Basement studio in Illinois: I'm on the 10 year plan

[jlehan]

Just got done reading. and reading. and reading about isolated ground receptacles and star grounding. I am absolutely novice when it comes to electrical wiring and such, but I know I need to understand as much as I can to make sure I can guide the folks doing the installs to make sure things are done to spec. My cousing is an electrical engineer and will be helping with design.

At any rate......I'd love to hear from someone who has successfully used star grounding or igr's in a basement or home studio situation that resulted in a successful circuit free of ground loops with minimal to moderate hassle.

I'm also going to be contended wtih dimmer switches throughout the house as well as appliances mixed between legs throughout the electrical panel.

Planning on working up a wiring diagram for review here soon.

[Soundman2020]

I'd love to hear from someone who has successfully used star grounding or igr's in a basement or home studio situation that resulted in a successful circuit free of ground loops with minimal to moderate hassle.

Well, I don't know if this counts, but I've designed and installed dozens of professional video post production facilities using star grounding, from very simple one-room, half-rack setups, to multi-rack, multi-room, multi-story facilities. They all worked. The customers were happy, and there was no hum. I've also been called in to fixed several others that had not been installed by me, and did have hum issues. It is a huge pain to try to track down ground loops: basically, you start by disconnecting everything possible, then re-connecting one by one until the problem appears, then work from there. In a facility with six high-end post suites and two machine rooms, half a dozen full 40 RU racks in each, that can take a while... Much better to plan it right and install it right, from the beginning.

It's no hassle to install star-grounding: I always spec a separate conduit run from the distribution panel to each wall box, and that kind of forces the electricians to get it right! They have no choice. Yeah, it costs a little more in conduit and in extra wire, but you are guaranteed of getting it right. Plus with conduit, it's easy to fix if something did get messed up, even after the walls are sealed and painted...


- Stuart -

[jlehan]

Stuart

I know your codes might be different in your part of the world, but I was wondering if you could share a few more specifics:

i.e. what type of IGRs do you use (plastic? metal boxes), do you run the conduit next to romex or another condiuit, or all in the same conduit? What type of wire do you run? What do you ground back to? A separate panel like in Rod's book?

Thanks!

[Soundman2020]

I know your codes might be different in your part of the world,

Yup! Code here also allows the equivalent of Romex, but I never use that for studios. In fact, I don't even use it at home! It just limits you so much in the future, if you ever need to change anything.

what type of IGRs do you use (plastic? metal boxes),

I'm not sure what you mean by "IGR": I googled it, and only found "Insect Growth Regulator", but that doesn't seem to fit! But if you are asking about the electrical boxes that light switches and electrical outlets go in, then those are plastic here.

do you run the conduit next to romex or another condiuit, or all in the same conduit?

Just conduit. Plain old 20mm PVC electrical conduit (at least 20mm, sometimes much larger). You run it from each wall box direct to the distribution panel. You can buy pre-made curves here, but I usually don't use those as they are normally too tight, making it hard to pull thick cable. So we heat the conduit and bend it into gentle curves, wherever possible. All of the wiring goes on the conduit. We use separate rolls of insulated wire for live, neutral and ground, and pull all three together from the panel to the box. Simple, cheap, effective.

What type of wire do you run?

depends on the circuit, but it could be anywhere from 1.5mm2 to 4.5mm2 for most applications. I occasionally use heavier than that (for example, main power feeds to the panel, or to very heavy loads, such as HVAC), but most of it is in that range. You probably use AWG, not mm2, and I have a table of equivalents somewhere... but you can probably find one on-line. In any event, the wire section is dictated by the circuit load, and since I'm on 220 volts and you are on 110 volt, you can't use my sections to decide on what you need! Your electrician will know what to us, based on the load on each circuit.

What do you ground back to? A separate panel like in Rod's book?

Exactly. I ALWAYS put in a separate panel for technical power, which takes one single feed from the main building panel (hopefully on it's own separate circuit already!). That panel has two separate buses, one for ground one for neutral, where all of the ground and neutral conductors from the outlets go, and of course the live conductors go to the individual circuit breakers. The ground bus is connected to the actual physical ground, which I normally specify as a copper grid outside in the garden somewhere. Normally at least four long copper bars driven deep into the ground (a couple of meters), connected to each other with heavy un-insulated copper wire, and covered with dirt. One single heavy copper wire runs from the grid to the bus, and that is the central hub of your system. Here in Chile we also ground the neutral, so there is actually a heavy link or "bridge" that connects the neutral bus to the ground bus, right there inside the panel. You may or may not have to do that where you are, depending on code. If you can, then do it! Definitely!

