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OhNevermindMe 04-14-2010 03:40 PM

Can I ground an outlet via a cable jack?
Hi everyone,

I plugged a 3-to-2-prong adapter into the pictured outlet, and screwed in the ground tab like the instructions said, but when I plugged my surge protector/power strip into the adapter, its green "Ground" light wouldn't come on.

Turns out, none of the screws or exposed metal surfaces on the box containing the outlet are grounded. The nearest thing I could find that was grounded was the cable TV jack next to the outlet.

I'd really like to have a grounded outlet because I'm a recording artist and some of my equipment is hum-sensitive. Plus, I hear it's not safe to use a 3-to-2-prong adapter without grounding the ground tab.

So I'm thinking of just running a wire from the cable jack to the faceplate of the outlet (because if the faceplate is grounded, then the ground tab that's screwed into it will be grounded as well) -- but what I want to know is, would that be safe? Is there something horribly wrong with that idea? Would a thin wire containing only 7 strands of copper be appropriate for the job?

Thanks in advance.

Scuba_Dave 04-14-2010 03:51 PM

Bad idea
You need to run a ground back to the panel

Where are you located ?
Is this your house ?

AllanJ 04-14-2010 04:12 PM

You should bond the equipment to each other and to ground. Take a long #14 or so wire and screw it to each piece of equipment in turn so bare wire or the screw touches the chassis. Connect the far end to the known ground.

The cable jack shell could be a ground but it is not a good ground if the cable shield is foil as opposed to braided wire.

Yoyizit 04-14-2010 05:39 PM

The cable jack is probably not designed to withstand fault currents that can flow in grounds.

andrew79 04-14-2010 07:02 PM

like allanj said...if it's braided it would in theory work....i wouldn't try and watch t.v. though...or even have any of them hooked up.
legally though....never in a million years :)

i wonder what would happen to a plasma or lcd screen if a ground fault occurred.

Red Squirrel 04-14-2010 07:08 PM

I would do it properly and run a #12 or #14 to the panel. Since you are running wire, you may as well use #12 and make it a 20 amp circuit. Since the plug is not flush mounted, you could take the opportunity to do this as well. If the basement ceiling is unfinished or is drop ceiling this will be an easy job. If it's finished, then it may be impossible unless you want to break drywall and repatch.

ihildreth 04-14-2010 07:40 PM

DO NOT ground to your coax box. Yes it is grounded, and whoever installed it probably bonded the braid to ground in the house somewhere, but it is supposed to be the reference for the cable signal. Start putting junk on that and you no longer have a clean reference--probably TV problems. Plus that RG59 isn't meant to carry current like what you would find if there were to be a ground fault.

That being said. If there is no ground to your gear, there should be no hum. I'm an audio engineer at a large regional theatre, and when I run in to hum problems my first action is to flip the "ground lift" switch on the offending gear. Those 2-3 prong adapters are also used on equipment that doesn't have a ground lift switch.

Is anything rack mounted? I've got several huge racks filled with amps and EQs and such, all bonded together and with a single ground run back to the panel I pull my power from.

What kind of gear do you have? What kind of interconnects are you using? A lot of gear still has the "Pin 1 Problem" where the manufacturer decided it would be a good idea to connect the shield of the audio cable to the common trace of the circuit board instead of going straight to the chassis. It tends to induce hum and RF interference between equipment. I have a bunch of Whirlwind DI boxes that pick up the local AM radio station when they're hooked up to long cables because of this.

Let me know if I can be of any help.

goose134 04-15-2010 10:06 PM

Did you see if there was a ground wire inside of the box? Something tells me there probably isn't one, but it's worth a look. If it does, hook up three prong outlets and be done with it. If not, NEC allows for a ground wire to be run separately to the outlet (as long as it is not susceptible to damage). It is not commonly done, but is permissible.

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