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Old September 20th, 2007, 10:36 AM   #1
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Location: Hampshire, UK
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Fuse rating question (UK)

I've just replaced the lamp and a blown fuse in the plug of an Ianiro Lilliput (650W) light.

The plug is rated 13amp but the fuse inside (that was in it when the kit was bought three years ago) is only 5amp.

I only had 13amp fuses to hand so that's what I used as my need for the light was urgent. Worked perfectly.

My question is why would the plug have only a 5amp fuse as supplied? Am I doing anything stupid by using a 13amp fuse and should I rush out and buy a pack of 5amps?

I'm afraid I am one of those people who uses high power equipment with impunity but cannot fathom out how it works! I do know that my aunt lives in West Virginia ;-)

Thanks.

Ian . . .
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Old September 20th, 2007, 02:48 PM   #2
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Your 650watt lamp on 240 volts draws a current of 2.7 Amps. It would be safer to use 5 Amp fuses on its plug.

The 13 Amp fuse will work, but will blow at a much higher current than your light normally uses.

People often ignore the fuse rating, but it's safer to use the correct fuse otherwise with some equipment there's risk of damage and perhaps a consequent fire hazard due to overheating.

Having said that with these lights the fuse usually tends to go if there's a short or, sometimes, if the bulb blows.

However, for the small cost it would be safer and best practise to use the correct fuse.
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Old September 20th, 2007, 03:38 PM   #3
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Perfect response, Brian, many thanks.

It explained what I needed to know, I understood it, and I know what to do now!

I'm glad I asked.

Cheers.

Ian . . .
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Old September 20th, 2007, 03:43 PM   #4
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Ian,

If you're intersted in some Ohms law (Basic Electronics)
P = I x V
Where
P = Power (Watts)
I = Current (Amps)
V = Volts

So:

in the UK your voltage is 220V
The power of your lights is 650W
therefore current requirement (or consumption) is:
I = P / V
I = 2.954 Amps

Now when filaments are cold they tend to suck a large amount of current for an instant. So a 5Amp fuse is perfect for this light.

Of course your electric meter turns one unit for every 1000W an hour. Roughly, (don't know the cost per unit in the UK, but you'r eletric bill will tell you - You do pay your bills don't you? Or is that also part of the services for you "special" folks?)

The CFL lights I bought will cost you 1/6 the 650W you have but will give you 900W of light that is cool. :)
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Old September 20th, 2007, 04:23 PM   #5
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Sadly I pay the bills! No such special service in that regard!

Actually we have 240v here but I understand the principal. (I learnt the 'my Aunt lives in West Virginia mnemonic A=W/V).

Doing a good sales job on the energy saving lamps there Shiv! I will explore further.

Cheers,

Ian . . .
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Old September 20th, 2007, 05:20 PM   #6
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Bummer I was working up to my 500th post!

I didn't get the "My Aunt lives...".

More the voltage less the current requirement/consumption (as you can glean from the formula). When I was back home in India we used 230V for calculation purposes since the voltage could vary between 220-240V.

CFL lights:
I spent over a week researching CFLs. In doing so, I read some interesting findings with regard to "full spectrum" lights as well. Since in order to be a good Photo/Video light the light must really be a full spectrum light. Also specified as CRI (Color Range Index). Essentially, a CRI of 100 is an incandecent bulb which is theory is supposed to contain an even distribution of the visible spectrum. This means all colors are visible equally. Which is what we need for our purpose.

A good CFL lamp (good meaning full spectrum; a CRI of 90 or more is good) also has health and productivity benefits. And yes, I'm a proponent for Green Earth and energy conservation!
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