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Service panel in tracking/control room - an issue?
Old 4th December 2013
  #1
Gear Maniac
 
๐ŸŽง 10 years
Service panel in tracking/control room - an issue?

Been doing a substantial basement expansion and reno as detailed here.

This never came up earlier, but now realize that because the new home studio/office space is adjacent to the conduit down from the service head local codes require the service panel to be moved into this room.

It won't really take up too much space, but I'm wondering if having the service panel for the whole house in the same room as mics and recording electronics leads to any known issues. As far as I can tell, the panel itself does not hum. I suppose there might be more EM fields close to the panel, which could create issues with guitar pickups etc.

I just won one small battle related to HVAC in the basement rooms, but then just had to confront this new issue with movement of the service panel (sigh...) The electrician is willing to install isolated ground receptacles in this room, but I'm wondering if people have had issues having the service panel close to a recording location.

pr
Old 4th December 2013
  #2
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AwwDeOhh's Avatar
 
๐ŸŽง 10 years
Since it has to go there anyhow, really only thing is to wait and see.

Worst case, if you're getting EM interference from the box is you could make a mini 'faraday-cage' around the box using copper mesh.
Old 4th December 2013 | Show parent
  #3
Gear Maniac
 
๐ŸŽง 10 years
Quote:
Originally Posted by AwwDeOhh โžก๏ธ
Since it has to go there anyhow, really only thing is to wait and see.

Worst case, if you're getting EM interference from the box is you could make a mini 'faraday-cage' around the box using copper mesh.
Agreed - it's clear there's no choice. Can't believe I didn't think of that (jacked our electricians bill up big time). I actually doubt it will be much of an issue, but will check it out when that happy time comes that the basement is finished. We work a lot with Faraday cages at my research lab job but hopefully won't be needed.

pr
Old 4th December 2013
  #4
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jhbrandt's Avatar
 
๐ŸŽง 10 years
The only issue I have ever seen with a panel in or near the recording area was in a control room where the electrical service for the entire building was on the other side of the wall and analog tape machine was right on the other side. Needless to say, a fair amount of EMI was radiating from the building panels which resulted in a very audible and annoying hum when the machine was switched to play-back off the record head (Sync mode for over-dubs).

The only solution at that time was to turn the machine so that the coils in the head didn't pick up the hum so much. - Similar to moving a Strat around to get less hum.

Other than some kind of single-coil pickup or unbalanced lines, you shouldn't have an issue. We're talking about a residential panel not industrial. More current = more EMI.

I have several articles about studio wiring on my publications page.

Cheers,
John
Old 5th December 2013
  #5
Gear Maniac
 
๐ŸŽง 10 years
Thanks for the reply, John. Will check out your links and hope for the best, and try to deal if otherwise.
pr
Old 5th December 2013
  #6
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JayBeez's Avatar
 
๐ŸŽง 5 years
The service panel for our house is adjacent to my desk / rack (behind a modified cabinet door) and I have a sub-panel mounted to the wall inside (all my electrical is surface mounted). Haven't had any issues whatsoever. Was getting some monitor hum, but went away with a hum eliminator, plugged into a dedicated circuit.
Old 5th December 2013 | Show parent
  #7
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jhbrandt's Avatar
 
๐ŸŽง 10 years
Quote:
Originally Posted by JayBeez โžก๏ธ
....Was getting some monitor hum, but went away with a hum eliminator, plugged into a dedicated circuit.
Which was most likely caused by a ground loop...

Cheers,
John
Old 5th December 2013
  #8
Gear Maniac
 
๐ŸŽง 10 years
Another option

My electrician started this morning and it seems that another option would be to put a main service cutoff switch in the studio space, then run a suitable cable to the panel at its original location (far from the studio). The cost ends up being about the same. I suppose you're basically replacing a a lot of relatively small switches (breakers) and wire pairs fanning out with one big switch and a single larger cable with a lot more current passing through it. I really don't know the real-world implications of that, but perhaps further reading of Johns write-ups will help.

The most vivid demonstration that electrical stuff in the home radiates invisible fields that reach far out into space is definitely when you pick up a single coil guitar and go through the gymnastics to minimize the hum. I had that in my old basement setup, and its probably unavoidable in the real world. I could never figure out what the main source was in my old room.