So that's all it is, really: a piece of plastic "pipe" (conduit) that runs from each wall box to the distribution panel, and three separate insulated conductors pulled through the conduit, connecting the outlets on one end to the panel on the other. The earth and neutral conductors go to the earth and neutral buses, respectively, and the live conductor goes to its own circuit breaker. Not complex!

Then if you ever need to replace something, it is dead easy. For example, let's say that a year from now you want to install something that you never planned on, and it draws a lot of power, too much for your existing circuit. So just pull out the existing wiring from the conduit, and put in new heavier duty wiring. As you pull out the old wiring, use it to pull through the new wiring at the same time. Replace the circuit breaker with the correct rating for the new circuit, and bingo! You are done! No breaking holes in your drywall, no redecorating, nothing! Just pull the wires through, change the breaker, and that's it!

But check your local electrical code, and see what can be done, You may or may not be able to do it all like this. If you CAN do it this way, then it really is the simplest way of doing it. The only negatives are the slight extra cost for the conduit (a few cents per foot) and a bit of extra labor for installing it. But the benefits far outweigh that, in my experience.


- Stuart -

[jlehan]

Stuart,

wow thanks for the lengthy reply. thats exactly what I was hoping to read.

while I continue to digest...IGR is isolated ground receptacle (sorry, I should have specified): its the "plug" that has a hot, neutral, isolated ground for technical grounding and a ground for the housing itself (2 grounds).

[jlehan]

So I've gone over and over the diagram in Rod's book about star grounding.

I've read the LENGTHY stickies in the foum, but I have a few questions for the experts out there.

1. Lets say I want to use CONDUIT to achieve star grounding, and I decide to put the receptacles IN the wall (not surface mounted), so I build a box around it, caulk it up, etc etc. Since conduit is literally "hard wired" back to the electrical service, do these connections significantly reduce isolation?

2. Lets say I want to run three outlets in series off one breaker from the main panel for the studio, each "star grounded" with its own isolated ground back to the sub-panel and separate ground bus....
a) Would we run conduit run from the service panel to the first isolated ground receptacle box, then the second then the third? Would this conduit contain the common hot and neutral and 3 separate isolated grounds (one per outlet...or one per "plug"?). I assume then at some point a junction boxed would be used to split the isolated grounds off to the second panel and separate ground bus? if so, whats the maximum number of isolated grounds that will fit in one standard-sized conduit (if there is one. They all look the same in my basement now).
b). Is the conduit itself bonded to the isolated ground receptacle as the "safety ground" and the isolated grounds are the "technical grounds". If it is a 4-outlet box, how many isolated grounds run back: 2 or 4?
c). How hard is it to seal up a box with conduit vs. romex when the boxes are IN as opposed to ON the wall?

I apprecaite any feedback: making sure I am giving my electrician the right info.

[Soundman2020]

1. Lets say I want to use CONDUIT to achieve star grounding, and I decide to put the receptacles IN the wall (not surface mounted), so I build a box around it, caulk it up, etc etc. Since conduit is literally "hard wired" back to the electrical service, do these connections significantly reduce isolation?

No, because you follow the same procedure and take the same precautions as for the conduit you use to get your signal cables (snakes) between rooms.

2. Lets say I want to run three outlets in series off one breaker from the main panel for the studio, each "star grounded" with its own isolated ground back to the sub-panel and separate ground bus.... a) Would we run conduit run from the service panel to the first isolated ground receptacle box, then the second then the third?

If the outlets are within a few inches of each other (such as several behind the desk, for example), then just pretend they are all one unit, and bridge all three conductors to all of them, and take a single run of each back to the panel. But if they are more than a few inches apart, then run SEPARATE conduit to each. Yeah, you spend a few more cents on conduit, and a few more dollars on wiring, but if you do that, then you CANNOT get confused and mess up the wiring. It is physically almost impossible. (Unless your electrician is drunk when he wires up the panel!)

Would this conduit contain the common hot and neutral and 3 separate isolated grounds (one per outlet...or one per "plug"?).

You COULD do it that way, but I never would do it that way, for the above reason: each time you make it easy to screw up, then you screw up. Make it hard to screw up. Spend a few extra dollars.

if so, whats the maximum number of isolated grounds that will fit in one standard-sized conduit

What do you mean by "standard sized conduit"? There are several sizes, each one for a different purpose. Here in Chile I can get everything from a practically useless 10mm up to a rather overkill 100mm.

