Hi everyone,
I had a circuit today wired with FP200 cable and feed a fire alarm panel. Cable is 1.5mm, it is buried in the wall and protected by 20A mcb. I think 20A mcb is ok but which table am I looking for in the regs?
Thanks Paul.

Manufacturers.

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http://www.niceic.biz

Have a look here at the bottom of the page.

Does your panel require 4.5kw?

thanks for your replies.
I did a pir today. I didn't check what kw the panel required. I try to find if 20A MCB is overated for 1.5mm or if its ok.It was a nice and neat installation without any defects.

When installing FP 1.5mm to a panel I usually use a 6A MCB, fused down to a red switched fused spur with a 3A 1362 fuse in. Most of them consume mere milliamps. I also tend to put in a DP keyswitch near the panel for tamperproof DP isolation.

It is a 3-core and instead of a fused spur there was a 2-pole isolator with key(similar with the emergency lights key test switch). I cound see this switch to survive if 20A pass through.

I would say it is over rated for the cable and probably the panel as well. can you not find out any data for the panel?

I can't imagine any fire alarm panel would need to be on a 20 amp supply, more like 6 amp I would think?

Dave.

It is hard to go back but i will try. It is an empty shop but is hard to get the keys. I am not familiar with fire alarm panels but I never see on before on 20A. If there is a need for 20A supply I was expected to wired with 2.5mm and a different type of isolator than the keyswitch which i dont think is rated up to 20A

I was hinting in my first reply that 20A wasn't required for a fire alarm panel. It is only a circuit board with something like 24 volts going to the out going circuits.

Get a grip chaps - clearly we have a situation where the MCB is not offering overload protection to the fixed panel load (internal panel fuses will deal with this).

So the MCB is simply providing earth fault and short circuit protection - it's extremely unlikley that the fault levels will such that a 1.5mm2 FP200 will be overwhelmed by the energy let through of a 20A MCB.

Essentially it's a safety circuit - you don't want your protection to be too close do you ?

Regards

OMS

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Failure is always an option

i suspect inside the panel immediately after the line connection you will have a fuse protecting the board as well anyway, but as OMS said, its a fixed load .

Gary

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Specialised Subject. The Bleedin Obvious. John Cleese

For reference, from Prysmian's data sheets the current carrying capacity of 1.5mm, 3c FP200, enclosed is 16.5A.

Thanks for your replies everyone