best practice for computer dedicated outlets

DiegoJames · 02-09-2013, 04:43 PM

Hey:

I installed a mere four double receptacles, or outlets, on a 20 amp line dedicated to my office for the desk area, all computer related, printer, scanner, modem, etc., though it also runs two lights around the desk area.

I left a junction box in the basement on this line in case I wanted to add to it; but the point of this line was to have it dedicated to computer equipment to avoid "humming" or other feed back noises through the computer. I did this out of prudence not based necessarily on knowledge as to whether it was necessary.

So, now I want to add four more receptacles/outlets to the same line in two other rooms. Is my original idea a good one to avoid noise/feedback or should I go ahead and add the four receptacles as I would indeed like to do?

md2lgyk · 02-09-2013, 05:25 PM

I've plugged my computer into several different outlets throughout my house and there has never been any hum or interference. I'd be more concerned with having surge suppression to prevent equipment damage.

Is either of the other two rooms a bedroom? If so, your plan may not be code compliant. I'm pretty sure (though I'm not a pro so may be wrong) that a bedroom has to be on its own circuit that supplies nothing else. And may require AFCI protection depending on the code version you fall under.

DiegoJames · 02-09-2013, 06:26 PM

umm... Thanks for the input regarding code and line dedication to bedrooms. Re surge suppression, yeah, I have good quality surge suppression in between all the office equipment and the outlets.

teamo · 02-09-2013, 06:33 PM

I am not aware of any code requiring bedrooms to have dedicated circuits. The arc fault protection is not the same as surge protection. Arc faults (afci) protect against arcs which can cause fires. Depending on the adopted code in your area you may be required to use them. Arc fault requirements started out as code requirements in the bedroom only. The latest updated code requires them in most other circuits throughout the house but your local jurisdiction would have to adopt them for your area. Whether they are required or not it is a good idea to use them.

A Squared · 02-09-2013, 06:40 PM

Quote:

Originally Posted by DiegoJames

Hey:

I installed a mere four double receptacles, or outlets, on a 20 amp line dedicated to my office for the desk area, all computer related, printer, scanner, modem, etc., though it also runs two lights around the desk area.

I left a junction box in the basement on this line in case I wanted to add to it; but the point of this line was to have it dedicated to computer equipment to avoid "humming" or other feed back noises through the computer. I did this out of prudence not based necessarily on knowledge as to whether it was necessary.

So, now I want to add four more receptacles/outlets to the same line in two other rooms. Is my original idea a good one to avoid noise/feedback or should I go ahead and add the four receptacles as I would indeed like to do?

It's not clear to me what you're trying to accomplish here.
What "hum" are you concerned about? Where is it coming from? Why do you believe that one particular branch circuit would be immune from this?

DiegoJames · 02-09-2013, 06:49 PM

There is no "hum" currently. I once was in an apartment where the fan I was running in the bedroom caused an echo response in the computer with wavering across the screen. I merely thought that it was a good idea to keep all the computer equipment on one line that would have no other types of equipment running on it. But this precaution was not based, as I stated, upon a firm knowledge of how or why such echo or hum response would occur on the computer screen, but rather only in prudence or intuition formed by the experience with the fan in the previous apartment as described.

md2lgyk · 02-09-2013, 06:59 PM

Quote:

Originally Posted by DiegoJames

There is no "hum" currently. I once was in an apartment where the fan I was running in the bedroom caused an echo response in the computer with wavering across the screen.

Reminds me of a place where I used to work. It was a manufacturing facility, and the weld shop was on the other side of the wall from my office. My screen wiggled every time one of the welders struck an arc.

kevinb70 · 02-10-2013, 01:01 AM

these were CRT screens? that would be EM and RF radiation going thru the air. You won't get that same distortion on a LCD screen.

As far as audible hum, now THAT I have had on computer speakers. I get that usually from cheap speakers with the 2 prong ungrounded wall brick power supply, also lacking on choke coil and capacitor to clean up the DC)

I don't get audible hum EVER with my sub surround which has a 3 prong plug - so the internal power chassis is grounded - completely eliminates that 60hz AC hum.

I can turn up the sub 100% and not a spec of hum.... I get hum on the ungrounded cheap speakers up past 40% volume...

As an IT guy... I have resisted the urge to install a dedicated PC circuit simply because I don't need the extra power and don't have hum issues other than a set of speakers which would still hum even on a dedicated circuit.

JohnnyB60 · 02-10-2013, 01:20 AM

It’s not really necessary these days. Many years ago I used to install isolated computer circuits in bank and also once in a department store for their cash registers. It basically was a circuit with an isolated ground wire running from the receptacle all the way back to the main power box. It was totally separate from the regular ground that also had to be connected to all the metal boxes or conduit if there is any which would mean two separate ground wires. They are usually designated by a symbol or the receptacle was orange. That really is the way to eliminate noise and not a dedicated circuit by itself because it can still pick up noise unless its inside a metal conduit.