novice issue with a residential dimmer

[axiomflash]

hey all, writing from america here.

i have been doing a bit of electrical work around the home and today installed a dimmer switch. it isnt working quite properly though and im afraid ill burn the building down.

I am using a ceiling lamp with 4 small Halogen bulbs (G4 12V 20W).
The dimmer isn't grounded because I am in an old building and have nothing to ground it to. Hope this isn't a major issue.

So I installed the dimmer and the fixture works, but it reacts oddly to adjustments in the wheel. At full power it works great (though is moderately dimmer than when I was just using a switch). When I turn the know down it will turn off, then as I continue to turn it it will go back one at a lower brightness. The lower 2/3 of the wheel settings always leaves the lights off. What concerns me most is the dimmer buzzes when set to certain locations.

Could someone suggest what might be the issue? It could be the lamp, or maybe the old wiring, or lack of ground, or the wires on the dimmer are backwards? Too many options and I am pretty clueless.

Thanks!!!
____________________________________
Lynda, moderator

moved to electrics outside the UK

Please also note 6 & 7 here

 

[securespark]

You have posted in Electrics UK. Would repost in Outside UK, but I'll have a stab at it.

It sounds like the dimmer & fitting are mismatched, ie the load is not suited to the dimmer type.

Does the transformer in the fitting say "dimmable" on it?

Does the dimmer say "suitable for 12V" or similar on it?

As for the dimmer being grounded, I'm not sure what your local wiring codes are.

However, in the UK, we only have to earth (ground) Class I fittings ie those which are not double insulated (ie anything that has an earth terminal or earth wire attached to it needs grounding).

Does your dimmer have a ground terminal?

Lighting circuits in the UK are a big problem when they do not have earth wires, because many people attach metal fittings & switches to their wiring, and this is potentially dangerous.

 

[EddieCurrent]

Hello,

Do you know the 'range' of power the dimmer is designed for ?
You may be under the minimun load.

 

[securespark]

Er, that as well...

(I'll get you later, young Eddie...]

 

[axiomflash]

the light fixture i am using is: http://www.ikea.com/webapp/wcs/stor...-1&categoryId=16079&chosenPartNumber=10068971
unfortunately i dont have the packaging/direcions from it anymore. though it is from ikea so it would pretty much be pictographs anyways



And my dimmer is 120VAC / 600W max.
3-way push dimmer from GE



thanks for the quick repsonses, wow!

 

[securespark]

Thanks for that.

I can see from the website that the transformer is electronic - it may be dimmable, but without sight of the product, I can't say for sure.

You do not say whether the dimmer is suited to 12V loads - does it say on the rear of the switch? Or have you the instructions from the dimmer pack?

The rating seems well within, but, as Eddie pointed out, does the dimmer have a minimum load?

In the UK, most dimmers have their load types & ranges on the rear of the dimmer module.

As for grounding, the Ikea website says the GLIMT is grounded. Either it cannot go out ( ), or it needs connecting to ground.

I would say you need to reconsider fitting a light fixture that needs grounding to a supply with no ground. Is there a suitable fitting that does not need grounding?

You are at risk of electric shock should a fault condition develop at the moment.

Does that circuit have a GFCI?

 

[securespark]

http://www.ikea.com/webapp/wcs/stor...Id=10103&storeId=7&langId=-20&productId=47503

It would seem the model for the UK has a dimmer built-in. How strange!

 

[EddieCurrent]

Hello Secure,

'young Eddie' happens to be an his 40's sir...

Please keep 'posting' mate, you are a sound 'source of information' and I and I do thank all the 'regular' lads, who take their own time to help and advise us people learning, and others with their answers and opinions.

 

[axiomflash]

boy that is odd that the UK one has a dimmer built in. (my model doesnt have that black cord that is hanging there, but i figured that was an outdated model. mine actually runs the electricity through the solid metal cables that support the lamp. its pretty ingenious but i haven't figured out how it prevents one from shocking themself if they touched both cables at once)

the best info i can find on my dimmer is that it was made for GE by Leviton, and here is the product data sheet:
http://www.electricalreference.com/6683-A-itempik-245372.html
i haven't seen 'minimum load' an anywhere ive looked. sorry i cant figure that out.

Are you saying that my lamp poses a major risk since I don't have it grounded, because of the model that it is? I do recall it having that electric transformer in there now, didn't really occur to me.

Thanks again.

Keith

++++++++++++++++++++++++++++++++

"Does that circuit have a GFCI?"

Not sure what this is, I haven't seen this acronym anywhere I've been looking.

Do you think I would be best off (and safe) to just change back to a traditional (nongrounded) switch and use the lamp (which should be grounded, but isnt?)


Thanks guys, I think you are preventing me from burning myself to the ground

really.

 

[securespark]

To be safe, if you don't have any means of grounding available at the switch or fitting positions, you should not use "grounded" accessories, fittings, etc..

Maybe someone who is more familiar with US wiring codes could post here with more details?

The fitting prevents electric shock by running 12V through the cables , I presume. But nevertheless, if the fitting is grounded, as it says on the Ikea website, then it should be connected to ground. Otherwise, in the event of a fault, the metalwork of the fitting may become "hot". Without the ground wire connected to take the fault current away, the fitting will remain "hot".

Eddie: sorry, mate.

For some strange reason, I thought you was a whippersnapper...

 

[bernardgreen]

To be safe, if you don't have any means of grounding available at the switch or fitting positions, you should not use "grounded" accessories, fittings, etc..

Are the wires to the switch in a flexible metal tube that is fixed tightly to the metal box in the wall. If they are then it is very likely ( but not certain ) that the box is earthed. That dimmer is also available in a skeleton form ( no face plate ) which has grounding wires. This suggests the dimmer does need to be earthed.

(Securespark In some areas of the US all domestic cabling is in metal conduit, often corrogated flexible and this provides earthing. )

If the wires to the lamp are in metal tubing then that will provide an earth for the lamp.

The irregular control of dimming is an indication that the dimmer and the electronic transformer in the lamp are not compatible with each other. Nothing that can be done about that and use of a normal on-off switch is the only viable option.

Bernard
Sharnbrook
UK

 

[axiomflash]

sounds good. thats some interesting info about the conduit bernard. i see that metal conduit most places and always wondered why it wasnt just plastic.

this building however is 100 years old (really old for west coast of the usa ) and has knob and tube everywhere. most of the electrical plugs have been retrofitted so they are grounded, but i havnt been able to figure out what they are grounded to...