ECN Forum Forums General Topics of the Trade General Discussion Area EMI Filter

It isn't "homebrew", except for the enclosure.

The filter itself is a commercially available, UL/CSA recognized component intended for use on these voltages (120/240), and up to 30A current.

I fail to see any violation here, with the possible exception of wire bending space inside the enclosure.

No more objectionable than mounting a contactor or other properly rated device inside your own enclosure.

Exactly what NEC violation should an inspector red tag this for? Not understanding what something does or why it was installed is not sufficient reason for an inspector to issue a violation.


[This message has been edited by NJwirenut (edited 03-28-2006).]

I traced the wire today & it is for a computer outlet. The owner is a programmer, so I suspect he had it installed. As I mentioned previously, there is a cover for this box, I took it off for the picture. The only violation I noticed in the installation was the use of NM wiring not allowed here, and wrong color wire used.

Thanks to all for your input. Would this be considered an installation for power quality?

Dave

Yep.

If you plan on reinstalling this unit, I would suggest a somewhat larger box, as well as a ground wire run from the ground stud on the filter (between the 2 line terminals) to the ground bus in the panel.

Does the owner realize that this thing offers little to nothing in the way of transient voltage suppression? Maybe you should try to sell a "whole house" TVSS unit along with the service upgrade since the owner seems concerned about power quality...

[This message has been edited by NJwirenut (edited 03-28-2006).]

Thanks for the tip. I am installing a whole house surge suppressor with this upgrade.

Dave

What most people do not realize is the line filter on a switched mode power supply for a computer is there to protect the rest of the world from computer generated noise, not to protect the computer.
The same was true of all of that bonding you saw in the raised floor computer centers.
It was the computer that made all the ugly "noise" we were protecting against.

Yes, most likely the computer plugged into the output of this thing already incorporates a similar filter network in it's power supply input wiring.

And to touch on something mentioned earlier, if there is an X-10 or similar wireless control system in use, it will NOT function properly on that branch circuit. That filter will remove the control signals quite effectively.

I doubt that it really matters here, but I could see where this installation that Dave has encountered might actually result in increased radiation. If Dave was dealing with Romex and noise was coming out of the computer PS input, the wiring between the filter and the computer outlet might have better antenna characteristics with the filter on the far end.
Joe