OK , I've got a home-owner installed Nutone intercom system . Every time he uses his intercom it has a loud BUzZ . One by one I shut down each station and come to find out that he has a station out by his built in BBQ in the backyard thats causing the buzz. After questioning him about how he ran the wires he confessed that he ran the LV wiring in the same conduit as the 110. So BINGO theres our BuzZ . Any ideas on how to help or fix this problem (running a new wire isn't an option). I was thinking of snapping on some ferrite cores on either end of the wire to reduce some of the noise .
Anyone ran in to this situation before .
Thanks
OnEcRzY

You might try some kind of notch filter. It is almost certainly a 60hz hum. Which one to use would be anyone's guess but mine. Try Nutone tech support for starters.

What your client did is outside of electrical code and a danger to users of the system, all the more so in that it runs outside and through the wet. (If you don't think any buried conduit of any type does not run the risk of getting wet or flooded by being outside, I invite you to think again.) Working on this exposes you to liability.

That being said, there may not be anything that can be done. What kind of wire did he run, sheilded or twisted pair? Or that intercom flat stuff?

The more I think about this, the less interesting it sounds. Any chance of walking away from this entirely? I would.....

I would RUN from this. I would type on your bill that there is a violation of code and a CERTAIN DANGER. If it were me I'd cut it and remove it. CYA!!!

Normally I would but this job was a favor . This guys a VP for a builder were tryin to land so I'm tryin to do whatever I can to keep him happy . How come the important jobs are alwayz the worst .

I would be honest with him, tell him the problem, and let him know that without re running new wires that you cannot in good faith get the system operational on a safe and up to code level w/o the new wiring, and if he still wants to persue "fixing" what he has screwed up, then I would say he would not be someone I would want to do work for on a professional level, I don't care how big his wig is, or how much money he has, he should respect your professional reccommendations for what they are. no new wire=run like hell.

This was the builder?

I wonder about other houses he builds too.

The others are right. safety aside, if he wants to get rid of the buzz, he has to get rid of the local induction. explore alternate routes for the intercom conductors (the 110 will want to stay where it is. It creates a sticky situation for the builder, and by pointing out the mistake to the owner, you might burn a bridge with the builder. Go to the builder first and tell him what's going on first if possible. If he's worth working with again he will do the right thing, and will remember that you gave him the opportunity to fix a mistake before making his life miserable with the owner.

Have to agree with those who say move the wire. Would also mention that ferrite chokes aren't likely to do you any good. They are mainly a high frequency product. At 60 Hz their inductance is so low it would take a ton of turns to do much good. If you could get enough inductance to reduce the hum, you would be reducing the audio level even more since the inductance will rise with increased frequencies.

I have forgotten which thread it was in but someone mentioned using them on power lines to try to control hum bars caused by a ground loop. The ferrite chokes that come with things like plasma sets, computer monitors and such aren't there for that purpose. They are there because the wiring radiates all the RF trash it picks up inside the monitor, causing the units to fail FCC specs on how much radiation a product can put out.

Warren ,
Thanks for the advice . It sounds like you've dealt with a few inductance problems in the past .
I looked for a wireless intercom that could communicate with this hard-wired system but according to Nutone technical support theres no such thing .
Sounds like I might have to fall back and punt on this one .

That's a typical builder for you...."go out of your way to fix my own stuff and maybe I'll send you some business"

It seems that with every passing year, I despise builders more and more.

yep, we gave up on builders for that very reason, we now work with architects instead, if its in the plans the builder is screwed, he has to have it done :) per the spec'd drawings. I enjoyed the day when one of the builders we have tried to work with found us working around him, it was a glorious day.

You are my hero.

I'm really too tired to play the old "kiss the builder's ass game" anymore. I've been down that road oh so many times.

Let there be no mistake that home builders are very aware and very exploitive (is that a word?) of the postion that they're in, and believe me, they intend to take full advantage of the situation.

builders suck