Members 144dB Posted July 14, 2012 Members Share Posted July 14, 2012 Hey all, I recently moved and I'm in the process of laying out my home studio. It's not as large as my prior room, but there are trade-offs in life that are unavoidable. It's a house built in the 1940's, and not surprisingly, many of the outlets are not grounded. I'm hiring a Master Electrician to do some upgrades and code-related fixes, and I need some advice to get the best clean power in that studio room, as well as limit the possibility of ground loops. I know there are some electricity-savvy folks in this forum (Mike Rivers comes to mind), so I figured it would be an appropriate post. My studio setup is a horseshoe layout, and I'll have a high powered PC (650W PSU, 10-11A draw), two LCD's, a Mackie compact mixer, a headphone amp, a sound module, and a MIDI interface on one outlet (with a surge suppressor). I'll have another outlet on a different wall powering my two synths and a knob controller. And finally, an outlet on a third wall will power my powered monitors (Event PS-8's). Lighting is primarily from a ceiling fixture. None of the existing room outlets are grounded, so I'm thinking about putting in a new isolated, grounded 20A outlet to support the PC, displays, mixer, etc. The question I have is what is the best solution for the other two outlets to minimize AC noise and maximize safety, etc. One option would be to put all three outlets (all gear) on one isolated 20A circuit with a common ground. Another would be to put all of the outlets on separate isolated grounds (if I'm understanding my electrician correctly). And I'm sure there are other combinations and possibilities that I'm not thinking of. I need to calculate the full load for the room, as 20A may not be sufficient. The house has good 100A service and a decent panel, and my electrician inspected the existing wiring and connections, and with a few minor exceptions, the electrical was done properly. It just isn't necessarily up to snuff for a project studio. I'll read as much as I can over the weekend (and consult Rod Gervais's book), and I won't commission the work until I know what the best solution is. But any advice is appreciated. I tried three electricians and I really like this guy (30+ years experience plus experience with wiring corporate computer/server labs), but he needs some input on what my actual needs are, and I need some input from you guys on strategy, recommendations, etc. Unfortunately I just don't understand home electricity as much as I would like. Thanks in advance. Todd Link to comment Share on other sites More sharing options...
Members philbo Posted July 14, 2012 Members Share Posted July 14, 2012 One thing to ask is to make sure all outlets are on the same leg of the 220VAC (110V power can be gotten from either leg of a 220V split-phase source). Yes, an isolated ground for each outlet is a great idea also. Ask to make sure each outlet runs directly to the breaker box, rather than possibly being used to feed other loads. In particular, the neutral line should not be shared or connected to any other circuit outside the breaker box. You could ask to have the romex or wires for each outlet run through a dedicated metal conduit for shielding (this could get expensive and messy if it has to be pulled through existing walls). It would be good to add surge protection in the breaker box for the dedicated studio circuits. Actually, a whole-house surge protector is a good idea also. If you want to throw some serious money at it, you could have him install balanced 110V power. This is basically a huge isolation transformer with a faraday shield, sized maybe 4 or 5 KVA (roughly twice your expected load), upstream from the dedicated studio breakers, where the secondary winding center tap is connected to ground, so each secondary leg is 55VAC). Code may require a separate breaker box for it, but I'm not positive (a separate box wouldn't hurt, and would prevent a future homeowner from rededicating it to, say, running a small welder or something else it's not designed for). This is probably overkill, though... Link to comment Share on other sites More sharing options...
CMS Author MikeRivers Posted July 14, 2012 CMS Author Share Posted July 14, 2012 10A for a computer? Really? Unless you're running audiophile single tube class A amplifiers for your monitor or you plan to have a wall full of instrument amplifiers in the room, a single 20A circuit is usually fine. You might want to splurge and have two outlets installed on adjacent walls just in case you decide you want to rearrange things in a couple of years, or months. Get 4 outlets mounted in quad boxes so that you can "star" your power out to different locations. Good quality outlet strips will be fine for distribution within the room. Link to comment Share on other sites More sharing options...
