I recently installed 6 50W mains powered halagon recessed lights in my hall.
I was quite suprised when switching them on how bright they were. They make
my 15 20W ones in the kitchen look like candles. I thought I would put a
dimmer switch in and went up to B&Q. The switch has also the outside light
on it so I will need a double dimmer with the outside light set to max on
the dimmer. However every double switch I pick up has a sticker on the pack
stating that if I am using halogen lighting then the maximum load is 250W or
150W. Can I assume then that on the maximum setting that the halogen bulbs
can only receive 250W of power or will something happen in the dimmer to
stop it from overloading, or will the dimmer cook!.?

Thanks for your help.

Andrew



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In article , Andrew
Simpson writes
I recently installed 6 50W mains powered halagon recessed lights in my hall.
I was quite suprised when switching them on how bright they were. They make
my 15 20W ones in the kitchen look like candles. I thought I would put a
dimmer switch in and went up to B&Q. The switch has also the outside light
on it so I will need a double dimmer with the outside light set to max on
the dimmer. However every double switch I pick up has a sticker on the pack
stating that if I am using halogen lighting then the maximum load is 250W or
150W. Can I assume then that on the maximum setting that the halogen bulbs
can only receive 250W of power or will something happen in the dimmer to
stop it from overloading, or will the dimmer cook!.?

The dimmer will probably cook. (I'm not sure why they are derated for
mains halogens).

Go to an electrical wholesaler like City Electrical Factors or someone,
and tell them what you want to do, they will have something more
suitable than B&Q.
--
Tim Mitchell

The dimmer will probably cook. (I'm not sure why they are derated for
mains halogens).

Go to an electrical wholesaler like City Electrical Factors or someone,
and tell them what you want to do, they will have something more
suitable than B&Q.
--
Tim Mitchell

I've phoned City Electrical Factors and they only do one with a max of 250W
for halogen lighting. However, they do a 35W bulb so I will buy those to
replace the load and one of their dimmers.

Thanks for your help.

Andrew.



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In article ,
Andrew Simpson wrote:
However every double switch I pick up has a sticker on the pack stating
that if I am using halogen lighting then the maximum load is 250W or
150W. Can I assume then that on the maximum setting that the halogen
bulbs can only receive 250W of power or will something happen in the
dimmer to stop it from overloading, or will the dimmer cook!.?

I'm pretty certain a low voltage model doesn't have to be de-rated for
mains halogens - it's the low cold resistance of the filaments that's the
'trouble' and something designed for an inductive load should also be ok
here.

TLC do a range of low voltage 2 gang 300 watt dimmers. They also sell a
switch only to replace one of the dimmers on that plate (for your outside
light) so you'd have a spare dimmer unit. ;-)

www.tlc-direct.co.uk

--
*I don't have a license to kill, but I do have a learner's permit.

Dave Plowman London SW 12
RIP Acorn

In article , Andrew
Simpson writes
I recently installed 6 50W mains powered halagon recessed lights in my hall.
I was quite suprised when switching them on how bright they were. They make
my 15 20W ones in the kitchen look like candles.

Mains halogens have larger filaments which means the light can't
be so accurately controlled. They are therefore spilling more
over a wider area, so you see more light. It is likely that the
20W ones are narrower beam and light their target better, but
don't spill light anywhere else. If the beam target is not
particularly reflective, the effective lighting of the room would
not be good. The 20W ones will be a good deal more efficient, so
the total light output will not be as big as a 20:50 ratio. You might
just be seeing a good demo of why such lighting is rarely effective
as general room lighting (my hall is lit quite brightly with around
25W consumption, whereas yours is consuming 300W).

In article ,
Tim Mitchell writes:
The dimmer will probably cook. (I'm not sure why they are derated for
mains halogens).

Two things I can think of -- halogens tend to have higher inrush
currents, and they often have no space for a fuselink in the lamp.
The former issue can be avoided by using a dimmer which can only
come on gradually.

--
Andrew Gabriel

"Andrew Simpson" wrote in
message ...
I recently installed 6 50W mains powered halagon recessed lights in my
hall.
I was quite suprised when switching them on how bright they were. They
make
my 15 20W ones in the kitchen look like candles. I thought I would put a
dimmer switch in and went up to B&Q. The switch has also the outside
light
on it so I will need a double dimmer with the outside light set to max on
the dimmer. However every double switch I pick up has a sticker on the
pack
stating that if I am using halogen lighting then the maximum load is 250W
or
150W. Can I assume then that on the maximum setting that the halogen
bulbs
can only receive 250W of power or will something happen in the dimmer to
stop it from overloading, or will the dimmer cook!.?


