Old house with 2 prong outlets ground hum

[t56tr]

My house has two prong outlets. From what I was told, they are not grounded (?). Some of my guitar amps hum etc. My chameleon labs 7602 has the same problem when using the DI. Its not really noticeable when you are playing etc but its still there a bit. All of my gear plugs into a rack rider and a monster cable power center/strip (hey it was a give away at a guitar center). Those plug into one outlet using one plug each. Without rewiring my whole house is there some way to ground the one outlet that I use? Even if it involves changing the one outlet to a three prong, and running a single ground wire to it? If so where would it get grounded to?

Any info would be appreciated.

[lane thaw]

Here read this:

Ground Loops, or 'Let Me Hum A Few Bars' [SMR]

[nosebleedaudio]

Get an electrician to install a new grounded outlet..

[numrologst]

you cant just ground one plug. You'll have to ground the whole system and get new plugs installed

[mwd]

Get some solid copper wire, a 3 prong outlet and a copper grounding rod from the hardware store. Pound the copper grounding rod into the ground outdoors, attach the wire to it and come thru the wall near an outlet.

Install the new 3 prong outlet, ground it to the copper wire you installed. Test it for ground and reverse polarity with a Radio Shack outlet tester.

Now gang all your soundgear off of this single outlet to achieve a single ground source.I grounded the single outlet and plugged in an industrial strength 1400 watt battery backup I got off of eBay.

From that went into 2 distribution switches out to multiple power strips.I mounted all my rackmount gear with nylon washers on front and back.

This unit powers a computer, TV, 2 monitors, 2 external hard drives, external soundcard, 2 mixers, synth, about 14 rack devices, powered studio monitors, a color printer, laser printer.

Obviously not all at once however I have had quite a chunk of gear on simultaneously with little load on the system.

Although I can watch the load I am applying directly on the battery backup.

Clean and stable voltage... dead silent and cheap.

I have battery backup in a failure and in an electrical storm 1 un-plug and I am disconnected from any lightning strike potential.

[numrologst]

Originally Posted by mwd

Get some solid copper wire, a 3 prong outlet and a copper grounding rod from the hardware store. Pound the copper grounding rod into the ground outdoors, attach the wire to it and come thru the wall near an outlet.

Install the new 3 prong outlet, ground it to the copper wire you installed. Test it for ground and reverse polarity with a Radio Shack outlet tester.

I haven't studies up on my electrical code, but I am pretty sure you can't do that

[PoorGlory]

Originally Posted by numrologst

I haven't studies up on my electrical code, but I am pretty sure you can't do that

No, you can't.

2 Prong outlets should be grounded. The box itself is metal and should be grounded. When you use those 3 to 2 prong "ground lift" adapters, you use the screw on the plate of the actual outlet to secure the adapter to the plate using the little tab on the adapter. The plate should be metal (obviously).

I'm not an electrician, so anyone who is, feel free to correct my methodology.

And you definitely do NOT want to run a guitar amp ungrounded. This could and has resulted in death.

[nosebleedaudio]

A separate and isolated ground DOES NOT accomplish anything and it's dangerous and against code.
It MUST be connected to the main AC ground for several reasons
Anyone that says otherwise is clueless...

[mwd]

Well I reckon' things have changed since 05' ?

2005 National Electrical Code® Section 250-146(d). Where required for the reduction of electrical noise (electromagnetic interference) on the grounding circuit, a receptacle in which the grounding terminal is purposely insulated from the receptacle mounting means shall be permitted.

[stuntbutt]

Originally Posted by mwd

Well I reckon' things have changed since 05' ?

2005 National Electrical Code® Section 250-146(d). Where required for the reduction of electrical noise (electromagnetic interference) on the grounding circuit, a receptacle in which the grounding terminal is purposely insulated from the receptacle mounting means shall be permitted.

I believe that is referring to a circuit that has a dedicated/isolated ground. That ground is still ultimately connected to the grounding bar at the main panel. If it weren't then it would be possible to be shocked silly and never trip the breaker.