How many conductors you can get in depends not just on the overall diameter: it also depends on the run: how long, how many curves, how tight, etc. You can practically fill the entire diameter of the conduit if you are just going a few inches in a straight line. But You might have trouble just getting your three basic conductors through a very long run with lots of tight turns....(been there, done that!).

b). Is the conduit itself bonded to the isolated ground receptacle as the "safety ground"

Where I live, conduit is plastic: PVC. Grounding it is impossible. Pointless to even think about it. In the USA it is different, with metal conduit being more common. Check your local electrical code to find out what you can and cannot do.

c). How hard is it to seal up a box with conduit vs. romex when the boxes are IN as opposed to ON the wall?

For surface mount, I don't normally use conduit: I use a complete structured system, designed specifically for surface mount, such as Legrand:

http://www.legrand.co.za/en/scripts/en/ ... P=440&L=EN
http://www.legrand.co.za/en/scripts/en/ ... P=448&L=EN
http://www.legrand.co.uk/en/scripts/en/ ... N&SYNC=YES

You can probably find similar stuff where you live. With this system, it's even easier! The ducts snap open along the full length, so you can put the cables in, then snap the cover on again. A bit pricey, though... But very good.

With surface mount, no "sealing up" is required, since there is no wall penetration! You only need to seal up boxes if you had to cut a hole on the drywall and the front of the box sticks through the hole. Surface mount = no holes = no sealing required.


- Stuart -

[jlehan]

Stuart,

As always, thanks for the promp reply! A few follow up questions if I may...

No, because you follow the same procedure and take the same precautions as for the conduit you use to get your signal cables (snakes) between rooms

What procedure is this? I hadn't run across this one yet on the forum or in Rod's book....

If the outlets are within a few inches of each other (such as several behind the desk, for example), then just pretend they are all one unit, and bridge all three conductors to all of them, and take a single run of each back to the panel. But if they are more than a few inches apart, then run SEPARATE conduit to each. Yeah, you spend a few more cents on conduit, and a few more dollars on wiring, but if you do that, then you CANNOT get confused and mess up the wiring. It is physically almost impossible. (Unless your electrician is drunk when he wires up the panel!)

So I THINK what you are saying here is that its easier to do a "Home run" with conduit from each outlet set if possible. I only have 6 open slots on my current service panel, so if I wanted to do more than a couple runs for studio equipment I guess I'd be looking a a completely separate "sub" panel here, correct?

Where I live, conduit is plastic: PVC. Grounding it is impossible. Pointless to even think about it. In the USA it is different, with metal conduit being more common. Check your local electrical code to find out what you can and cannot do

On this note: are you then running 2 separate ground wires back to the panel since the conduit isn't self-grounding?

Again, thanks so much for the sharing. I know there must be severeal ways to skin the cat, so if anyone else has a plan thats worked, I"m all ears!

[Soundman2020]

What procedure is this? I hadn't run across this one yet on the forum or in Rod's book....

Not sure if it's in Rod's book: don't think so. But it's here on the forum, in a few places.

Just like the wall, you have to isolate (decouple) and seal.

The idea is that you cut out small section of the conduit, maybe an inch or so long, at a strategic place where it cross over from the inner leaf to the outer leaf. You wrap that gap with rubber, to decouple the two pieces of conduit. That's the "isolation" part. Now for the "seal" part. Stuff a piece of mineral wool or fiberglass tightly into the end of the conduit (after you get the wires through, of course!) then put a dab of caulk over the end, covering it completely. That way, if you do need to make changes in the future, you can peel pf the caulk, pull out the insulation, and you are ready to go.

So I THINK what you are saying here is that its easier to do a "Home run" with conduit from each outlet set if possible.

That's the idea, yes. It might not always be possible: sometimes you might have to double-up (run two sets of cables through one conduit), but as far as possible, keep things separate.

so if I wanted to do more than a couple runs for studio equipment I guess I'd be looking a a completely separate "sub" panel here, correct?

Personally, I would do that: panels don't cost all that much (at least here they don't: not sure about where you live), and the extra space is welcome! But once again, if you are on a very tight budget then you probably could live with just six runs (doubling-up some if necessary) on your existing panel.

On this note: are you then running 2 separate ground wires back to the panel since the conduit isn't self-grounding?