Thanks again for the comments and advice in the thread,

pr
Old 5th December 2013 | Show parent
  #9
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jhbrandt's Avatar
 
๐ŸŽง 10 years
Quote:
Originally Posted by PhaseRoll โžก๏ธ
....The most vivid demonstration that electrical stuff in the home radiates invisible fields that reach far out into space is definitely when you pick up a single coil guitar and go through the gymnastics to minimize the hum. I had that in my old basement setup, and its probably unavoidable in the real world. I could never figure out what the main source was in my old room.
LOL! There are some places where the ambient (50 or 60 cycle) electrical field permeates everything, everywhere. You can go out in your back yard and still get hum on your strat..

But the strength of field required to generate issues in a properly wired studio is very high.

As far as positioning a sub-panel IN the studio area vs remote switching; Depends. It depends on the number of lines/circuits and how they will be run from the main box. I recommend that all lines going to the studio follow EXACTLY the same path without separating as much as 1 inch. There are grounds in those lines and they will be used to shunt noise current to the ground reference at the service entrance.

Keep all grounds tight together throughout the installation. Read my paper on 'Zero Loop Area'.

I also recommend that you do NOT 'balance' the load at the service for circuits feeding the studio. Run them ALL on only one phase. Balance the load by placing lighting, aux outlets, and ventilation on the other phase.

Cheers,
John
Old 6th December 2013 | Show parent
  #10
Gear Maniac
 
๐ŸŽง 10 years
Quote:
Originally Posted by jhbrandt โžก๏ธ
LOL! There are some places where the ambient (50 or 60 cycle) electrical field permeates everything, everywhere. You can go out in your back yard and still get hum on your strat..
I'm curious now to grab a strat, head out to a field in the middle of nowhere, and plug into a duet on my laptop under battery power, just to hear it through headphones. I don't know if I can even imagine the sound of a single-coil guitar without hum - with my luck it would probably pick up the northern lights...

Quote:
But the strength of field required to generate issues in a properly wired studio is very high.
Single-coil guitars are the only thing I've every encountered that seem able to pick EM fields out of thin air. Everything else always seems to end up being a ground loop.

Quote:
As far as positioning a sub-panel IN the studio area vs remote switching; Depends. It depends on the number of lines/circuits and how they will be run from the main box. I recommend that all lines going to the studio follow EXACTLY the same path without separating as much as 1 inch. There are grounds in those lines and they will be used to shunt noise current to the ground reference at the service entrance.

Keep all grounds tight together throughout the installation. Read my paper on 'Zero Loop Area'.
The studio is spec'ed as having isolated ground receptacles. Do those same directives apply in this case? (are these considered worthwhile?)

Quote:
I also recommend that you do NOT 'balance' the load at the service for circuits feeding the studio. Run them ALL on only one phase. Balance the load by placing lighting, aux outlets, and ventilation on the other phase.
I've asked the electrician to do this - will check on that. I think in my old basement setup this was not done, due to some issues that depended on plug combinations.

Thanks very much for the advice,

pr
Old 6th December 2013 | Show parent
  #11
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JayBeez's Avatar
 
๐ŸŽง 5 years
Quote:
Originally Posted by jhbrandt โžก๏ธ
Which was most likely caused by a ground loop...

Cheers,
John
Indeed !
Old 6th December 2013
  #12
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Rick Sutton's Avatar
 
๐ŸŽง 15 years
The service panel for my building is on the wall about 3 feet from where I sit at the console. Gear all around, over, under, on top of it. 38 years . No issues whatsoever.
Old 6th December 2013 | Show parent
  #13
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jhbrandt's Avatar
 
๐ŸŽง 10 years
Quote:
Originally Posted by PhaseRoll โžก๏ธ
...The studio is spec'ed as having isolated ground receptacles. Do those same directives apply in this case? (are these considered worthwhile?)
It depends. The isolated ground receptacles are required when one uses the metal conduit as safety ground/shielding of the wall outlet and wiring system PLUS a separate ground wire for the equipment that will be plugged into the outlet. It may very well NOT be necessary in your build. The hospital ground type outlets are used for a particular 'system'. They don't make things quieter, they're just part of the design of a system that makes things quieter.

Read all of the papers about these issues on my publications page. ... I was going to point you to one in particular, but they are all important.

Cheers,
John
Old 7th December 2013
  #14
Gear Maniac
 
๐ŸŽง 10 years
Current panel and new receptacles

I posted an entry with pics of the current panel and new receptacles in my studio diary.