Yes, why do some dimmers have to be derated for mains halogen lights?? I can
appreciate there is more of a surge when firing up the halogens as opposed
to normal say 60w light bulbs, but the running load is the same.

??

Tim..


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In article ,
Tim.. wrote:
Yes, why do some dimmers have to be derated for mains halogen lights?? I
can appreciate there is more of a surge when firing up the halogens as
opposed to normal say 60w light bulbs, but the running load is the same.

Pretty well all semiconductors are rated for their *peak* current handling
capacity. Exceed that for a fraction of a nanosecond and they blow - which
is why a wire fuse can't protect them.

Dimmers are built right down to a price, so the triac they use is rated
at the minimum possible.

If and when mains halogens become the norm, I'd guess we'll see dimmers
commonly rated for them. But then you'll be able to over-rate them for GLS
types. ;-)

--
*Not all men are annoying. Some are dead.

Dave Plowman London SW 12
RIP Acorn

TLC do a range of low voltage 2 gang 300 watt dimmers. They also sell a
switch only to replace one of the dimmers on that plate (for your outside
light) so you'd have a spare dimmer unit. ;-)

www.tlc-direct.co.uk

--
*I don't have a license to kill, but I do have a learner's permit.

Dave Plowman London SW 12
RIP Acorn

Thanks Dave I will take a look at TLC's site.

Andrew.



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"Andrew Simpson" wrote in
message ...
I recently installed 6 50W mains powered halagon recessed lights in my
hall.
I was quite suprised when switching them on how bright they were. They
make
my 15 20W ones in the kitchen look like candles. I thought I would put a
dimmer switch in and went up to B&Q. The switch has also the outside
light
on it so I will need a double dimmer with the outside light set to max on
the dimmer. However every double switch I pick up has a sticker on the
pack
stating that if I am using halogen lighting then the maximum load is 250W
or
150W. Can I assume then that on the maximum setting that the halogen
bulbs
can only receive 250W of power or will something happen in the dimmer to
stop it from overloading, or will the dimmer cook!.?



If it quotes 250W that is the maximum power rating before it will blow, you
can run higher and take a chance - but you can't complain if it fails.

QH bulbs cause the derating due to high surge currents on switch on.

I have 1kW X.10 switch modules and they have to be derated to 500W on QH
floods .


Rick

On Fri, 31 Oct 2003 09:52:44 GMT, "Andrew Simpson"
wrote:

I recently installed 6 50W mains powered halagon recessed lights in my hall.
I was quite suprised when switching them on how bright they were.

I'd replace the bulbs with lower powered ones. It sounds like you
never want to adjust this dimmer, just use it permanently set at a
lower power. Halogens don't like this, and you'll get a greatly
reduced bulb life (depending on how low you have them). You may also
get the bulbs capsules blackening internally.

--
Die Gotterspammerung - Junkmail of the Gods

"Andy Dingley" wrote in message
...
On Fri, 31 Oct 2003 09:52:44 GMT, "Andrew Simpson"
wrote:

I recently installed 6 50W mains powered halagon recessed lights in my
hall.
I was quite suprised when switching them on how bright they were.

I'd replace the bulbs with lower powered ones. It sounds like you
never want to adjust this dimmer, just use it permanently set at a
lower power. Halogens don't like this, and you'll get a greatly
reduced bulb life (depending on how low you have them). You may also
get the bulbs capsules blackening internally.

--
Die Gotterspammerung - Junkmail of the Gods

Hi Andy,

Thats basically what I have done. I've reduced them to 35W bulbs and there
is a big difference and the sunglasses can stay off now.

Thanks everyone for your advice.

Andrew.



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In article ,
Andy Dingley wrote:
It sounds like you never want to adjust this dimmer, just use it
permanently set at a lower power. Halogens don't like this, and you'll
get a greatly reduced bulb life (depending on how low you have them).

I know this is the theory, but I've got three LV 50 watt above the
electronics bench which are on a dimmer, and spend a lot of time well
dimmed down. And have a longer life than the mains halogen in the
anglepoise which isn't dimmed and is on less.

--
*I started out with nothing, and I still have most of it.

Dave Plowman London SW 12
RIP Acorn

Tim Mitchell wrote:


The dimmer will probably cook. (I'm not sure why they are derated for
mains halogens).


Halogens run hotter, so when cold draw more current than a conventional
bulb.

Dimming means cold filaments and high peak currents, which heats up
dimmers more than running full crack.



Go to an electrical wholesaler like City Electrical Factors or someone,
and tell them what you want to do, they will have something more
suitable than B&Q.

Tim.. wrote:


Yes, why do some dimmers have to be derated for mains halogen lights?? I can
appreciate there is more of a surge when firing up the halogens as opposed
to normal say 60w light bulbs, but the running load is the same.


Not so at half brightness.