Only one ground here in Chile: All outlets are double-insulated and the live and neutral "holes" (that take the pins on the plug) are protected by little internal safety flaps that only open when the proper plug is inserted. Since there's nothing metal on the outlet at all (plastic box, plastic conduit, plastic module, plastic faceplate) there's no need to ground it. The only thing grounded is the ground pin itself on the outlet. So there's only one ground conductor on each outlet, not two like you have in the USA. Different systems, different concepts. But what does remain constant, is the need to take a separate run for the ground pins on the outlets: that's the key.


- Stuart -

[gullfo]

best bet is to run a separate sub-panel off a single leg from the main panel. this allows you flexibility in the breaker allocation for the rooms and also puts the studio on the same 120V leg. ideally this leg is not the one you have the rest of the house machinery on (refrigerators, furnace, well pumps, dimmers etc). then between the sub and main is the large ground connection, and from the sub ground strip to each outlet is a home run ground.

[jlehan]

Glenn,

I met with my cousin (an electrical engineer) and the electrician:

We'll be going with that plan. I appreciate clarification. Separate panel, separate home-runs: all is well with the world.

And now....

I have another firestop question...yes yes: i know, I should have thought this through better. But every time I think I understand something, I realize I don't.

It turns out I have to have a gap between the inner and outer leaf that is a little more substantial than I thought it would be. I attached a picture...... The reason it is extra-wide was large drain pipe in the middle of my basement and we were unable to work closer due to obstructions overhead. I know firestopping was discussed previously in my thread and I've looked for what I can find elswhere: anyone have thoughts on firestopping such a large gap with a large intruson through to deal with?

[jlehan]

and on a side note...anyone have a fire-blocking plan for two adjacent walls whose top-plates don't line up well?

thanks!

[jlehan]

4 years, 3 kids (all girls), a growing new business with 15 full time kids, i mean, employees to manage. and hour plus commute very day. I was joking about a 10 year plan originally, but geez. it really might be.

My wife gave me an ultimatum to finish the rest of the basement so the kids will have a place to run around on bad weather days. So that is actually happening: hiring a contractor to finish the "Rec room"

I did get an electrician to rough in the studio along with the rest of the basement. some ups and downs there. We didn't want to cover up the rest in drywall making it difficult to access electrical for the studio.. I decided on plastic receptacles running of a separate subpanel with home runs to each outlet. The studio is probably not getting worked on again for about 6 more months, but i need to make sure a few things are set before drywall goes up in the rest of the basment

So here's my question: We were stuck with some existing conduit, the electrician unknowingly (I say unknowingly because i work an hour commute away and could never be there when he was working, then i missed this until a few weeks later) put the ONE box with conduit in such a way that it is coupling the two leafs together. If the conduit is acting as the ground (and there isn't a separate ground run in there) --this all needs to get ripped out right? If the ground is running in metal conduit itself, I just need to find a way to decouple it.....is that easy/doable?

Hopefully I'll get more and more posted as we keep moving forward!

[jlehan]

this is the switch up the stairs from that conduit: no idea if anyone can tell if the switch is grounded via the conduit/box or if one of the shielded wires might be the ground? or maybe we can't tell at all.....thanks for any input.

[Soundman2020]

Well, I'm not sure how electrical code works in the States, but that switch would NOT pass muster where I live in Chile! Exposed conductors and screws on both sides? Not gonna happen. Instant rejection, right there. (And the electrician would get sent back to school, too!!!) But maybe that's OK under your code, and that isn't your point anyway. Just a comment.


About the conduit: Yes, that's a problem if you are after high isolation. Solid steel mechanical connection.

Here's what I would do:

Conduit-isolation.png

Conduit-isolation-2.png

Conduit-isolation-3.png

In other words, cut a chunk out of the conduit between the two leaves, maybe an inch or so long. Wrap the gap with thick Neoprene rubber, and hold it in place with a couple of electrical cable ties on each side. That takes care of your decoupling, but now you have broken the electrical path too. So get a couple of electrical clamps, like these:

http://www.google.cl/imgres?imgurl=http ... EkQMygkMCQ

Put one on each side of the gap, and run a thick, flexible braided copper strap between them, with a large loop in the middle to ensure your decoupling remains good. Something like this:

http://www.google.cl/imgres?imgurl=http ... F4QMyg5MDk

I'm not sure if that will pass code where you are, but if that deadly dangerous light switch can pass, then pretty much anything can pass!

That's what I would do, and it would pass code here!

By the way, light switches are not normally grounded, so that conduit might not be carrying the ground at all.... But once again, that's where I live, and we don't use metal conduit much any more: it is all PVC here, and the ground is carried by a separate conductor that runs inside the conduit, alongside the phase and neutral conductors.

By the way, congrats on the kids!

- Stuart -