The old panel is pretty "busy" with heated floors in two bathrooms, heat pump, and all the 110V circuits throughout the house. Not much choice but to put it in the studio, so will see how it goes - I'm optimistic it won't be an issue.



It looks like all the "isolated ground" receptacles are in place in the studio, and they are all on a single wire, suggesting they'll be on the same leg of the 220V. Will see how it goes...



The receptacle seen in the adjacent room is on a different cable from the ones in the studio.

More than EMI or buzz directly from the panel, my bigger concern is whether the huge hole in the drywall needed for the panel won't be a great point of egress for sound... I'm seeing an expensive acoustically isolated enclosure for this panel in the future.

pr
Old 12th December 2013 | Show parent
  #15
Gear Maniac
 
๐ŸŽง 10 years
Update

Quote:
Originally Posted by PhaseRoll โžก๏ธ
More than EMI or buzz directly from the panel, my bigger concern is whether the huge hole in the drywall needed for the panel won't be a great point of egress for sound... I'm seeing an expensive acoustically isolated enclosure for this panel in the future.
The new panel was put in - it was too crowded down there while the work was happening to take photos and I'm out of town for two days so can't post any pics.

The initial placement of the panel was very low, to avoid the original conduit and some telephone and other low voltage wires that were stuck in place when the foundation company poured the concrete around them (pic taken before the new panel was installed):



This is a classic oversight - the big grey conduit (for service entry) and smaller wires used to be outdoors running along the back of the house. The foundation guys made an "executive decision" to bundle the small wires together along the path of the existing conduit, which was going to have to be eliminated, and pour the foundation around it. Nobody thought to consider that the conduit and cables would have to be moved/decommissioned, and I didn't catch it. Now the routing of those wires (ethernet cable up to second floor, temperature sensor for dual-energy system, cable TV/phone) is literally "cast in stone" and it's not really at an optimal location. The electrician doesn't want to touch the small wires, although the installation of the new panel means decommissioning the old conduit and cables inside.

The electrician then figured that he'd just stick the new panel in below the conduit (which was about to be sheared off, although carefully to avoid impacting the smaller wires). This resulted in the very low positioning of the service panel, which would have put it at a funny height (seems like it should be at about eye level) and also would have made it impossible to put a table flush in the corner of the room (it's not a huge room, and it's likely that at some point it would be desirable to put a piece of furniture right in the corner). I asked them to raise the panel, and although it initially looked like that was going to be an extra grand in time (the hole for the new conduit was already drilled through the foundation wall), they decided they could drill a lower hole in the metal panel box to effectively raise it up by about five inches. At least it should be possible to get a table right into the corner now.

The other thing is that it might make it more complicated to put a bass trap in that corner, although I suppose it won't be impossible. The service panel is now between the two vertical 2x4's visible in the above photo, which is the last pair of studs before the room's corner.

Will post some photos when I get back into town - I'm a bit scared about what's going on now as they're putting in a bunch of cabling and outlets today.



pr
Old 12th December 2013
  #16
Gear Maniac
 
๐ŸŽง 10 years
The new panel

Here's a pic of the new panel (from my diary thread), raised up enough that I could now put a table in the corner if needed. Still wondering if this will be an issue for bass traps - will probably build a small cabinet around the panel.

The pic also shows all the circuits fanning about behind what will be the wall of my studio. If I was paranoid about EMI I'd worry about all those wires... the receptacles in the studio are on their own ground, which has a very short path/big cable as recommended by John.

Old 12th December 2013
  #17
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Rick Sutton's Avatar
 
๐ŸŽง 15 years
Can't you just make the front of the bass trap hinged like a door?

I'm curious as to all the wires fanning out from that panel. What are the red ones and why do some of them travel in front of the studs?
Old 13th December 2013 | Show parent
  #18
Gear Maniac
 
๐ŸŽง 10 years
Quote:
Originally Posted by Rick Sutton โžก๏ธ
Can't you just make the front of the bass trap hinged like a door?
Great idea - thanks!

Quote:
I'm curious as to all the wires fanning out from that panel. What are the red ones and why do some of them travel in front of the studs?
Temporary wires hooked up to heaters to keep our home from becoming a deep freeze during the construction (we're still living upstairs). It's gone down to -20C this last week. All the other wires fanning out behind the studs are just the circuits needed to run a four bedroom house.

