Immersion wiring and amp sizes

[Luke105]

set up for immersion goes like this for me....

Option 1) 16amp breaker > 2.5mm t&e to 20amp DP isolator > flex from this to immersion.

But how is this set up.....

Option 2). 16amp breaker > 2.5mm t&e to 13amp fcu > flex from this to immersion

Are both fine?

 

[telectrix]

FCU is a recipe for disaster. 20A D/P switch every time for me.

 

[Deleted member 9648]

FCU is fully loaded @230v. 20a DP every time.

 

[Luke105]

FCU is a recipe for disaster. 20A D/P switch every time for me.

What are the implications of this set up

16amp breaker > 2.5mm t&e straight to timer > flex from timer to immersion.
Is this posing a danger other than no local isolation?

 

[Strima]

If domestic no requirement for local isolation if on its own dedicated circuit.

 

[GeorgeCooke]

You could use 1.5mm t&e with a 16a breaker.

 

[Luke105]

You could use 1.5mm t&e with a 16a breaker.

It was more to do with amp switchgears and isolation rather than cable size

 

[Wilko]

Hi - Local 20A DP switch for immersion isolation is appropriate IMHO as work may be done in the vicinity by someone not familiar with boards etc. I use 2.5mm from the board as it has margin for installation Method 103 worst case.

 

[Luke105]

Hi - Local 20A DP switch for immersion isolation is appropriate IMHO as work may be done in the vicinity by someone not familiar with boards etc. I use 2.5mm from the board as it has margin for installation Method 103 worst case.

So, good practice but not required.

 

[mossep]

If domestic no requirement for local isolation if on its own dedicated circuit.

Not sure that is true, where did you hear that? Im happy to be proved wrong though...

 

[mossep]

Although a 13A FCU should be ok, in reality it will probably over heat and the fuse carrier fail over time due to the high load.

 

[richy3333]

What do the manufacturers instructions say? Or is this a theoretical question? Local DP switch for me also. If the voltage fluctuates that fcu will die. Seen it happen so many times. Also the local isolation helps Mr wet pants who’s either too stupid or too lazy to isolate elsewhere!

 

[Luke105]

What do the manufacturers instructions say? Or is this a theoretical question? Local DP switch for me also. If the voltage fluctuates that fcu will die. Seen it happen so many times. Also the local isolation helps Mr wet pants who’s either too stupid or too lazy to isolate elsewhere!

Would you agree no actual requirement for local isolation

 

[buzzlightyear]

looking over time the only one fsu that would not fail was the mk bakerlight. not the ones we put in now .

 

[davesparks]

Local isolation is safer for anyone else working on the immersion heater in the future and also makes it easier for testing in the future.

A local isolator which is effectively under the constant supervision of the person doing the work is a safe isolation which doesn't rely on them having a lock off kit which many domestic workpeople don't. Also most circuits are rcd protected these days so the local dp isolation prevents tripping the rcd when N and 3 touch whilst working on the immersion.

And for testing the DP isolation allows you to test a suspect immersion heater without having to disconnect the neutral somewhere.

 

[davesparks]

If domestic no requirement for local isolation if on its own dedicated circuit.

Is that new in the 18th? As far as I know the only regulation specific to domestic currently is the one about non combustible fuse boards.

 

[davesparks]

If domestic no requirement for local isolation if on its own dedicated circuit.

Is that new in the 18th? As far as I know the only regulation specific to domestic currently is the one about non combustible fuse boards.