[nosebleedaudio]

Originally Posted by stuntbutt

I believe that is referring to a circuit that has a dedicated/isolated ground. That ground is still ultimately connected to the grounding bar at the main panel. If it weren't then it would be possible to be shocked silly and never trip the breaker.

Exactly, will not trip the breaker...

[nosebleedaudio]

Originally Posted by mwd

Get some solid copper wire, a 3 prong outlet and a copper grounding rod from the hardware store. Pound the copper grounding rod into the ground outdoors, attach the wire to it and come thru the wall near an outlet.

Install the new 3 prong outlet, ground it to the copper wire you installed. Test it for ground and reverse polarity with a Radio Shack outlet tester.

Now gang all your soundgear off of this single outlet to achieve a single ground source.I grounded the single outlet and plugged in an industrial strength 1400 watt battery backup I got off of eBay.

From that went into 2 distribution switches out to multiple power strips.I mounted all my rackmount gear with nylon washers on front and back.

This unit powers a computer, TV, 2 monitors, 2 external hard drives, external soundcard, 2 mixers, synth, about 14 rack devices, powered studio monitors, a color printer, laser printer.

Obviously not all at once however I have had quite a chunk of gear on simultaneously with little load on the system.

Although I can watch the load I am applying directly on the battery backup.

Clean and stable voltage... dead silent and cheap.

I have battery backup in a failure and in an electrical storm 1 un-plug and I am disconnected from any lightning strike potential.

Try this; check for stray AC voltage between your audio ground (chassis ground)and a known ground from your panel, you might find you have a potential between them, this is what IM referring to with regards to an isolated ground that's NOT connected or bonded to the AC ground.

[mwd]

Could be guys. I know I'm not Ready Kilowatt.

I didn't say anything about ground lifting or 3 prong adaptors. I recommended choosing an outlet, replace the receptacle with a 3 prong outlet. Ground the green screw and test it.

By all means rewiring your house for several grand would be choice one. And choice two would be get an electrician over while fully acknowledging that electricity can be very dangerous.

But I can promise you if you can't do any of the above then sitting there plugging gear into multiple open ground outlets with the possibilities of reverse polarity receptacles is far more dangerous than what I implied.

~~~~~~~~~~
the remainder of the code paragraph for possible clarification:
The receptacle grounding terminal shall be grounded by an insulated equipment grounding conductor run with the circuit conductors. This grounding conductor shall be permitted to pass through one or more panelboards without connection to the panelboard grounding terminal as permitted in Section 384-20, Exception so as to terminate within the same building or structure directly at an equipment grounding conductor terminal of the applicable derived system or service.

[nosebleedaudio]

Having a dedicated new circuit would be the best and least expensive, don't have to rewire the whole house...
Depends on where you are and if you have an inspector check it out.

[Sigma]

old home = radiators for heat..just connect copper wire to radiator

[mwd]

Let me reiterate something since we are talking about voltage and I don't want to see anyone get hurt.

My homemade grounded plug, right or wrong, does one thing which is charge the batteries in a power system that supplies my entire studio.
That's all it does. My studio literally runs off of batteries which accounts for much of the "quiet".

This battery system originally cost around 1800 bucks (though I paid far less) so it's not a cheap power strip. It constantly test and monitors for reversed polarity, low voltage, high voltage, no voltage on the fly.

It also reports any site wiring faults of which, according to it, I don't have.

Additionally all of my rack gear is plugged into individual NuMark Digital Power conditioners located in each rack case.

This scenario works well for me, is dead silent, non-shocking and test well.

Whether I'm lucky or living on the edge I can't say.

[stuntbutt]

It "works" because you haven't had a ground fault. Let's say that for some reason, a 120v lead inside a piece of gear came into contact with the metal chasis. In your setup, that metal housing is connected to your isolated grounding rod, but not to the grounding rod/nuetral bar at your main panel. Current is now passing through the metal case and flowing to your grounding rod. The breaker will not trip. It could be enough current to start a fire. If you happen to touch that piece of gear you could become the path for that current. Again, in that situation, the breaker will not trip.

EDIT Just realized that your battery system probably has fault protection. However the scenario I described would still apply to the UPS.