Max Wattage - Lighting Circuit

[dk1uk]

Hi - I want to add another strip light my garage, so I've totalled up the current circuit wattage and I'm worried...

I have the following wattage on one circuit breaker:

20 x 50w spots = 1000w
11 x 60w bulbs = 660w
Total = 1660w

I think it's a 6amp circuit - or at least I know that the circuit breaker is an MK 7932s B6 30mA - the one on the far left of the picture.

Have I got a problem? If yes, then is adding another circuit breaker to split the wattage easy enough (by someone qualified obviously - you can probably tell I'm not!).

Many thanks

Untitled

• dk1uk
• 21 Jun 2014
• 1

 

[bernardgreen]

6 amps and 230 volts is maximum of 1380 watts ( 1380 = 6 * 230 )

So if you have all you lights on then you are already overloading the circuit's protective device ( the MCB which appears to be an RCBO )

 

[dk1uk]

Thanks for the reply. Does the RCBO in the picture (far left) indicate that it is a 6amp circuit?

Thanks

 

[OwainDIYer]

Hi - I want to add another strip light my garage, so I've totalled up the current circuit wattage and I'm worried...

I have the following wattage on one circuit breaker:

20 x 50w spots = 1000w
11 x 60w bulbs = 660w
Total = 1660w

There's a rule/guideline of 100 watts per point or actual load if greater, so you should really have no more than 12 points on a 6A circuit.

Still, if you're happy with your ceiling heating installation ...

 

[AndyPRK]

It's unusual for all lights to be on the same circuit.

What does the b6 one next to it do ?

Adding a tube in the garage isn't really going to make any difference though.

 

[dk1uk]

That's not all the lights - that's just some of the downstairs and outdoor and porch lights (yes, lots of outdoor lights).

We never have all of those lights on at the same time, but still now that I know there's a potential fire hazard, I can't really ignore it.

Does that B6 one tell me for sure that it's a 6amp circuit?

 

[bernardgreen]

Does that B6 one tell me for sure that it's a 6amp circuit?

t tells you the device will trip when more than 6 amps flows through it for a length of time. The more the current exceeds 6 amps then the shorter the time

It says NOTHING about the circuit connected to it. One assumes that the circuit connected to it is safe at 6 amps but without examining the cable for size and installation method it has to be an assumption.

 

[dk1uk]

OK, thanks. The RCBO was installed/replaced by a Part P qualified electrician last year. This was when we had some work done to our kitchen and two lights installed outside the back door. I don't know exactly what work he did but I'm surprised that he wouldn't have sized up the circuit?

 

[EFLImpudence]

There's a rule/guideline of 100 watts per point

I don't think that will apply nowadays as, presumably, you cannot fit 100W per point.
66% anyway.
Surely just OSG verbiage for the hard of thinking.

or actual load if greater

Or less?

so you should really have no more than 12 points on a 6A circuit.

Eleven 3W LEDs would leave enough capacity for a tube.

Still, if you're happy with your ceiling heating installation ...

Quite.
However, I suppose there are garages and garages.

 

[AndyPRK]

is adding another circuit breaker to split the wattage easy enough (by someone qualified obviously - you can probably tell I'm not!).

Many thanks

Untitled

• dk1uk
• 21 Jun 2014
• 1

It's unlikely to be easy to add another MCB or rcbo to split the circuit.
It's difficult to tell from here!

What could be possible is to spur the outside lights off the socket circuit.
If you have problems with the rcbo tripping and have a lot of outside lights that could be one way to resolve it.


Although as someone said, money would be better spent converting some spots to LEDs !

 

[dk1uk]

Hmmm, maybe I should look at the LED option.

What would the safe load on a 6amp circuit be? 6 * 230v * 66% = 910w?

 

[dk1uk]

And in addition to my question above, before I go the expense of replacing the downlights:

- All of the downlights are the 12v low voltage type. I'm guessing not, but does this lower the 1660w calculation that I've made?

- Would I need to replace the 12v transformers for the downlights too or could I just replace the bulbs with LED MR16 bulbs?

Thanks again for the help.

 

[flameport]

- All of the downlights are the 12v low voltage type. I'm guessing not, but does this lower the 1660w calculation that I've made?

50 watts is still 50 watts - the voltage being 12v or 230v or any other voltage makes no difference.

Would I need to replace the 12v transformers for the downlights too or could I just replace the bulbs with LED MR16 bulbs?

12v LED lamps can be obtained - however they may not work properly with the existing transformers.
Replacement with 230v versions would be preferable, and as the lamps are the same physical size, it is usually possible to just remove the transformers and fit new lampholders without having to replace the whole fitting:
http://www.toolstation.com/shop/d220/sd3066/p34667

 

[ban-all-sheds]

What would the safe load on a 6amp circuit be?

6 amps.

All of the downlights are the 12v low voltage type.

//www.diynot.com/wiki/electrics:voltage-bands

 

[pjcomp]

Some years back a friend moved into a new-build which had been the estate show home. Hadn't been there long when she complained that she kept tripping out the lighting MCB. Turned out that because it was the show home the builders had loaded it up with downlighters - as she kept switching on the lights in different rooms the load went up until ... POP! This was before LEDs appeared, so the only thing she could do was make sure not all the rooms were lit at the same time (or remove some of the GU10s). I forget how many lamps were involved but it was a heck of a lot.

pj