Correct cable?

frankxxxx

Fatherodonnell wrote: »

Ok thanks you are saying that a a regulation?
I don't get it though as it looks like 1 regulation says it's ok to protect a .75 flex with a 13amp fuse while another says it's not ok to use a .75 flex off a 10 amp fuse

fixed wiring minimum size is 1.5mm here..pretty sure it's in et101:2008 somewhere

0.75 flex connected to a portable appliance is different

2011

Fatherodonnell wrote: »

I am trying to understand what could go wrong with this set up and can't see anything.

I assume that you mean why can't a 0.75mm^2 flex be connected directly to a socket circuit?

In a domestic installation the cables that make up a socket circuit are generally 2.5 T & E and these are generally protected by a 20A type B MCB. This arrangement is inline with the rules, ET101:2008. As explained above the 20A MCB is unable to provide the 0.75mm^2 flex the protection that it requires to comply with these rules. One solution is to use a spur outlet in the manner described in my earlier posts.

Isn't the example of the German fridge more or less the same? A .75mm flex off a socket with no fuse to protect the flex apart from on the consumer unit?

The Germans have their own rules, they are not trying to comply with ours. Although the same laws of physics apply they same regulations don't.

Nothing bad can come back from the alarm panel because of the 1 amp fuse there?

What about local isolation?

What about the next person that replaces the alarm panel with a different fixed appliance that does not have an internal fuse?

Also even if I accept the need for 2.5mm cable

If you don't then why shouldn't we all wire circuits in undersized cables and save a fortune?

If nothing ever failed we wouldn't need fire alarm systems, fuses, MCBs, RCBOs, seat belts, airbags etc......

what do I need the fused spur for if I can easily isolate the alarm at the consumer unit?

In the real world this type of thinking causes accidents.
If local isolation is provided for a fixed appliance then a person working on it can isolate the unit and remove the cover knowing that the none of the internals are live. They could also do this at the distribution board, but there is a danger that someone will switch the power back on (yes this happens). There is also the danger that the wrong MCB is switched off (e.g. incorrectly marked). My advice is inline with best practice.

Local isolation points are important.
In Ireland local isolation is provided for the following fixed appliances:
Shower
Cooker
Boiler
Storage heater
Bathroom fan

All of the above could be isolated at the distribution board as well.
Why do you think local isolation is provided for the above?

The additional materials that are required to do it the way I have suggested would leave change from €5. Why on earth are you so determined to cut corners?
Assuming the electrical installation is wired properly (complies with ET101), why is there such a desire to make the installation noncompliant?

Fatherodonnell

Ok thanks for your response and I fully accept that the setup is non compliant, however I am not convinced that things are dangerous as they stand in this instance.
I take your point about local isolation but in this case the consumer unit is just above the alarm panel.
Because of the compliance issue I think I will follow your advice and get some 2.5 cable and a fused spur with a 3 amp fuse.
Thanks again