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i have an out building on the property, it has electricity. but i have no idea about the wiring or how its setup.

there are plenty of outlets and lights. But i will assume since there is no panel/breaker box any where that the building is wired up in a manner that one line is coming in to the building and then jumpered around to outlets and light sockets and fluorescents.

i will be using the building a a rehearsal & recording space. therefore, after removing some of the unnecessary pulls.

i was wondering is there anyway i can ground the outlets that my musical gear and recording equipment is plugged into so there is no buzzing or hum coming through the amp and recorder?

any help would be greatly appreciated. i have a basic knowledge of how to add and remove outlets, switches & etc. but nothing professional. but will have a "electrician" come by and make sure i won't wind up burning the place down! thanks future noise!

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    If you have other musicians coming to the building (and definitely if you're renting the space out), then I'd recommend a survey by a real electrician to check the size of the cable coming from the main building, and maybe rewire the whole building, just for insurance's sake.
    – PeteCon
    Oct 28, 2016 at 16:44
  • thanks pete, well itll be a mostly private space, nothing needing to bring the man in on, i mean im on some land in WV.. the biggest worry is the pill heads, and buzzing on the recordings. thanks! Oct 29, 2016 at 12:06
  • Have you ever heard the term "pin 1 problem", btw? Oct 29, 2016 at 17:56

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Yeah, recording gear + gypsy electrical is a recipe for more kinds of disaster than just buzzing.

On the other hand, a carefully set-up system can provide for all your needs with both safety and capacity, even with existing wires. Mostly it's a matter of getting details right, not expensive gadgets.

First, a "tree" topology with several branches is a normal way to wire a circuit. When trimming back the excess electrical branches, no need to tear the wire out, you may regret it later. Just disconnect it inside the box, cap it off with a smallish wire nut, and wrap it with electrical tape so the cap doesn't fall off. Anyway, unused branches won't cause buzz.

Second, check out the grounding system. look for 2 features:

  • a ground wire run all the way back to the main panel, to protect you from electrical faults, and if your wiring doesn't have that, that's a problem but we can fix it definitively for about $200.
  • a grounding rod, to protect your gear from lightning, static electricity etc. It is optional if there's no breaker panel.

Safety Options

Now if your system is not grounded, the first safety feature you really will want is a GFCI protection device, and I want you to use a deadface unit. Why? It forces you to pause to understand how GFCI's actually work, which means you'll be able to protect the whole place with one of them ($25) instead of several.

A GFCI won't help with hum but it'll do worlds of good for safety.

The extreme option

I don't normally go to this option so quickly, but an isolation transformer was suggested, and why not go whole-hog and lick your grounding problem too, while also upgrading circuit capacity. Giving a modern, state of the art service.

Instead of a 120-120 isolation transformer, find a 240/480-120/240 supply transformer. A 5 KVA unit should suffice, and I see them used for $100. It takes power from the old supply cable, and isolates it, giving 120V or 120/240V at the shed. Since it's isolated, it doesn't need the ground wire from the house, just the grounding rod.

If your supply is 120V, you can feed that onto one 120V secondary and draw from the other 120V secondary. Or, you can change the supply to 240V and put that into the primary jumpered for 240V, and draw 120/240 split-phase off it at twice the power. (you could even punch it up to 480V with a second transformer, if you have a long distance to go.)

Double extreme

As ThreePhaseEel notes, the problem is often your own gear. But I'll discuss your old fluorescent lights and things like that. You can get a second supply transformer and use it to supply the non-music loads. This would put 4 windings between your lights and your music.

