Typical domestic lighting cable circuits in 1973-74

[masser300s]

Hi All
hope someone can come to my aid. I have a 1973-74 built house with a large living area. I want to add 10 spotlamps around the room (its about 25ft x 23ft) with one central lighting point.

I've managed to find out that a lighting circuit must not be over 1200w (5-6Amp MCB) on the circuit for a 1.5mm2 cable. Does anyone know if the cable being used in the early to mid 70s was 1.5mm2 or larger or smaller?

The problem is that with current lights plus the spots, the total wattage becomes 1550W for that circuit. It will trip the 5A MCB. Do I just replace the MCB with a 10A (WYFLEX don't do anything in between 5 and 10A so it would have to be a 10A) or would I be doing something dangerous like overheating the wiring and creating a fire hazard?

Would really appreciate some feedback. Many thanks in advance.

 

[plugwash]

are there any markings on the cable?

does the cable run through any insulation?

does the cable have an earth?

 

[masser300s]

NO

NO

Yes

 

[plugwash]

does it have 3 strands in the live and neutral conductors? if so i'd guess its 3/0.29 which according to the table at http://electrical-contractor.net/PC/IEE1966_T3.jpg is ok up to 12 amp if theres no insulation so you should be ok with a 10A breaker.

one warning though if you have any SES or SBC lampholders on the circuit and you decide to uprate the breaker to 10A you should fuse them down (replacing the lightswitch with a FCU would seem an ok way of doing this)

 

[masser300s]

Yes indeed, just pulled down a ceiling rose and it does have 3 strands as you describe.

The current light fitting uses candle 60W bayonet bulbs and I'm proposing to use GU10 mains (not low voltage) spots.

Please pardon my ignorance but what is an FCU?

And many thanks for your help so far.

 

[masser300s]

I as thinking about replacing the light swith when having added the spots with a dimmer rated to be able to handle the wattage form the central light and the spots, would that be OK.