Members 144dB Posted July 15, 2012 Author Members Share Posted July 15, 2012 Hi Guys, Thanks for the input. Funny enough, Philbo was the other user I was thinking of when I wrote the post. This subject matter is so foreign to me, so it's hard for me to communicate and translate it clearly. I should note that when I said that the outlets would be on an isolated ground, that's not really the case. Said another way, there won't be a copper spike the ground for each outlet. I believe the electrician was referring to IGR or isolated grounding receptacles, because the cost difference for materials and installation wasn't substantial (just a bit more for the outlets and a bit more for the wire in cost per foot). I did a little bit of reading on IGR, and one article claims that it only provides benefit 50% of the time (and actually worsens the noise level 50% of the time), and it's really only effective for long runs. I don't know if this is true or not. The distance between these new outlets and the panel is perhaps the shortest in the house (the room is almost directly above the basement area where the panel resides). Does IGR make sense for a small home studio, and is this synonymous with what you meant by an isolated ground (Philbo)? I found a similar thread at GS about oulets here. I can't really run steel conduit in this house due to wall constraints, plaster walls, etc. Philbo: What would be the approximate cost for a surge protector at the panel (for a typical 100A service)? Any guesses? I will ask my electrician as well. Mike: The 10A to 11A figure comes from the PSU specs, which probably aren't reflecting what the PC is actually consuming. But a 650W to 750W capacity PSU will typically list the input current in the 10A to 12A range (e.g. Antec, Enermax, etc.). I'm going to inspect all of the pieces in my studio to see what the max amperage is for the room, and then allow for some overhead. I hope I don't have to go higher than 20A, but that would seem unlikely. I ran all of this gear in a single apartment bedroom for 10 years without any regard for power, and I never ran into any shortages. My electrician recommended a 15A circuit, but primarily because the romex is a bit easier to work with. He thought 20A was overboard, but I always like to provide some headroom. He did say that a high amp circuit could result in a "fill issue" at the panel, but I don't know what that means. I don't think he was referring to the number of available breakers. I think he meant something else. In terms of actually plugging the gear in, I usually put a high quality surge suppressor into one plug and connect all gear to it (i.e. all gear that is destined for that outlet). Even if I put a quad outlet into one location, I would only use one plug. I come from a mindset that says that I should never plug a device directly into an outlet, and that it should always be run through a surge suppressor/spike protector first. Maybe this is sub-optimal in terms of distribution. I don't know... In my room, one outlet and plug would feed the PC, LCD displays, a sound module, a headphone amp, a Mackie 14 channel compact mixer, and a MIDI interface. Another wall/outlet/plug would feed my two synths and a knob controller. And another wall/outlet/plug would feed my powered monitors, and if I have a client in the studio with an amp, usually the powered monitor outlet would be used (though not typically at the same time since we use headphones). More often that not I'm using a DI anyway... One last dumb question: Regardless of the amount of amperage I install, I'm still only paying the electric utility company for what I consume, correct? In other words, I could put a 25A circuit in that room, but if I'm only consuming 15A, I'm only paying for 15A correct? Thanks again, Todd Link to comment Share on other sites More sharing options...
Members UstadKhanAli Posted July 15, 2012 Members Share Posted July 15, 2012 For one of my home studios, my friend, who is a licensed electrician, put in an 8-ft. copper ground rod, which seemed to help. I mention this in case it helps. You basically take a copper ground rod and pound it almost eight feet into the ground, and that's your ground. I also use a line voltage conditioner/regulator in my studio. Link to comment Share on other sites More sharing options...
