lights from a fused switch (moved from Information)

[RobertPW]

Hi all

I have run a wall light from the ring main via a 3amp fused switch in the past which I believe is compliant with regs.

My questions is, if I wanted to run 2 independent lights (one either side of my bed) can I spur off one socket to a fused switch and then run a separate cable to each of the 2 switches (if so, is a 3 amp fuse still sufficient)? Or should each light have its own fused switch?

...Or am I missing something? Taking a live feed from the lighting circuit is not really an option in this case.

Thanks in advance.

 

[Taylortwocities]

Yes that is fine. 3A for both lights will be plenty.
If you are burying the cables in the wall, make sure they are run in "safe zones" (see WIKI for info)

 

[RobertPW]

Thankyou, all cabling in a stud wall.
Thanks for your advice.

 

[M&E Electrical]

3A fuse should be fine. as mentioned above, make sure you stick to the safe zones. For future reference to work out what Amp fuse you need. simply divide your total wattage by the voltage.
Eg you have two 50 watt lamps and your voltage is 230 volts so 50 x 2 = 100.
100 / 230 = 0.43
Meaning your load on the circuit is 0.43 amps

 

[winston1]

3A fuse should be fine. as mentioned above, make sure you stick to the safe zones. For future reference to work out what Amp fuse you need. simply divide your total wattage by the voltage.
Eg you have two 50 watt lamps and your voltage is 230 volts so 50 x 2 = 100.
100 / 230 = 0.43
Meaning your load on the circuit is 0.43 amps

That does not take account of switch on surge which you get with filament lamps or power factor which will not be unity with other types.

Lighting is generally run off 5 amp fuses or 6 amp MCBs. 3 amp is OK but will often fail if a lamp goes.

 

[RobertPW]

Thanks for all your advice. Its my first post and I was worried the keyboard warriors would be out to get me. Thanks for the explanation M and E, it's always good to learn.

 

[M&E Electrical]

3A fuse should be fine. as mentioned above, make sure you stick to the safe zones. For future reference to work out what Amp fuse you need. simply divide your total wattage by the voltage.
Eg you have two 50 watt lamps and your voltage is 230 volts so 50 x 2 = 100.
100 / 230 = 0.43
Meaning your load on the circuit is 0.43 amps

That does not take account of switch on surge which you get with filament lamps or power factor which will not be unity with other types.

Lighting is generally run off 5 amp fuses or 6 amp MCBs. 3 amp is OK but will often fail if a lamp goes.

just trying to give simple advice to someone who is obviously not an electrician. I didn't want to confuse anyone with something they may not understand.

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[winston1]

3A fuse should be fine. as mentioned above, make sure you stick to the safe zones. For future reference to work out what Amp fuse you need. simply divide your total wattage by the voltage.
Eg you have two 50 watt lamps and your voltage is 230 volts so 50 x 2 = 100.
100 / 230 = 0.43
Meaning your load on the circuit is 0.43 amps

That does not take account of switch on surge which you get with filament lamps or power factor which will not be unity with other types.

Lighting is generally run off 5 amp fuses or 6 amp MCBs. 3 amp is OK but will often fail if a lamp goes.

just trying to give simple advice to someone who is obviously not an electrician. I didn't want to confuse anyone with something they may not understand.

Sadly your advice is misleading. Anyone fitting a 500 mA fuse (next size above 0.43 amp) for a 100 watt bulb would be confused when the switch on surge blew it every time.

 

[RF Lighting]

Winston its your advice which is yet again wrong.

A 3 amp fuse is ideal for the OPs installation.

Your nonsense about inrush current and failing lamps is a great example of a little knowledge being a dangerous thing.

Power factor correction on a filament lamp, a pure resistive load? Good grief. I've heard you spout some nonsense over the years but this just about takes the biscuit.

I've never in all my years seen inrush current or a failing lamp cause a BS1362 fuse to operate.

I guess that's the difference between having practical experience as opposed to just knowing a tiny bit of the theory.

PS, where can I buy these 500mA BS1362 fuses you reference in your post?

 

[RF Lighting]

just trying to give simple advice to someone who is obviously not an electrician. I didn't want to confuse anyone with something they may not understand.

Don't worry about it. The only person you've confused is Winston, but that doesn't take much. If you stick around you'll quickly learn to ignore any advice he tries to give as the majority of it is wrong.

 

[winston1]

Winston its your advice which is yet again wrong.

A 3 amp fuse is ideal for the OPs installation.

Your nonsense about inrush current and failing lamps is a great example of a little knowledge being a dangerous thing.

Power factor correction on a filament lamp, a pure resistive load? Good grief. I've heard you spout some nonsense over the years but this just about takes the biscuit.

I've never in all my years seen inrush current or a failing lamp cause a BS1362 fuse to operate.

I guess that's the difference between having practical experience as opposed to just knowing a tiny bit of the theory.

PS, where can I buy these 500mA BS1362 fuses you reference in your post?

Why O why don't you read my post properly?

This is what I said "That does not take account of switch on surge which you get with filament lamps or power factor which will not be unity with other types."

NB Power factor will not be unity with OTHER TYPES, i.e those that are NOT filament lamps.

Filament lamps DO have inrush current and I have often known failing filament lamps cause BS1362 3amp fuses to fail (but not 5 amp ones).
I never referred to 500mA BS1362 fuses in my post, only 500mA fuses i.e other types.

By the way I never spout nonsense. M&E Electrical's calculation of Amps=Watts/Volts is only correct for DC or AC with unity power factor loads. Modern lighting systems are rarely unity power factor. This would suggest M & E Electrical are the ones with limited knowledge not me.

 

[RF Lighting]

Who are you trying to kid? Most of your posts contain incorrect information, and some of them are down right ridiculous.

Today you even got congratulated on another thread by a couple of people for finally posting something accurate!

If 500mA BS1362 fuses don't exist (they don't) why on earth would you mention them in a thread about lighting fed from an FCU other than a failed attempt to try and appear like you actually have sufficient knowledge to dismiss a factually accurate post from M&E electrical.

 

[winston1]

Who are you trying to kid? Most of your posts contain incorrect information, and some of them are down right ridiculous.

Today you even got congratulated on another thread by a couple of people for finally posting something accurate!

If 500mA BS1362 fuses don't exist (they don't) why on earth would you mention them in a thread about lighting fed from an FCU other than a failed attempt to try and appear like you actually have sufficient knowledge to dismiss a factually accurate post from M&E electrical.

What posts contain factually incorrect information?

I mentioned 500mA fuses as an example that the simplified formula from M&E would not work.

M&Es post was not factually correct except for DC and resistive loads on AC. If you don't understand the concept of power factor so be it, bit please don't critisise those that do.

 

[securespark]

3 amp is OK but will often fail if a lamp goes.

As would a 5 or 6A.

 

[winston1]

3 amp is OK but will often fail if a lamp goes.

As would a 5 or 6A.

Not so often. I had a case of failing bulbs taking out the 3A fuse but not a 5A. I assumed the bulbs internal fuse was greater than 3A but less than 5A. Of cause one must not assume but that is what I found.