Max number of Watts on downstairs lighting circuit

[croz1977]

Sorry another post. I have a 5 amp downstair light circuit that is now loaded with the below:

12 x 60 w normal bulbs
23 x 50 w halogen

total watts = 1870

1870 / 230 = 8.13 Amps !

However Ive had all the lights on at once at so far, so good. Is this ok?

 

[bernardgreen]

Is this ok?

8 amps on a 5 amp circuit. No.... it is not OK and more importantly it might be creating a fire hazard.

The fuse or MCB will be getting hot as it is running at 60% over rating. if it is a MCB then the thermal trip mechanism will be heating up.

The fuse is there to prevent the cable over heating from excessive current.

If the cable's maximum safe current rating is 5 amps ( hence a 5 amp fuse ) then with 8 amps flowing it could be getting hot.

Many terminals on lighting circuits ( in ceiling roses etc ) are rated at 6 amps. In your system some of them are being over run by 50% These can get hot.

Not to mention the in-efficient lighting producing almost as much heat as a fan heater on the high setting. ( 2 Kw )

 

[croz1977]

OK Thanks,

So I need to rmeove some lights - What is the maximum Wattage I should have on this circuit? Ive tried looking it up and I cant find anything. Ive seen some guidlines that say you can go over the amperage on lighting circuits - I think this is called diversity and allows you to lower watt calculation by 33%?

Marc

 

[ricicle]

How is the switching set - up. Is there the likelyhood of all the lights being on at the same time ?

Can you change some of the halogens to 35W ?

 

[croz1977]

They will not be on the same time and yes i could easily switch to 35w bulbs

 

[ban-all-sheds]

Shame you didn't do the sums before you added those downlighters in the kitchen, wrecking your ceiling, ending up with lighting wholly unfit for purpose and almost certainly breaking the law in the process.

 

[croz1977]

Thanks for the usful comment - most of them where already fitted by previous owner you nobjockey.

Can anyone who knows what they are talking about tell me the maximum Wattage allowed on a 5 AMP lighting circuit?

 

[ban-all-sheds]

Thanks for the usful comment - most of them where already fitted by previous owner you nobjockey.

You had a circuit loaded with the below:

12 x 60 w normal bulbs
8 x 50 w halogen

total watts = 1120

1120 / 230 = 4.87 Amps

Have just installed 15 downlights (50w) in my kitchen.

You now have a circuit loaded with the below:

12 x 60 w normal bulbs
23 x 50 w halogen

total watts = 1870

1870 / 230 = 8.13 Amps

And BTW - I think you'll find that if you had 8 and you added 15, that most were installed by you, not the previous owner.

But call me all the names you like - it won't alter the fact that you've ****ed up the lighting in your kitchen, you've ****ed up the ceiling, you've almost certainly broken the law, and you're doing electrical work when you are nowhere near competent:

Can anyone who knows what they are talking about tell me the maximum Wattage allowed on a 5 AMP lighting circuit?

 

[Taylortwocities]

I know this is a DIY forum, so I'll not type what I was going to type.....

Here's your starter -

Converting Amps to Watts

The conversion of Amps to Watts at fixed voltage is governed by the equation Watts = Amps x Volts

For example 1 amp @ 230 volts = 230 watts

So for a 5amp supply your maximum will be 230 x 5 = 1150watts
About 23 lamps at 50watts.


Have you thought about low energy lamps? 11watts will give you the equivalent of 50watts of tungsten lighting.

 

[croz1977]

OK thanks - do the regs allow 100% of the total Amperage then. Also would be interested on your comments on the below from http://www.dusklights.co.uk/technical-advice/fitting-downlights.html which says 33% can be added due to diversity.

The calculation would be:

Total Watts ÷ Voltage = Amps

So taking the above information the calculation would be:

1200 watts ÷ 230 volts = 5.22 amps

So now we can see that the above described lighting circuit is using 5.22 amps meaning that the circuit breaker of 6 amps is not being overloaded.

Now to confuse things a little but very helpful on lighting circuits when you are wishing to add more lights. On lighting circuits once you have worked out the amps you can now apply a thing called Diversity, which for lighting circuits is 66% of the total load. So to work out this calculation we can do the following sum:

5.22amps ÷ 100 x 66 = 3.45 amps

 

[Paul_C]

On lighting circuits once you have worked out the amps you can now apply a thing called Diversity, which for lighting circuits is 66% of the total load.

The diversity figure is for determining the total load of the installation, allowing for diversity of load on all other circuits as well. The individual lighting circuit itself should be rated for the total connected load with all lights switched on.

 

[OwainDIYer]

Has the rule:

100 W per point or actual load if greater

been changed?

No diversity allowed on lighting circuits.

 

[JohnD]

what's your response on energy-saving lamps?

 

[Taylortwocities]

So now we can see that the above described lighting circuit is using 5.22 amps meaning that the circuit breaker of 6 amps is not being overloaded.

Now you are changing your goalposts. You said it was a 5 amp CPD

On lighting circuits once you have worked out the amps you can now apply a thing called Diversity, which for lighting circuits is 66% of the total load.

Diversity is a tool for experienced designers (which you, my friend are not).

The 66% GUIDE was written in the days when there was one 60watt lamp in each room and based on the fact that not all of the lights in a house/ on a circuit would be on at any one time.

If you have 300watts of downlights in one room, then they are all on or all off, so no diversity for you, matey.

 

[Paul_C]

The 66% GUIDE was written in the days when there was one 60watt lamp in each room and based on the fact that not all of the lights in a house/ on a circuit would be on at any one time.

It was still a diversity figure to be applied for calculating the total loading, not for an individual lighting circuit.