I'll deal with power first because the audio wiring comes after the power installation and because they both interact we'll sort the power out first. The important thing about power is not
We use balanced and unbalanced leads all the time in the studio but what does it mean? The following diagram illustrates the difference.
Here we have the two standards. The mic lead and the guitar lead. Balanced and unbalanced. Three wire system and two wire system. Note that in the mic lead the positive and the negative don't contact the earth whereas in the guitar lead the negative and the earth are one in the same thing. The earth - (ground) is exactly that. The green earth wire goes to a copper stake in the ground so that any short circuit between the positive and earth will send the current to ground. But because the positive and the negative don't contact the earth it is said to be floating above ground. The shield acts as a protection from interference by sending any extraneous electrical interference like hum, to ground. Unfortunately in the unbalanced circuit negative is ground!
So you would expect that your standard electrical feed from your power supplier would be balanced. Well unfortunately here in Australia it's not. Sure we get a red positive and a black negative from the power companies transformer but by Australian regulations the electrician must link the negative to the earth so we become unbalanced. I understand that is not the system in the US which is why Marshall amps hum in OZ but don't in the US. I would be interested in any information I could receive on this matter from anyone from the US.
STAR EARTHING OF MAINS POWER
In this setup each power point sees the same ground directly and a unit earthed to outlet 1 and connected with a patch lead to something earthed to outlet 2 won't see outlet 2 as it's earth because it has it's own more direct route to ground.
The earth, as stated before, is connected to a copper stake in the ground. It is definitely advisable to increase this factor by getting your electrician to put two or more stakes in the ground and connecting them together to increase your ground connection. I've seen systems where designers have put a whole web of copper stakes under the concrete slab before it is poured to ensure a good ground connection. In this country where it gets very hot the ground around the stake can dry out and the connection gets weaker and weaker. It can be solved to a certain extent by pouring salty water around the stake but two or more stakes is a better solution.
Lighting: It is advisable to have your light circuit separate from your power circuit. This decreases the chance of lighting interference in your power circuits. (See lighting further down this page)
Three Phase Power: Ideally you should have three phase power into your studio. Obviously the home studio owner won't have it but if you are looking at a professional facility it is a beneficial addition. The advantage of three phase power is that you can spread your electrical circuits over the three phases:
Transformer Isolation/Power Conditioning: It is now becoming common to install a power conditioner in a studio. The advantage here is that you have a transformer between you and the supplier so that spikes are smoothed and with additional circuitry you can have a voltage stabiliser that keeps your power voltage stable no matter what the supplier is giving you. You can also have an added feature that adds battery backup in the case of power failure. This is great when you have computers as it allows you to save your current work. All these features are advantageous but can be very expensive! In a three phase setup you can put the conditioner over your equipment and studio power phase only. One of the common annoying items is the fridge. Fridges are prone to sticking spikes in the power so watch out for that one.
detailed info regarding grounding try this excellent web site:
It gets really tricky setting up your earthing requirements but if you start with your mains power installed correctly you've got a better chance when it comes to your audio wiring.
Good lighting is essential in a studio and ideally a separate circuit should be allowed for it. Downlights over the console and effects area are advisable plus additional downlights for the client etc. Lighting dimmers can also make for a comfortable environment but be careful here. You will probably find that the standard light dimmer will cause a buzz interference in your electrical circuits. I suggest you discuss this with your electrician. There are light dimmers available (zero crossing) that don't interfere with your electrics but they can be expensive!! It's not a bad idea to test a few different dimmers before you purchase the full set. In a studio situation you often require full lighting if the musicians are reading charts through to low mood lighting when the vocalist is performing a soft ballad. I believe dimmers are the only way to go.
It's not a bad idea to have control over your studio lights from the control room with a lighting panel mounted somewhere in your control room. That way you can control your lighting from one place.
A recent addition to the lighting system is the 12 volt lighting system. This is a good idea in a studio as these lights are already transformer isolated through the power supply which delivers the 12 volts.