Silly Electrical Mishap!

[ban-all-sheds]

I vacate this thread for a single day, and it explodes all over the issue of FCU's on a lighting circuit!

And who was the t**t who lit the fuse?

 

[eveares]

And who was the t**t who lit the fuse?

If your referring on whether it is OK or a good idea to have a FCU on a lighting circuit, I am not going to tie myself up in the argument.

 

[John D v2.0]

do you ... believe that it's a good idea to have a switch to isolate an alarm panel?

(yes, because although) you can isolate at the cu, but if they're on the lighting circuit that's not ideal.

But you will likley notice if your lighting circuit has no power and thus alert you to an issue.

Yes but i was talking about means of isolation not about which final circuit it was on. The issue i meant would be that you can't work on the alarm without isolating the lighting circuit, which if it's dark would not be ideal.

I think you may have missed the point; it is not about the alarm being silenced by switching the mains power off, but rather that one may isolate it accidentally with a normal switch and risk having the alarm go off when the backup battery gets low and eventually fail when the batteries fully drain.

Good point, you'd certainly want to label it well with "do not turn off".

 

[winston1]

Isolation can be required, the alternative could be darkness until an electrician can disconnect the faulty item to allow MCB and / or RCD to be reset.

Which a switch will do. If you are really worried about this unlikely sceneory don't put it on the lighting corcuit.

 

[winston1]

[QUOTE="eveares,


Lastly as quoted from the installation manual:


"Ensure that a readily accessible disconnect device Incorporated in the premises installation wiring shall be provided external to the equipment with a contact separation of at least 3,0mm and connected as closely as possible to the supply. "[/QUOTE]
A switch then or MCB.

 

[ericmark]

I have had three pole switches which come with a bracket and a lock so the supply can be isolated, however although using a switched FCU you can only lock off the line by putting lock in the fuse holder, even if some one does switch it back on, they have only switched on the neutral, in a British consumer unit it is rare to find double pole MCB's although you can get RCBO's which switch the neutral, but even then you don't really want to isolate the lights to work on an alarm panel so really pointless to consider that method.

However the selecting of a switched supply is more the point here, and that has always been a problem, not so much when it switches off automatically as in this case, but when it switches on automatically, and so one has to question "and connected as closely as possible to the supply." this seems to me wrong, the isolator needs to be clearly marked and if possible in sight of the item it supplies, does not really matter if an alarm or a boiler or any other item.

If we can't see the isolator, we can't see if anyone is fiddling with it, an alarm is battery backed, it does not stop the alarm working switching off the supply, so the isolator can be right next to the panel, testing for dead does not work when the supply is automatically switched, and I have myself made that error, lucky I as not working on it when it automatically switched on.

Even with a isolated and locked off supply, one can still get a shock, it also often needs a permit to work, the case in mind was the foreman sent two electricians to work on an installation and did not tell the electricians that there was another one working on it, a mega gives quite a nasty belt, even if it does not kill one, and the electrician using the mega could not understand the strange readings with the fault auto clearing itself. The foreman had to run and hide until they had calmed down a bit.

 

[securespark]

Is that Pyronix asking for a switched FCU on a BA panel??

 

[eveares]

The manual lists the supply via a diagram as the mains input terminals on the panel, however I agree it can read as if it is talking about the MCB.