CMS Author MikeRivers Posted July 15, 2012 CMS Author Share Posted July 15, 2012 I should note that when I said that the outlets would be on an isolated ground, that's not really the case. Said another way, there won't be a copper spike the ground for each outlet. I believe the electrician was referring to IGR or isolated grounding receptacles, because the cost difference for materials and installation wasn't substantial (just a bit more for the outlets and a bit more for the wire in cost per foot). The difference between these receptacles and the ones that cost a dollar or so at Home Depot is that the ground screw in a conventional outlet is mechanically connected to the mounting bracket of the outlet which, in turn, is connected to the metal box that mounts the outlet to or in the wall. It allows you to run a separate ground wire to each outlet in a group that's fed from a single breaker, but that requires running a separate 3-conductor cable from the outlet to the breaker. It might be worth while using those outlets if you install a sub-panel, for example a box with two 15 or 20 amp breakers, in the studio, and then run each outlet with its own ground back to the panel. But if you're just running one circuit from the main panel to the studio room and wiring it to a couple of outlets, then there's no reason to isolate the ground wiring. The other "isolated" wiring that people talk about for studios is using an isolation transformer between the main panel and the isolated outputs. In this system, neither pin of the outlet is connected to "neutral." This gives you the same sort of advantage as a balanced audio connection, which can cancel out noise that's carried along the power line. Neutral (the "low" side of the power line) is bonded to ground (the dirty brown stuff under the house) through a single wire at a single point in the main breaker box. You can drive your own ground stake if you wish (at least in places where this complies with the local building code) but you can't have two "grounds." And even more important, you can't put your studio outlets on their own ground stake. It must be connected to the ground bus that's bonded to the power neutral. This for normal electrical safety, and also for fire safety. If there's a lightning strike nearby, there can be a substantial current in the earth ground, which means that there will be a potential difference between the two grounds that may be several thousand volts which has been known to pump enough current through the home ground wiring to overheat the conductors and start an electrical fire. Hopefully this wasn't the cause of Ken's house fire. It will invalidate your home insurance coverage. The 10A to 11A figure comes from the PSU specs, which probably aren't reflecting what the PC is actually consuming. But a 650W to 750W capacity PSU will typically list the input current in the 10A to 12A range (e.g. Antec, Enermax, etc.). I'm going to inspect all of the pieces in my studio to see what the max amperage is for the room, and then allow for some overhead. The actual current is probably about half that maximum value, but then I'm still living in the world of computers with 300 watt power supplies that draw about 2A in actual operation. Modern power supplies are very efficient If you just start adding up nameplate or spec sheet data you'll probably come up with about twice the capacity you need. Better to buy or borrow a clamp-on ammeter and just go around checking things that draw more than a trivial amount of current. I think that even with your speakers cranked pretty loud, you won't exceed 15A, which is a good reason to install a 20A circuit or two, since you have a fairly short run. My electrician recommended a 15A circuit, but primarily because the romex is a bit easier to work with. He thought 20A was overboard, but I always like to provide some headroom. He did say that a high amp circuit could result in a "fill issue" at the panel, but I don't know what that means. I don't think he was referring to the number of available breakers. I think he meant something else. You can put more than 100A worth of breakers in a 100A service box on the assumption that not all of them will be loaded to their rated capacity at the same time. For example, you could put eight 15A on a 100A service, but you might not be able to use six 15A and two 20A breakers. I'm sure there's a formula for it. (not official electrical code nubmers - ask your electrician) In my room, one outlet and plug would feed the PC, LCD displays, a sound module, a headphone amp, a Mackie 14 channel compact mixer, and a MIDI interface. Another wall/outlet/plug would feed my two synths and a knob controller. And another wall/outlet/plug would feed my powered monitors, and if I have a client in the studio with an amp, usually the powered monitor outlet would be used That sounds like a good case for a 20A or so sub-panel in the studio with feeding two circuits. But like you, I've had everything in my studio plugged into the outlets that are convenient (they're on two 15A circuits, but lights are on those same circuits) and never had a problem. I'm still only paying the electric utility company for what I consume, correct? In other words, I could put a 25A circuit in that room, but if I'm only consuming 15A, I'm only paying for 15A correct? Right. You pay for what your electric meter says you used, and unused outlets don't draw any current. Link to comment Share on other sites More sharing options...
Members UstadKhanAli Posted July 15, 2012 Members Share Posted July 15, 2012 And even more important, you can't put your studio outlets on their own ground stake. It must be connected to the ground bus that's bonded to the power neutral. This for normal electrical safety, and also for fire safety. If there's a lightning strike nearby, there can be a substantial current in the earth ground, which means that there will be a potential difference between the two grounds that may be several thousand volts which has been known to pump enough current through the home ground wiring to overheat the conductors and start an electrical fire. Hopefully this wasn't the cause of Ken's house fire. It will invalidate your home insurance coverage. That was several houses ago, and never caused a fire or any issues. And the guy was a licensed electrician, so I am confident that it was done correctly. We almost never have lightning storms (and the few times this occurred, I disconnected my equipment), and a grounding rod is buried in the ground 8 ft. or more, with almost nothing sticking out of the ground and situated next to the house, and is compliant with the CEC (California State Electrical Code) and NEC. YMMV. If this is still faulty wiring, then you are basically saying that the CEC and NEC are wrong, in which case I have to toss my hands in the air and say I don't know. My garage fire started by potting soil inside the garage spontaneously combusting on an 85-degree day in May at 1:00 am. Link to comment Share on other sites More sharing options...
