A quick one:help with dimmer switch for mains halogen lamps

[akbmcf1]

Hey peeps,

A real quick one that I just want to double-check with the general collective here on DIYnot!

We're expecting our first little bub in a few weeks so have been busy decorating the nursery and have bought a cute kiddy-style 3-lamp halogen light for his room. Max rating of the light fitting is 3x35W 240V GU10 lamps = total 105W.

Would like to fit a dimmer too so the missus doesn't have to blast the room with light when she is up in the middle of the night to feed him (hehe), so will this one do: http://www.screwfix.com/prods/47327...Switches-Sockets/Dimmers/Dimmer-1G-2W-40-250W? I've read about having to derate on dimming halogens, but this one says it doesn't have to be derated on tungsten (presumably meaning tungsten halogen?) lamps. By my reckoning, it would be fine even if derated (but that's why I wanted to check!!)

Thanks in advance for your help
Andrew

 

[GaryMo]

Looks fine to me Andrew.

Good luck with your little one.

 

[333rocky333]

Worth trying to get a rotary on/off one.

With the push on/ off most of the time you push it, it is too bright and you need to turn it down.
unless you faff about turning it down before pushing it.

 

[akbmcf1]

Worth trying to get a rotary on/off one.

Do you mean like this: http://cpc.farnell.com/pro-elec/6sdrw21/rotary-dimmer-40-250w-white-1-gang/dp/PL09945?

 

[333rocky333]

Yes thats rotary.
Not essential , personal choice really, your decision.

Not that it matters in your case, rotary are always 1 way and push type usually 2 way but can still be used as in your case as 1 way.

The one you show says, ways" two", contacts "two" ,so I assume thats a misprint

Proberly cheaper in B and Q

 

[ban-all-sheds]

That's a push on/off one - it must be if it's 2-way.

I thought the advice to get a rotary one was to guarantee that the light would always start dim?

 

[333rocky333]

That's a push on/off one - it must be if it's 2-way.

How can you tell that it is 2 way, it says rotary and also that it has two contacts.
Do not know why it says, ways two.

I thought the advice to get a rotary one was to guarantee that the light would always start dim?

That was the idea

 

[ban-all-sheds]

How can you tell that it is 2 way,

I can't begin to imagine....

it says rotary and also that it has two contacts.

L1 & L2?

Do not know why it says, ways two.

Maybe because it's 2-way?

 

[GaryMo]

That's a push on/off one - it must be if it's 2-way.

Why must it be a push on/off one if it's 2 way?

 

[johnnykc]

That's a push on/off one - it must be if it's 2-way.

Why must it be a push on/off one if it's 2 way?[/quote


If you think about a 2 way circuit, how could a rotary dimmer ever work unless it was left on all the time?

 

[ban-all-sheds]

Because as well as a rotating control to do dimming you need a single-pole changeover too.

If all you have is a knob which is off at it's anticlockwise extreme, and then as you rotate it clockwise you go to "ON @ 0" through to "ON @ 100%" you don't have a changeover.

You could make a push on-off one that was 1-way, but you couldn't make a 2-way that was not push on-off (except with a centre-off potentiometer).

 

[GaryMo]

I see your point

 

[333rocky333]

What would be the difference then, between there "Push" version and there "Rotary" ones

http://cpc.farnell.com/jsp/level5/module.jsp?moduleId=cpc/462272.xml

 

[johnnykc]

What would be the difference then, between there "Push" version and there "Rotary" ones

http://cpc.farnell.com/jsp/level5/module.jsp?moduleId=cpc/462272.xml[/quote


Where it says 'available in push and rotary forms' .....read ' available in 1 or 2 way' ....