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  • Yeah -- the best way to wire that supply transformer is to use both 120V secondaries to feed separate legs in-phase, with separate neutral bars in the panelboard. Obviously, this means you can't have 240V or MWBC loads in the panel fed by this! Sep 28, 2017 at 11:46
  • @ThreePhaseEel I thought about using the dual secondaries, but I'm hoping to get more noise suppression out of two actual transformers. As far as 2 neutral bars, I'm reluctant to suggest that as it would violate the rule of "how this works needs to be fairly obvious to the next guy". Sep 28, 2017 at 15:56
  • 215.4(A) doesn't apply to 2-wire feeders, which means you can't have them share a double-size neutral, and you probably won't be into fat enough wire to use two parallel neutral wires instead of a double-sized one. Sep 28, 2017 at 22:15
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An outlet tester will let you know if the outlets are grounded and wired correctly and is much cheaper than Electrician. example of a tester. There are more expensive ones with a GFCI test buttons. Your power is probably coming from a breaker in your service panel or possibly a sub panel. Finding the breaker(s) you can see the rating it is usually stamped on the breaker handle. If the tester shows proper wiring you should be good to make noise.

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    Caveat: Those testers are good for detecting certain incorrect wiring but they can't detect, for example, a "bootleg ground" (where the ground pin is connected to the neutral instead of its own wire) or basically any cases of improper ground (unless of course they're downstream of a properly-wired GFCI).
    – gregmac
    Oct 28, 2016 at 20:36
  • thanks guys, so the next step if it is improperly grounded or pulling to much juice, how would i resolve that, Oct 29, 2016 at 12:08
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First DIY approach is to check if you have a problem. Set up the usual equipment in the studio, and turn it on - see if there is a ground hum or not. If there is, try to isolate which piece of equipment is causing it - and make sure it's not just an unused snake connection to the mixer which has been left unmuted (happens to me all the time...)

The first thing to NOT do when trying to fix a ground is to cut the power ground - that's completely unsafe. Using the built-in ground lift switch on a DI box or amp front control panel is safe - that doesn't break the power ground.

Haven't done so for years, but we used to use a 10/3 extension code with 4 x 110v sockets (two standard wall connectors in a metal box) patched in every 25ft. That would reduce us to one power supply, and stop ground loops caused by bad building infrastructure. Basically, we'd be bringing our own ring main with us.

If you can isolate the noise to one device, you can use one of these; enter image description here

To check for good ground, a GCFI connector as recommended by gregmac is essential.

To check how much power is being pulled by the building, install a home energy monitor - various types are available, going from a basic killawatt to more complicated versions with wireless, phone apps etc.

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The buzz is often the fault of your gear, not your wiring

There is an awful lot of audio gear out there that suffers from what's called a "pin 1 problem" where the shields of cables are connected to the internal signal ground instead of going directly to the chassis. This dumps the RF and 50/60Hz picked up by cable shields into the signal reference system as it's their only path to the chassis and AC mains earth at that point, where it can proceed to influence internal signals due to a gremlin called common impedance coupling -- in other words, if you have two different signal currents flowing through the same impedance (resistance), they'll influence each other somewhat at the other end even if you try to separate them out.

The solution to this is to either fix the pin 1 problems in your gear (which may or may not be possible) or to simply replace your gear with gear that doesn't have pin 1 problems.

Wire it correctly anyway (on both the power and audio sides!)

Note that fixing pin 1 problems doesn't give you an excuse to wire it wrong. "Bootleg" grounds or N/G reversals, looped or paralleled neutrals, or even looped/paralleled hots can cause excess powerline EMFs that contribute to noise currents. "Isolated" ground rods can inject transients into the system. The use of unshielded/untwisted cables for power and balanced interconnects, or the use of unbalanced interconnects that are coupled to earthed chassis, can lead to severe and hard to avoid noise problems.

In extreme cases, it is best to use a dual 120 output (i.e. a standard 240/480 -> 120/240 transformer with the secondaries wired in-phase but not in parallel) isolation transformer with an electrostatic shield as well as filtering coming into it. This should only be necessary if you're in a situation where you're trying to share a 3-wire feeder with a welding shop or something else equally troubling, though.

See this document for more details on most of this.

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