Members Huh? Posted July 15, 2012 Members Share Posted July 15, 2012 I got an extremely short fuse.......whaddya want to know? Link to comment Share on other sites More sharing options...
Members philbo Posted July 16, 2012 Members Share Posted July 16, 2012 Hi Guys, Thanks for the input. Funny enough, Philbo was the other user I was thinking of when I wrote the post. This subject matter is so foreign to me, so it's hard for me to communicate and translate it clearly. I should note that when I said that the outlets would be on an isolated ground, that's not really the case. Said another way, there won't be a copper spike the ground for each outlet. I believe the electrician was referring to IGR or isolated grounding receptacles, because the cost difference for materials and installation wasn't substantial (just a bit more for the outlets and a bit more for the wire in cost per foot). I did a little bit of reading on IGR, and one article claims that it only provides benefit 50% of the time (and actually worsens the noise level 50% of the time), and it's really only effective for long runs. I don't know if this is true or not. The distance between these new outlets and the panel is perhaps the shortest in the house (the room is almost directly above the basement area where the panel resides). Does IGR make sense for a small home studio, and is this synonymous with what you meant by an isolated ground (Philbo)? I found a similar thread at GS about oulets here. I can't really run steel conduit in this house due to wall constraints, plaster walls, etc. Philbo: What would be the approximate cost for a surge protector at the panel (for a typical 100A service)? Any guesses? I will ask my electrician as well. Mike: The 10A to 11A figure comes from the PSU specs, which probably aren't reflecting what the PC is actually consuming. But a 650W to 750W capacity PSU will typically list the input current in the 10A to 12A range (e.g. Antec, Enermax, etc.). I'm going to inspect all of the pieces in my studio to see what the max amperage is for the room, and then allow for some overhead. I hope I don't have to go higher than 20A, but that would seem unlikely. I ran all of this gear in a single apartment bedroom for 10 years without any regard for power, and I never ran into any shortages. My electrician recommended a 15A circuit, but primarily because the romex is a bit easier to work with. He thought 20A was overboard, but I always like to provide some headroom. He did say that a high amp circuit could result in a "fill issue" at the panel, but I don't know what that means. I don't think he was referring to the number of available breakers. I think he meant something else. In terms of actually plugging the gear in, I usually put a high quality surge suppressor into one plug and connect all gear to it (i.e. all gear that is destined for that outlet). Even if I put a quad outlet into one location, I would only use one plug. I come from a mindset that says that I should never plug a device directly into an outlet, and that it should always be run through a surge suppressor/spike protector first. Maybe this is sub-optimal in terms of distribution. I don't know... In my room, one outlet and plug would feed the PC, LCD displays, a sound module, a headphone amp, a Mackie 14 channel compact mixer, and a MIDI interface. Another wall/outlet/plug would feed my two synths and a knob controller. And another wall/outlet/plug would feed my powered monitors, and if I have a client in the studio with an amp, usually the powered monitor outlet would be used (though not typically at the same time since we use headphones). More often that not I'm using a DI anyway... One last dumb question: Regardless of the amount of amperage I install, I'm still only paying the electric utility company for what I consume, correct? In other words, I could put a 25A circuit in that room, but if I'm only consuming 15A, I'm only paying for 15A correct? Thanks again, Todd Mike Rivers did a great job addressing everything. FWIW, my studio runs off a single 15A outlet feeding 2 separate power strips (one in each receptacle of the outlet). Costs on whole house surge protectors. Link to comment Share on other sites More sharing options...
