Purchased 12v 5a power supply for CCTV - what fuse

podgeandrodge

Hi, I purchased a 12v 5a power supply

https://www.amazon.co.uk/gp/product/B00C676JNM

for a 4 camera cctv system as the original power supply (rated same) failed, which had a 2 prong cable (not kettle) and a 3a fuse, but I can't be sure that this cable was the original that came with the cameras so perhaps the 3a was too small a fuse.

The new power supply doesn't come with the kettle lead - and I was wondering what fuse should be used with a kettle lead i.e. 13a or just 3a as I read that anything under 700w uses 3a. But if the power supply is 5a would that not blow the 3a fuse

Cerco

You should be fine with a 3A fuse in the plug. Don’t confuse the input current at 230volts with the output current at 12volts. They are related but dependent on the design of the power supply.

podgeandrodge

Thanks Cerco. I don't see many kettle leads online with 3a fuse - would 6a be ok? I presume 13a is not safe then as it would not blow?
I still can't figure out why a 3a fuse wouldn't blow if there is 5a output?!

LenWoods

there are C13 to Figure 8 Adaptors available online if that helps;
the only difference is the earth
link: https://www.amazon.co.uk/Almencla-Kettle-Female-Power-Adapter/dp/B07V6JRH4V/ref=sr_1_23?dchild=1&keywords=figure+8+to+c13&qid=1598803726&s=electronics&sr=1-23



C13 is king though,
ive fitted C13 cable to the rear of all my television wall installs,
i then have some C13 to Figure 8 Adaptors on standby, if the television takes a Figure 8 cable then i can easily adapt the C13 to suit,

Cerco

podgeandrodge wrote: »

Thanks Cerco. I don't see many kettle leads online with 3a fuse - would 6a be ok? I presume 13a is not safe then as it would not blow?
I still can't figure out why a 3a fuse wouldn't blow if there is 5a output?!

You use the standard 13A plug but replace the 13A fuse with a 3A bought separately. You can buy a pack of mixed fuses e.g. :

https://www.woodies.ie/catalogsearch/result/?q=Fuses

The input current is less than the output current.

alan4cult

podgeandrodge wrote: »

Thanks Cerco. I don't see many kettle leads online with 3a fuse - would 6a be ok? I presume 13a is not safe then as it would not blow?
I still can't figure out why a 3a fuse wouldn't blow if there is 5a output?!

The fuse is on the input side only. Also the 5A is DC and supplied at a lower voltage (12V). So as the previous poster said don't confuse input and output current.

coylemj

Cerco wrote: »

You use the standard 13A plug but replace the 13A fuse with a 3A bought separately. You can buy a pack of mixed fuses e.g. :

https://www.woodies.ie/catalogsearch/result/?q=Fuses

You'll get a lot more than four fuses on a card for €1.50 in the pound shops.

Ronin247

Watts is the measurement of power and is calculated by multiplying volts by amps.

The watts remain the same so a 60watt power supply with a 12v output is 60/12= 5amps output

The input is 240 volts but still supplies 60w so
60/240= 1/4 amp input so 3 amp fuse is more than enough.