Lights will be the end of me.

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We are in the middle of revamping the lighting throughout the house, and have decided to go into recessed halogen spots for the first time. Having no previous experience with them has already led to several scratched plans and re-thinks, but the latest one has me in need of advice on the following points:

1) I have seen mentioned that the 12v Halogens cause dimmers to need to be undervalued for capacity sake. By how much? The most I'll be running off of one dimmer will be 5x50w (no decision on transformer yet), so what sort of dimmer should I be looking for? Also, what should I look for on a dimmer to ensure that it will support low voltage?

2) We were going to use mains voltage Halogen spots, for the simplicity sake, and it was only when I began to purchase the dimmers that I noticed that all of the dimmers or information I saw suggested that the dimmer's wattage should be double that of the lamps hooked up to it. So that my 5x50 spots would need a 500w dimmer. I have found people who can get these, but they suggest that the plates can't be low profile due to the size of the dimmer modules, and they won't do them in 2gang or higher, just singles.

3) I read somewhere a chart about cable size for LV needing to be larger in some instances (number of lamps on a transformer, size of trans, length away from trans). My question on this is if one of these charts dictates the use of a conductor that is larger, how am I going to actually wire a larger conductor into a small aperture fitting on a lamp or transformer? Maybe this is a rare thing? I was hoping to keep using the same 1.5 cable.

4) Is there anything wrong with sharing a 3 gang dimmer between low voltage and regular old mains wall lights?


Thanks to all. Sorry for the length of questions. If you can help in any way the wife will be happy. Need to get the dowmstairs lights done so we can get carpet in for the baby on the way.
 
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q1 is answered by q2

q3 1.5 will be fine

q4 not a problem , since you will be dimming the primary side (mains input) of the transformers
 
Pardon the ignorance, but in regards to Q1 and Q2, are you saying that the wattage of the dimmer switch should be doubled for both mains voltage halogen lights and 12volt halogens?

If so, this puts me back into the special order for a more robust dimmer.

Cheers
 
The current thinking in the dimmer world is that when using Mains Halogen lamps, dimmers should be de-rated to half their stated maximum (plus a bit). In other words a 400W dimmer should be fine for 250W Mains Halogen.

For Low Voltage, everything depends on the quality of the transformer. Poor quality transformers (most cheap ones on the market) are fine for dimming in small quantities, but any more than 5 causes a phenomonen known as capacitance ringing which can cause flickering and the dimmer to fail. With good quality transformers, this is no problem. Only yesterday, I tested 20 good transformers with one dimmer to give 1000W of lighting.

If you are unsure of the quality of the transformer rate as follows. maximum 5 transformers, use transformer rating, not lamp rating. i.e. 5 x 60VA transformers needs a 300W dimmer even if onlz using 50W lamps.
 
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Thanks to all for the advice.

I decided to go with the LV lights and have purchased a 300w dimmer for the 5x50w LV lights.

Cheers!
:D
 

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