Members JeffLearman Posted July 16, 2012 Members Share Posted July 16, 2012 I can't imagine you needing more than 15 amps. We've run our whole sould band, driving about 2KW for mains & monitors, 750W for keyboard monitors, plus bass amp & guitar amp. Of course, those are "rated max output" watts for the amps, and the average draw at 110V would be substantially less -- but it's way more than than you have in your studio, even with that behemoth computer. I admit we had more than I felt comfortable on one 15A circuit; I usually prefer 20A which we've used plenty of times. But it was a private party and that's what was available, and it worked with no observable issues. Philbo says you want separate circuits for each receptacle, but I don't understand why. I would think that to minimize ground loops, you want all receptacles to share the same ground as close as possible. That is, run the one circuit, with the feed to the center receptacle and branch out to the two sides. Alternatively, run to a sub panel and branch from there (if you need more than one circuit to handle the draw). If all your gear is properly built and designed and connected, you shouldn't have ground loop problems anyway -- at least in theory. But I believe it's still best to minimize in case you do have issues. Link to comment Share on other sites More sharing options...
CMS Author MikeRivers Posted July 16, 2012 CMS Author Share Posted July 16, 2012 Philbo says you want separate circuits for each receptacle, but I don't understand why. I would think that to minimize ground loops, you want all receptacles to share the same ground as close as possible. Well, the way to do that if you're using isolated ground receptacles is not necessarily to put each one on a separate circuit, but to run each one back to the breaker box so your common ground point is there, where it's bonded to neutral. If you daisy chain grounds between outlets, that's where you can invite ground loops. I think I have an article about power distribution and protection on my web page. If I don't, bug me and I'll dig it out and put it up there. I know I wrote an article for Recording on the subject about 15 years ago. Link to comment Share on other sites More sharing options...
Members blue2blue Posted July 16, 2012 Members Share Posted July 16, 2012 Mike Is it safe to say that your primary focus is preventing any device from seeing multiple routes to ground through any connection, power or signal? Link to comment Share on other sites More sharing options...
Members philbo Posted July 16, 2012 Members Share Posted July 16, 2012 I can't imagine you needing more than 15 amps. We've run our whole sould band, driving about 2KW for mains & monitors, 750W for keyboard monitors, plus bass amp & guitar amp. Of course, those are "rated max output" watts for the amps, and the average draw at 110V would be substantially less -- but it's way more than than you have in your studio, even with that behemoth computer. I admit we had more than I felt comfortable on one 15A circuit; I usually prefer 20A which we've used plenty of times. But it was a private party and that's what was available, and it worked with no observable issues.Philbo says you want separate circuits for each receptacle, but I don't understand why. I would think that to minimize ground loops, you want all receptacles to share the same ground as close as possible. That is, run the one circuit, with the feed to the center receptacle and branch out to the two sides. Alternatively, run to a sub panel and branch from there (if you need more than one circuit to handle the draw).If all your gear is properly built and designed and connected, you shouldn't have ground loop problems anyway -- at least in theory. But I believe it's still best to minimize in case you do have issues. I was working from the OP by 144dB, where he said he was planning on getting 2 duplex outlets. Link to comment Share on other sites More sharing options...
Members ggm1960 Posted July 16, 2012 Members Share Posted July 16, 2012 I remember when I moved into the old house that I recently vacated my first project was to set up most of the modest basement space for my home studio. Like a lot of old houses there wasn't much for plug-ins down there, just a couple that where built into the light sockets. Fortunately the house had been updated at some point and had a modern breaker switch fuse box located close to where I intended to have my center of operations. It wasn't a whole lot of work to plug in a 20 amp breaker and run wiring along with 5-6 outlets throughout the basement. I started out with the flexible metal cable style wiring and for the last couple outlets I reduced it to normal white wire seen in most homes. I also ran the tools at my work bench from the same circuit but that wasn't a problem because I'm not flexible enough to be grinding, drilling and sawing at the same time I'm playing keyboards, guitar or recording vocals. Link to comment Share on other sites More sharing options...
CMS Author MikeRivers Posted July 16, 2012 CMS Author Share Posted July 16, 2012 MikeIs it safe to say that your primary focus is preventing any device from seeing multiple routes to ground through any connection, power or signal? Yes, that's the consideration for hum and noise reduction. The issue of safety with multiple ground points separated by some earth is a safety issue. Link to comment Share on other sites More sharing options...
