha P7000S / Velodyne SMS-1 / DTech BP2000TL / DTech C/L/R 3000 / 4x - DTech BPVX/P Surrounds / DTech SM55 Heights / DTech SM65 Wides / SVS PB13 Ultra / 2x Buttkicker LFE / PTAE-8000U / Globalcache, iRule & Insteon.

Coffin Family Theater Build
cofn42 is offline  
post #26 of 53 Old 07-07-2013, 09:16 PM - Thread Starter
AVS Special Member
 
pdxrealtor's Avatar
 
Join Date: May 2005
Posts: 2,523
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 119 Post(s)
Liked: 143
Greg has been off the mark since post one. While he may be knowledgeable he is far from smart, or he s just being an ass.

FS- Netgear 550 .ISO player - PM me
My Gear-Pioneer, JBL Pro Cinema, Fi Car Audio 4- SP4 18", Peavey IPR2 7500 x 4 -Mini-Dsp 4x10, GIK Acoustics, Seymour Screens 110" AT, Dune Smarts, uNraid Server
Theater Build and Two Sono Sub Builds Here-
pdxrealtor is offline  
post #27 of 53 Old 07-07-2013, 10:13 PM
AVS Special Member
 
Glimmie's Avatar
 
Join Date: Sep 2000
Location: Los Angeles, CA
Posts: 8,018
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 182 Post(s)
Liked: 252
Quote:
Originally Posted by LeBon View Post

Spent 30 years in the TV broadcasting business, built a number of transmission and studio facilities. Have a pretty good knowledge of how electrical systems work.

Your comments are long on generalities, and short on specifics.

And you had all the equipment on the same phase? While I have seen some small facilities in split phase systems, the majority of broadcast plants are three phase. And the idea that different equipment on different phases causes hum is an audiophile myth.

The Directv LA plant has over 2400 racks. 11 megawatts average draw. Do you think that's all on the same phase?

Glimmie's HT Page
Being redone - comming soon!

Glimmie is offline  
post #28 of 53 Old 07-08-2013, 12:42 AM
AVS Special Member
 
Colm's Avatar
 
Join Date: Aug 2002
Posts: 4,652
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 89
Quote:
Originally Posted by gregzoll View Post

...if the contractor runs a MWBC (Multi-Wire Branch Circuit) to that room, which they most likely will, you do not want both breakers on the same leg.
No qualified electrician will do that. You cannot have a MWBC if the two hots are on the same leg. The definition of a MWBC in the NEC includes a voltage between the hots, IOW the two hots are on different legs in a typical residential single phase 3-wire system.
Colm is offline  
post #29 of 53 Old 07-08-2013, 01:06 AM
AVS Special Member
 
scubasteve2365's Avatar
 
Join Date: Jan 2005
Posts: 1,216
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 125 Post(s)
Liked: 253
Quote:
Originally Posted by cofn42 View Post

I was gonna bite my tongue and just walk away, until I read the above.

Seriously? You are here on a high end audio forum,

A 15a circuit can do 1725w.

My 2 amps alone draw 1600w combined. So putting all 3 of them on a single 15a circuit and I would be popping it all the bloody time.

Your advice has been sound until now, but this is completely misleading.

In a place of go big or go home, it sounds like PDX is planning for the future, telling the guy he has too much gear is asinine, and there is a HUGE difference between networking equipment that has little to no draw, vs a high end amp pulling a hundreds of watts....

You're not correct.

1) There is a time domain element.
2) the purpose of the circuit breaker is to protect the wire, not the equipment or load the wire is servicing.
3) you will likely never see a transient 1600W draw.
4) breakers are rated for amperage, not wattage.

Signed,
EE

"The Scuba Tank" thread here
PSN/XBL : ScubaSteve2365
scubasteve2365 is offline  
post #30 of 53 Old 07-08-2013, 01:09 AM
AVS Special Member
 
scubasteve2365's Avatar
 
Join Date: Jan 2005
Posts: 1,216
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 125 Post(s)
Liked: 253
Quote:
Originally Posted by Colm View Post

No qualified electrician will do that. You cannot have a MWBC if the two hots are on the same leg. The definition of a MWBC in the NEC includes a voltage between the hots, IOW the two hots are on different legs in a typical residential single phase 3-wire system.

While I'm hesitant to say never as there always seem to be scenarios one could do what is commonly interpreted to not be permissible, I agree with your post. I only deal with industrial, but if I see a residential feeder with 2 hots I would expect them to be on different legs.

"The Scuba Tank" thread here
PSN/XBL : ScubaSteve2365
scubasteve2365 is offline  
Reply Dedicated Theater Design & Construction

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off