There are some pics of the little heaters further up in the thread - they are godawful loud!

pr

Last edited by PhaseRoll; 13th December 2013 at 01:43 AM.. Reason: Clarity?
Old 13th December 2013
  #19
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AwwDeOhh's Avatar
 
๐ŸŽง 10 years
holy cluster of wires!

yes a hinged trap is an option. Or to save on weight on hinges, you can make half of the trap unmovable and the top half hinged. (assuming floor-to-ceiling corner trapping) If you're not doing floor to ceiling, a trap on a stand is an option for that corner.
Old 13th December 2013 | Show parent
  #20
Gear Maniac
 
๐ŸŽง 10 years
Quote:
Originally Posted by AwwDeOhh โžก๏ธ
holy cluster of wires!
Yeah - can you tell we're in Quebec, where everything is electric?

Quote:
yes a hinged trap is an option. Or to save on weight on hinges, you can make half of the trap unmovable and the top half hinged. (assuming floor-to-ceiling corner trapping) If you're not doing floor to ceiling, a trap on a stand is an option for that corner.
Thanks - this will be helpful when I get to that stage!

pr
Old 17th December 2013
  #21
Gear Maniac
 
๐ŸŽง 10 years
Isolated ground receptacles - NOT?!

One of the specifications in our electrical quote was for isolated ground receptacles in the control/tracking room. My understanding of isolated ground is that the receptacles on this circuit have their own dedicated line to ground, typically by a short path using a heavy gauge of stranded cable for low impedance. The electrician had confirmed that these "isolated ground" receptacles would have their own dedicated ground bar driven into the earth right outside the service panel (which is in the room). There is a line item for this in the quote for around $450 + taxes and general contractor overhead.

Today I asked the electrician where he had put the ground bar, and he replied with something like:

Quote:
"oh, well - we couldn't do it like that because when we looked into it we found out it's not allowed - there could be a potential difference between the isolated ground and the main ground. Also it's winter so, you know, it would be hard to get it into the ground. What we did instead was run a single length of 6 gauge cable to the main water entry (at the opposite corner of the house). It should be fine."
The way he described it (I'm paraphrasing and the conversation took place in French), the "isolated ground" receptacles still had their own dedicated ground cable, that was bonded to the water main close the the location where a separate ground cable from the other circuits was attached (not sure whether this would quality as isolated ground). When I looked closely, it was clear that there is only *one* 6 gauge cable running from the service panel to the water main. To me, this is no longer isolated ground and I'm planning to have that expense refunded. Could I be missing something?

I realize that isolated ground may not be necessary in all cases, but given that it was basically new construction I was willing to go for it if it might help debug hum issues down the road. I'm glad I checked while the walls are open - I don't think he's trying to rip me off but also don't think he'd be real motivated to mention this little "deviation".

Any thoughts?

pr
Old 17th December 2013
  #22
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Rod Gervais's Avatar
 
๐ŸŽง 15 years
I do not know anything about the electrical code in Canada - however here in the States he would be correct......... And my best guess is that he is right there as well........

Grounds are required by code to be bonded to the same ground rod - this regardless of whether they are common or isolated.........

Isolated grounds are created by having individual grounds run from the point of use to a point for connecting to that ground source (which here in the states might be either the point of grounding in the main panel or an adjacent isolated grounding panel)

The term "isolated" therefor makes reference to "from one another" - not from the "common point of grounding" itself.

They are merely separate points leading to a common point rather than daisy chained.......

If the ground wires from the receptacles run back to the panel and do not daisy chain in the process (so individual cabling from each receptacle) then he fulfilled his contract with you.

Rod
Old 17th December 2013
  #23
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๐ŸŽง 5 years
Isolated Grounds are not needed when you wire with Romexยฎ Non-Metallic Sheath cable in a wood framed building.

But in an Isolated Ground System: or for that matter a Romexยฎ circuit for your audio equipment.

The Hot, Neutral and IG should have a one to one to one relationship (all in close proximity) to each other all the way from the breaker panel to each outlet box.

The circuit should be planned to reduce the length of wire from outlet box to outlet box.

So how do you do this?

Starting at the breaker box, you run one heavy cable (H, N & IG) to a centrally located junction box, then you star out short runs (H, N & IG) to each outlet box.
Old 17th December 2013
  #24
Gear Maniac
 
๐ŸŽง 10 years
Rod, skate: thanks for clarifications!

pr
Old 17th December 2013 | Show parent
  #25
Gear Maniac
 
๐ŸŽง 10 years
Quote:
Originally Posted by Rod Gervais โžก๏ธ
If the ground wires from the receptacles run back to the panel and do not daisy chain in the process (so individual cabling from each receptacle) then he fulfilled his contract with you.
This seems like the key point - will check. Thanks again.
Old 18th December 2013
  #26
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๐ŸŽง 5 years
There should be only one cable per circuit back to the breaker panel unless that panel is very near the room.