Members 144dB Posted July 17, 2012 Author Members Share Posted July 17, 2012 Are there any downsides to IGR receptacles? I've never been in a house that has had them, but for resale purposes, etc., are they a problem? Could a future homeowner use them for any general purpose, or do they have limitations? They look a bit odd (the orange receptacle, etc.), but to a layman, are they still just an electrical outlet? Thanks in advance. Todd Link to comment Share on other sites More sharing options...
CMS Author MikeRivers Posted July 17, 2012 CMS Author Share Posted July 17, 2012 Are there any downsides to IGR receptacles? I've never been in a house that has had them, but for resale purposes, etc., are they a problem? Could a future homeowner use them for any general purpose, or do they have limitations? They're fine as long as they're installed properly. If somebody doesn't like the orange, they (or you) can always exchange them for standard home style receptacles. The wiring will be the same and they'll still be legal. Link to comment Share on other sites More sharing options...
Members JeffLearman Posted July 17, 2012 Members Share Posted July 17, 2012 I was working from the OP by 144dB, where he said he was planning on getting 2 duplex outlets. OK, but I still don't get it. The original question included the simple option; isn't it the best one? (Using the same 20A circuit to feed the additional two outlets. PS: I'd use quads rather than duplex.) Link to comment Share on other sites More sharing options...
CMS Author MikeRivers Posted July 17, 2012 CMS Author Share Posted July 17, 2012 But is there any advantage to isolated grounds, for audio? I would think that the simplest solution would also be the best: just use one circuit for all 3 receptacles, without isolated grounds. Using isolated grounds *increases* the length of any ground loop. What's the benefit to that? There's no clear "best" here. The benefit to using isolated ground receptacles is that you can have true star grounding, the center of the star being the point where ground and neutral are tied together. But that only lasts as long as you only plug one device into each outlet. Once you plug in two devices, particularly two devices that are connected together with shielded cable where the cable shields are connected to the device's internal ground (as they should be) then you have a ground loop. In real life, you have ground loops. No getting around it. The thing is that because of the way a device's internal grounding path is designed (or not designred), some devices don't care about a ground loop because the ground loop current won't go anywhere near the signal path. But if the ground current affects the power supply, as it can with a high (that's more than a few tenths of an ohm) resistance between the shield connection and the signal ground, that's when you get hum, that's usually (at least on forums) called a ground loop problem. It's really a "pin 1" problem. The best answer, I think, is that there isn't going to be any significant difference however you wire it, unless you have some crappy gear that's going to be affected by a ground loop no matter what you do short of breaking a ground connection. You can lift the shield at one end, but then you leave a hole where EMI can get in, and there's more of that floating around a studio than ever today. Or you can lift the safety ground pin and take a chance (admittedly a small one) on getting electrocuted. Link to comment Share on other sites More sharing options...
Members JeffLearman Posted July 17, 2012 Members Share Posted July 17, 2012 Why is there an advantage to a star versus a tree? In either case, there are no ground loops. (And in either case, if two units are connected by a signal common, there is a loop.) Seems to me the tree would be better than the star, because if the two units connected by a signal common are on the same tree branch, the ground loop is smaller than with a star. Thanks. The best answer, I think, is that there isn't going to be any significant difference however you wire it, unless you have some crappy gear that's going to be affected by a ground loop no matter what you do short of breaking a ground connection. You can lift the shield at one end, but then you leave a hole where EMI can get in, and there's more of that floating around a studio than ever today. Or you can lift the safety ground pin and take a chance (admittedly a small one) on getting electrocuted. This I understand and agree with, but Les Harvey might disagree with the small chance. Link to comment Share on other sites More sharing options...
