ground loop in the house?

[amplifiednation]

So the woman who we bought our place from had a basket making business in the basement. This has turned into my workshop and jam room. Its a pretty sweet spot with tons of benches, pegboard, and shelving.

She had someone come in and wire up a ton of outlets in the ceiling where she had florescents installed throught the entire workspace for better light. They are all in series and controlled by two switches.

So heres my issue. Obviously the lights cause hum in my amps...but im getting hum with the lights off too, even in solid state equipment and literally on every amp that comes through the shop. I think I have a ground loop in the wiring of the outlets in the ceiling. What do I do? Can I star ground my basement??

Im working to get incandescents but dont really want to spend the money until these lights burn out. Any thoughts on the loop or the dirty circuit?

[paulster]

Do you actually have a solid ground connection to your outlets? That's where I'd start.

No ground is going to give you hum.

[amplifiednation]

Do you actually have a solid ground connection to your outlets? That's where I'd start.

No ground is going to give you hum.

I guess that's a good place to start!

[M Fowler]

Now is the time to get busy with a dedicated filtered power strip for your amps then you don't have to remove all the existing lighting. Maybe one intended for computer use would work here.

Then get one of those simple plug in testers from the local hardware store and see if your home is wired properly.

Mark

[amplifiednation]

Now is the time to get busy with a dedicated filtered power strip for your amps then you don't have to remove all the existing lighting. Maybe one intended for computer use would work here.

Then get one of those simple plug in testers from the local hardware store and see if your home is wired properly.

Mark

I've got one of those big surge protectors to protect the TV...would that do the trick? I'm not sure why I'm protecting a TV that I could replace for $500.

I'm gonna give it a try. wouldn't the florescents still cause hum? i was just going to wire in some track lighting instead of hte florescents...just would rather be building amps.

[M Fowler]

Because my ceiling in my bench room is open I used clamp on small dome shop lights and bulbs. But yeah track lighting would work very well.

You need your home wiring to be clean as possible I found that out!

Mark

[amplifiednation]

Because my ceiling in my bench room is open I used clamp on small dome shop lights and bulbs. But yeah track lighting would work very well.

You need your home wiring to be clean as possible I found that out!

Mark

Stinking home wiring...the hum is noticeable in all my equipment and gets worse with guitar pickups. I couldn't even dream of playing a single coiled guitar down there. I guess the most alarming hum is through the PA since there's not really many ways for it to get in there i would think

this is what most of the basement looks like. i bet i can find some joker with a bunch of track lighting to trade me for 20 florescent fixtures. it's like a huge aquarium! GREAT for seeing stuff though.

[Aurora]

Hum chasing is no way an easy task
I doubt that any filters or surge protectors wil help you in this case.
Looking at that picture, I'd suggest that there's something seriously wrong with your wiring. Since I don't play much guitars myself, I cannot jugde what is normal or not for single coil pups, but if an average SS amp keeps humming in there and not otherwise, I'd have a close look at that wiring.....
Try to measure if there's any voltage between neutral and ground in them outlets....may be a good indication of some serious grounding problems.
Should be 0 volts, as they're supposed to be conected at your mains inlet fuse cab......

EDIT: A possible grounding fault elsewhere in the house, may also skew the neutral.... try to measure the neutral/ground voltage several places in the house, and switch out circuit by circuit to see if the problem dissapears in conjunction with any particular subcircuit....

[selloutrr]

even flourescent lights that are turned off can cause hum in the circuit. You could try removing them completely from the circuit and see if the hum goes away.

You can also try an isolation transformer.

The trick is to keep audio and lighting completely seperated.

Does it make a difference if you float your amps ground?

Do you have anything else on the same power i.e. dishwasher, microwave, compressor, sprinkler system... etc.

The rats nest of wire in the pic is cause for alarm I'd bring in a certified electrician and have him address / rewire just for piece of mind the last thing i'd want is a house wire I could prevent.

[amplifiednation]

Awesome. Thanks for the replys friends.

So I did some measuring and there is voltage present from neutral to ground throughout the house. I have readings from .4 volts up to 2 volts. Is that enough to cause concern?

House was built in 1985...so there should be grounds in the outlets, and I did some electrical work here last year and i know there is an earth wire to work with.

Downstairs is just a sh*t show of wires though. I think the previous owner had the local handiman come in and wire up those outlets. If one of us saw an amp that looked like that we would probably vomit in our mouths.

Maybe I'll have someone come in and take a look. It pains me to pay someone to do anything that

[paulster]

First thing, regardless of when and by whom it was wired, is to get a plug-in outlet tester and just make sure that you actually have hot and cold round the right way (it happens) and that you have a ground connection at all.

After that you can start looking more in-depth at potential issues like whether your cold wire is at ground potential and suchlike, but I'd really start with a baseline first.

the last thing i'd want is a house wire I could prevent.

Yep, nasty things those house wires!

And I do agree with you about the potential that mess holds.

[Aurora]

Been out for some hours...... one thing just came to mind....
one of those outlets, or even one or more of those lights may be wired wrong, but since they're all on plugs, a the easy check is to just unplug'em....
Fluorescent light are a common source for radio noise in HF / low VHF bands in my work environment, but even with single pole breakers, there should be no noise - and no hum - when switched off. That's what suggests to me there's something wrong with the wiring, either around the lights and outlets, or somewhere else in the house.
If unplugging all them lights removes the problem, the fault is likely in the basement wiring.... Does your amps keep humming when conected upstairs ?

BTW- do you use GFIs in regluar domestic witing over there..???

[M Fowler]

GFI in bathroom, kitchen and garage areas. I forget all the areas they are required to be used.

[amplifiednation]

Been out for some hours...... one thing just came to mind....
one of those outlets, or even one or more of those lights may be wired wrong, but since they're all on plugs, a the easy check is to just unplug'em....
Fluorescent light are a common source for radio noise in HF / low VHF bands in my work environment, but even with single pole breakers, there should be no noise - and no hum - when switched off. That's what suggests to me there's something wrong with the wiring, either around the lights and outlets, or somewhere else in the house.
If unplugging all them lights removes the problem, the fault is likely in the basement wiring.... Does your amps keep humming when conected upstairs ?

BTW- do you use GFIs in regluar domestic witing over there..???

Yes we use GFI's. I don't know a lot about them though. I know there is a string of them throughout the house and if one trips they all trip.

I unplugged the lights, didn't make a difference. The Hum goes away with no volume on the guitar, but stays strong with volume on the PA. I do have an LCD computer monitor in the room and I currently have the refrigerator on that circuit as well (ghetto, i know). There is something down there that is generating the hum because I can point the guitar in a direction and make it go away (or maybe cancel it somehow??)

So this would probably mean one of the outlets could be wrong? can i tell from measuring "hot" to ground?

I'll probably have an electrician come over.

Oh, Aurora I do like the idea of killing circuit breakers to see if i can isolate the hum. Great idea. I'll just have to wait till the wife isn't home. I don't think she'll dig that experiment.

[paulster]

So this would probably mean one of the outlets could be wrong? can i tell from measuring "hot" to ground?

Yes, you can if you're careful. You want to measure 0Vac between ground and cold, 120Vac between hot and cold, and 120Vac between hot and ground.

If you get any voltage between cold and ground then you might have a poor ground connection in your house that should be explored.

Best thing to start though is to pick up one of these:
[img:300:300]http://ecx.images-amazon.com/images/I/4 ... AA300_.jpg[/img]
from Lowes, Home Depot or somewhere similar and quickly test all your outlets for basic wiring faults.

Every guitar player should have one, especially when playing out.