A very good plan for larger rooms is to run one big circuit (40, 60 or 100 Amps) from the main breaker box to a smaller breaker box near the room. Try to reduce the length of power cables from outlet box to outlet box.
Old 18th December 2013 | Show parent
  #27
Gear Maniac
 
๐ŸŽง 10 years
Quote:
Originally Posted by Speedskater โžก๏ธ
There should be only one cable per circuit back to the breaker panel unless that panel is very near the room.
The service panel ended up being in the corner of this this room, which is about 12.5' x 12.5', so I guess that would count as fairly close. It's a small home studio consisting of a single tracking/mix room which will obviously be kind of a compromise on a lot of levels.

Quote:
A very good plan for larger rooms is to run one big circuit (40, 60 or 100 Amps) from the main breaker box to a smaller breaker box near the room. Try to reduce the length of power cables from outlet box to outlet box.
I think this might have been achieved through dumb luck, since the service panel is *in* the room (in the corner).

pr
Old 18th December 2013 | Show parent
  #28
Gear Maniac
 
๐ŸŽง 10 years
Quote:
Originally Posted by Rod Gervais โžก๏ธ
I do not know anything about the electrical code in Canada - however here in the States he would be correct......... And my best guess is that he is right there as well........
Agree it's likely to be virtually identical (although there are also municipal codes here which can add additional requirements that vary considerably).

Quote:
Grounds are required by code to be bonded to the same ground rod - this regardless of whether they are common or isolated.........
That would make sense electrically - it was actually the electrician who said (some time ago) that there would be a dedicated ground rod. It sort of made sense, but I could see where it would create safety issues.

Quote:
Isolated grounds are created by having individual grounds run from the point of use to a point for connecting to that ground source (which here in the states might be either the point of grounding in the main panel or an adjacent isolated grounding panel)

The term "isolated" therefor makes reference to "from one another" - not from the "common point of grounding" itself.

They are merely separate points leading to a common point rather than daisy chained.......
Thanks for clarifying that - we have isolated ground receptacles at work but I've never heard it explained that clearly.

Quote:
If the ground wires from the receptacles run back to the panel and do not daisy chain in the process (so individual cabling from each receptacle) then he fulfilled his contract with you.
It certainly looked like they were daisy-chained - attached is a photo of one of the receptacle boxes with one cable leading (left) back to the box, and the other (on the right) leading to the next box in the chain.

It's harder to tell now with the Roxul and polyurethane insulation in place but I'll check tonight.

Thanks again,

pr
Attached Thumbnails
Service panel in tracking/control room - an issue?-img_4237.jpg  
Old 18th December 2013
  #29
Lives for gear
 
๐ŸŽง 5 years
Ground Rods have nothing special to do with audio quality as it relates to AC power. Every book and paper on the subject has that in the first chapter yet the myth continues.

Ground Rods are for thunderstorms and/or big power company problems.
Old 18th December 2013 | Show parent
  #30
Gear Maniac
 
๐ŸŽง 10 years
Quote:
Originally Posted by Speedskater โžก๏ธ
Ground Rods have nothing special to do with audio quality as it relates to AC power. Every book and paper on the subject has that in the first chapter yet the myth continues. Ground Rods are for thunderstorms and/or big power company problems.
That's lucky for me, because there's two feet of snow on the ground!

Looking back over how this whole "isolated ground" saga, I have to say I've never thought about it much and now I'm not sure how much the electrician really knew about it (I assume it does not come up often in residential construction). It was the electrician who proposed IG receptacles as a "fairly cheap" option given that the walls were open and the room would be used for recording. He was also the one who initially said there would be a dedicated ground rod.

Now I'm wondering if this wasn't just a pointless "upsell" and I'd like to know if anything resembling special ground treatment was even done. If not, then I'd rather not pay for it. If the contractor is representing that IG was done, it would be nice to know what to look for and/or how to test for it. I'm suspecting that a totally standard circuit might work fine from what you say.

I need to read John's articles again. In one of the Jensen documents on grounding they make a compelling/amusing point that aircraft seem to work fine without ground rods pounded into the earth...

pr
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