Alarm and heating fused spurs

[westward10]

If they go to construction sites it is almost certainly going to be TT and hence the fire alarm should have double pole isolation.

 

[Adam_92]

Yeah we don’t really do construction sites, when we do they’re run off generators so pretty pointless on having a fire alarm systems in because they never leave the generators running all the time which also effects emergency lights.

 

[davesparks]

Thanks very much Pete and everyone else for your input much appreciated

Also got my info wrong at first post the unswitched spur was for a carbon monoxide tester which was fed by a type b 6A is obviously the 3A fuse
And the heating system fed by a type B 6A must be a 5A

Why do you say obviously a 3A and must be 5A?
I would say the carbon monoxide detector doesn't need any further ocpd than the 6A mcb, these are designed to be directly connected to lighting circuits.
As for the boiler the 5A fuse after a 6A mcb seems largely pointless to my mind.

 

[Adam_92]

If the heating circuit was fed by a type B mcb rated 16A would you bother changing the fuse to a 5A in the fused spur or leave it as 13A? Surely you would put it on a 6A type B? If that was the case?

 

[davesparks]

If the heating circuit was fed by a type B mcb rated 16A would you bother changing the fuse to a 5A in the fused spur or leave it as 13A?

I would fit whatever size fuse is most appropriate to the load, usually this is a 3A fuse.
What exactly is it that you want to know in this thread?

 

[Adam_92]

I’ve been told you have to select a fuse rating for a heating and hot water circuit on am2 exam but not working on heating or hotwater systems I don’t really know?

 

[Pete999]

If the heating circuit was fed by a type B mcb rated 16A would you bother changing the fuse to a 5A in the fused spur or leave it as 13A? Surely you would put it on a 6A type B? If that was the case?

Depends what else was on the 16 Amp Radial feeding the heating, the supply to the heating could be a leg off the Radial covered by 5 Amp fuse in the SFCU, Don't you think?

 

[Adam_92]

Everything is being fed via the switched fuse spur but my thought process is if it was below 6A you’d put it on a type B 6A?

 

[Pete999]

Everything is being fed via the switched fuse spur but my thought process is if it was below 6A you’d put it on a type B 6A?

What else is the radial feeding?

 

[Pete999]

Everything is being fed via the switched fuse spur but my thought process is if it was below 6A you’d put it on a type B 6A?

What do you mean by everything else is being fed via the SFSU, what else exactly? A single line diagram would clear up your description I'm sure.

 

[davesparks]

I’ve been told you have to select a fuse rating for a heating and hot water circuit on am2 exam but not working on heating or hotwater systems I don’t really know?

Everything is being fed via the switched fuse spur but my thought process is if it was below 6A you’d put it on a type B 6A?

On the AM2 you wire it exactly as per the specification they give, I wouldn't be surprised if this also tells you the size of fuse required.
The fuse shoukd be sized according to the load, so work out what the load is and select the most appropriate size of fuse.
As I mentioned earlier for domestic and small commercial heating systems a gas boiler woukd be a 3A fuse and an oil boiler a 5A fuse.

As for the 16A radial, this is the normal circuit to be installed as a dedicated small appliance supply. For a boiler supply you would put a 3A or 5A fuse in the sfcu as required, Yes you could install a 6A radial but this is unusual.

 

[Pete999]

On the AM2 you wire it exactly as per the specification they give, I wouldn't be surprised if this also tells you the size of fuse required.
The fuse shoukd be sized according to the load, so work out what the load is and select the most appropriate size of fuse.
As I mentioned earlier for domestic and small commercial heating systems a gas boiler woukd be a 3A fuse and an oil boiler a 5A fuse.

As for the 16A radial, this is the normal circuit to be installed as a dedicated small appliance supply. For a boiler supply you would put a 3A or 5A fuse in the sfcu as required, Yes you could install a 6A radial but this is unusual.

This AM2 seems a right bundle of laughs.

 

[Adam_92]

The mcb is a Type B16A to a switched fuse spur in 2.5mm singles and a 1.5mm cpc.

Then from the switched spur goes to a heating and hot water system with a solar panels on it aswell that’s all the spec they give no power ratings anything :/

 

[Nigel]

A fire alarm panel should not be supplied via a switched fused connection unit or an un-switched fused connection unit.

This is what you should be installing.

Also the power supply should be in fire proof cable.

 

[Adam_92]

Try and tell the am2 assessors that they want it done the way it says in the design spec..