burglar alarm feed question

[tank]

i see. so there's no hard and fast rule that a FCU has to be fitted when the distance between the fixed equipment and the CCU is so small that the CB can reasonably be used as the local isolation. Some people would go 6 amp CB to 3 amp FCU to alarm. others would track down a 3 amp CB and go straight to the alarm.

would it be especially bad practice to go from a 6 amp CB straight to the alarm?

 

[Paul.M]

Let's not forget the basics regarding fuses.

The fuse/mcb is there to protect the cable. Most alarms are fed from a socket circuit. The alarm only needs 1mm cable so the mcb is over rated for the spur 1mm cable. In this case a fcu needs to be fitted to protect the 1mm cable therefore a 3A or 5A fuse to be used.

If your feeding it from the cu you can use a 3A or 6A mcb without the use of a fcu.

If the alarm panel was on its own dedicated circuit but no where near the cu I would always fit a fcu close to the panel for safe isolation for maintenance/repair.

 

[Paul.M]

^^^^ does that make sense or did I confuse things more?

 

[oldtimer]

An mcb can be used as a local isolation device long as its within "reasonable" distance and can be locked off. You can also use a mcb for functional switching.

In your case if the alarm is the only thing being fed from this circuit you don't need a fcu. Clearly mark the cu, alarm do not switch off. Please don't do what I've seen in domestic and commercial installs and put a bit of lecy tape over the mcb switch. Not good if it needs to trip!

Yep you can do this but sometimes an alarm is an afterthought and is doubled up with a lighting circuit ie 6 amps also does not help if the lighting circuits has a couple of strip or GU10 lamps on them.

 

[tank]

paul.m, you explain yourself fine. thanks for taking the time to help.

 

[Jay Sparks]

^^^^ does that make sense or did I confuse things more?

im dizzy..... "my head is spinning...."




Jay



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