CMS Author MikeRivers Posted July 17, 2012 CMS Author Share Posted July 17, 2012 Why is there an advantage to a star versus a tree? I think that what you're calling a "tree" is actually a star configuration - a bunch of plugs going into a bunch of outlets all connected in parallel. The difference between this and a true star configuration is that instead of all the grounds going to a single physical point, they're distributed over the length of the wiring between outlets. If you had four pieces of gear and a quad box, you'd really have a star because off the gear grounds would be common in that box. What you want to avoid is a few outlets on a daisy-chained ground each connected to a crummy outlet strip or two. It doesn't take very much resistance to cause trouble if you have a ground loop. Seems to me the tree would be better than the star, because if the two units connected by a signal common are on the same tree branch, the ground loop is smaller than with a star. I guess that might be true, assuming you had good outlets and good connections to them. But what happens when you have another piece of gear that's connected to a different outlet through its power plug, but is also connected through a cable shield. Link to comment Share on other sites More sharing options...
Members JeffLearman Posted July 17, 2012 Members Share Posted July 17, 2012 OK, I see your point that contact resistance is a bigger factor than conductor length! Thanks. Link to comment Share on other sites More sharing options...
Members 144dB Posted July 19, 2012 Author Members Share Posted July 19, 2012 A question for curiosity only: If I walked into a professional, large-scale studio (e.g. Oceanway, Abbey Road, etc.), would I see orange IGR receptacles, or are they more common in computer server rooms and hospitals? Just curious... Todd Link to comment Share on other sites More sharing options...
CMS Author MikeRivers Posted July 19, 2012 CMS Author Share Posted July 19, 2012 You might see some isolated outlets, but they wouldn't be for the regular studio equipment, they would be for visitors. I think the main reason why the outlets are orange is so that a janitor in a hospital doesn't unplug whatever's plugged into a convenient outlet and plug in the floor polisher. Link to comment Share on other sites More sharing options...
Members 144dB Posted July 24, 2012 Author Members Share Posted July 24, 2012 Hey all, I updated the statement of work for my electrician, and I should have a quote in a couple of days. I decided to put a dedicated circuit into my studio (at least 20A), and route it to three IGR outlets. The isolated ground from each outlet will be joined at a common, auxiliary ground buss bar (probably in a small sub-panel), and then tied into the main ground bar at the main panel. In other words, the IGR outlet grounds will be summed at one point, prior to joining the main ground. It also looks like I can keep my gear away from the major appliances power-wise (most of my appliances are on the "even" leg of the box, whereas my studio circuit will be on the "odd" leg). The existing outlets will remain in that room (though they won't likely be used), but that existing circuit will be used for the lighting, etc. And there won't be any dimmers in my studio. There are only two issues that remain: I added up my amperages, and if I apply the 80% rule to the breaker capacity, I'll exceed a 20A circuit. But that's all based on the assumption that a high-end PC draws 10 amps, and that just doesn't sound right. And based on all of the prior feedback, it isn't right. My powered monitors are about 2 amps combined, my LCD screens are 3 amps, my synths, mixers, and modules are almost nothing, and the computer is 9 to 10 amps based on the power supply rating. I tried adding up individual internal PC components, but many of them don't report amperage, and I'm not sure if the wattage is based on the PSU rails, or based on the wall voltage (120V). For example, the CPU (Core i7 Ivy Bridge) is 77W, but I don't know if I should divide that by 120V, or divide it by the rail of the PSU that it is tied to (12V, 5V, or 3.3V). I don't have my new PC yet, so it's not as simple as slapping on an ammeter to find the true draw. I'm debating bumping the circuit to 25A (if feasible), or adding two 20A circuits for that room (which my current panel may not support). Or I can just shut up and assume that a DAW PC won't draw anywhere near 9 or 10A. The other issue is the isolated ground for the IGR receptacles... If I'm going to the trouble of adding a secondary ground buss bar, then I would expect each outlet to run a discreet, isolated, dedicated ground wire to that ground bar. But my electrician says that they generally run a common ground wire for the three outlets. If a single ground wire is run to the room for the isolated grounds, then installing a secondary ground bus bar seems pointless. By my simple logic, the summing of the grounds is already occurring through the common wire. He may have been referring to the non-isolated ground wire, but I'll have to double check. Mike / Philbo: Does this make sense? Should the isolated ground wires for each outlet be fully independent of one another until the reach the ground buss bar? Or is sharing a common ground wire acceptable? Thanks in advance. Todd Link to comment Share on other sites More sharing options...
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