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LV lights flickering

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360Youth

Senior Member
Location
Newport, NC
I recently installed 12v "hockey puck" lights with 20w lamps as undercabinet lights in a kitchen, switched by Lutron slide dimmers (toggle switch w/slide on the side). There are 8 fixtures on 3 switches. I was called back to troubleshoot the lights flickering. When I arrived, each zone could be turned on independantly with no problems, but as soon as a second zone is turned on, the lights to begin to flicker. I checked all my connections. Each receptacle that each WAC transformer (35w minimum/100w maximum output) is plugged into was fed independently (no shared neutrals, etc.) All equipment was customer supplied by the way. The dimmers are the kind with a tiny light built into the switch for "nighttime viewing" and I noticed that when I checked the recept. with switch off, ther is still 60v present. I finally decided to try with standard single-pole switch and all works fine. Job foreman opted to buy slide dimmers from local hardware store and we had same problem. The WAC transformer said on cover that they were "dimmable."

Is there a special dimmer required. I have never had problem before with different brand fixtures and transformers (although I can't atest to how many times dimmers have been used, but it hasn't been never).

Anyone had this before?
 

360Youth

Senior Member
Location
Newport, NC
Thanks. I just did a quick price check. WOW!!! I have a feeling the homeowners will become quickly content with single-poles.:grin:
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
mdshunk said:
You absolutely need a magnetic rated dimmer for this appilcation.
I have used the magnetic dimmers on electronic transformers and they do work however, the manufacturer says the dimmer wont last unless it is electronic, ie if the transformer is electronic. The Wac ones I used are.
Now check the price on electronic dimmers 360-- you'll go from wow to ow
 
Last edited:
360Youth said:
I recently installed 12v "hockey puck" lights with 20w lamps as undercabinet lights in a kitchen, switched by Lutron slide dimmers (toggle switch w/slide on the side). There are 8 fixtures on 3 switches. I was called back to troubleshoot the lights flickering. When I arrived, each zone could be turned on independantly with no problems, but as soon as a second zone is turned on, the lights to begin to flicker. I checked all my connections. Each receptacle that each WAC transformer (35w minimum/100w maximum output) is plugged into was fed independently (no shared neutrals, etc.) All equipment was customer supplied by the way. The dimmers are the kind with a tiny light built into the switch for "nighttime viewing" and I noticed that when I checked the recept. with switch off, ther is still 60v present. I finally decided to try with standard single-pole switch and all works fine. Job foreman opted to buy slide dimmers from local hardware store and we had same problem. The WAC transformer said on cover that they were "dimmable."

Is there a special dimmer required. I have never had problem before with different brand fixtures and transformers (although I can't atest to how many times dimmers have been used, but it hasn't been never).

Anyone had this before?

Are you dimming a receptacle? That would not be a permitted type of installation.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Pierre C Belarge said:
Are you dimming a receptacle? That would not be a permitted type of installation.
Pierre can you cite the article that states this. I don't dim receptacles because I am always afraid someone will plug a vacuum or something into it but if the outlet were under a sink or crawl space I have no problem. Many UL approved transformers for outdoor lights are dimmable and come with cord and plug. I'd love to know the article-- thanks
 

iwire

Moderator
Staff member
Location
Massachusetts
2005 404.14(E)


In short you can only dim permanently installed incandescent fixtures unless the dimmer is listed for other loads.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
iwire said:
2005 404.14(E)


In short you can only dim permanently installed incandescent fixtures unless the dimmer is listed for other loads.
How does that negate dimming a receptacle. A magnetic or electronic dimmer is listed for other than incandescent.
 

iwire

Moderator
Staff member
Location
Massachusetts
Dennis Alwon said:
How does that negate dimming a receptacle. A magnetic or electronic dimmer is listed for other than incandescent.

Yes but is not listed to supply any load through a receptacle.

It will be in the directions.

One of the device companies sells a dimmer unit with a special receptacle for dimming table lamps but you also have to change the plug on the lamp to fit.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
iwire said:
Yes but is not listed to supply any load through a receptacle.

It will be in the directions.

One of the device companies sells a dimmer unit with a special receptacle for dimming table lamps but you also have to change the plug on the lamp to fit.
So how are you suppose to dim a UL listed transformer that is cord and plug. The instruction for the dimmers warn about dimming a receptacle for fear against other equpment being plugged into it and doing damage. I would never dim a standard wall outlet for that reason but a receptacle (single) in a crawl space for a Transformer I would not hesitate-- I would also label the receptacle on the plate as being dimmed.
 

iwire

Moderator
Staff member
Location
Massachusetts
Dennis Alwon said:
So how are you suppose to dim a UL listed transformer that is cord and plug.

Your not.

Is this really an issue that comes up?

Why would you want to do this?


I would never dim a standard wall outlet for that reason but a receptacle (single) in a crawl space for a Transformer I would not hesitate-- I would also label the receptacle on the plate as being dimmed.

That is an NEC violation regardless of the label or location.
 
Lutron makes a listed receptacle/cord connection for just the purpose you are talking about.

As Bob has mentioned, there are not exceptions to the fact that standard receptacles can be controlled by a dimmer. If the manufacturer's instructions tell one to do this, I would forward the info to UL and let them deal with the manufacturer.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
iwire said:
Is this really an issue that comes up?
Why would you want to do this? .
Absolutely, 2 years ago I wired a 4 million dollar renovation and spent over 20,000 dollars on outdoor lighting, manufacturers were Vista and Kim Lighting, all UL approved and the main had Lutron Homeworks switches almost everywhere. He wanted every light in and outside the house dimmed- closet and all. Rope lighting also comes cord and plug and people always want to dim them.



iwire said:
That is an NEC violation regardless of the label or location.
I understand it is NEC violation to dim the recep. but sometimes you have to use common sense and look at the intent. The purpose is to avoid damage to other equipment. I believe I can avoid that situation in most cases. Indoor low voltage transformers made by LBL do not come with cord and plug but the WP Transformers do and they are dimmable. Interestingly enough I have never been called on it. I guess I will have to try and avoid it now.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Pierre C Belarge said:
Lutron makes a listed receptacle/cord connection for just the purpose you are talking about.

Are you talking about a cord and plug for a lamp. That is not what I would be able to use for outdoor lights. If different can you direct me to it.
 
Dennis

Try their website for more info on the product. I know that they were working on the design so the product would be ready for the '02 code cycle. I would even venture to say they probably had something to do with the change. :wink:
 

360Youth

Senior Member
Location
Newport, NC
I guess from now on I will have to plan on hard wiring the transformers instead of cord-and-plug them. Never knew that one. Previous install have been under cabinet or in attic space, so I never had to worry about other equipment being plugged in, but hey, that is one of the reasons I started coming to this site. Hard wiring won't be any more difficult.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Pierre C Belarge said:
Dennis

Try their website for more info on the product. I know that they were working on the design so the product would be ready for the '02 code cycle. I would even venture to say they probably had something to do with the change. :wink:
Thanks Pierre or should I say Merci Beaucoup
DFDU-nickelplate.jpg


I guess you could cut the cord and put the plug for these receptacles on it. I would probably just order a transformer without the cord. I know LBL makes them.
360Youth said:
Hard wiring won't be any more difficult.
Don't bet on it. Some of those transformer for puck lights are not meant to be direct wired. I guess you could mount them in an enclosure of some sort.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Pierre C Belarge said:
Dennis
A lot of people think I am french (When I was in college, I told the girls I was french), but I am half German and half Italian.
Yeah but what half of you is Italian and what part german??? LOL
Ciao
 
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