Trick Question

[flameport]

The ZS at the immersion was measured to be Twelve Ohms exactly.

With bonding connected or not?
If not, what was the Zs with bonding connected?
Is there any supplementary bonding installed?

 

[ericmark]

It is not an immediate danger so code 2. The 12 ohms is not a fail because it will not trip the protective device, it clearly will trip the RCD, but if 12 ohm then some where there has to be a bad connection. As to 1.5mm² on a B32 MCB well under 3 meters there is an argument but with 12 ohms clearly not under 3 meters so clearly code 2.

I feel giving code 1 where there is no immediate danger means people may not act when there is immediate danger. Where I see a problem with any EICR is what you do if you do have a real code 1? In the main we turn off the supply to test, that means we had to get permission to turn it off. Once turned off we can't turn it back on with a code 1, but also we can't leave a domestic premises in a state considered as unfit for human habitation. We need to ensure there is alternative accommodation for the occupants.

The Thirza Whittall case shows how to arrange for inspections or repairs is not good enough. If the premises is faulty then it needs you to arrange for alternative accommodation.

So question is code 2 acceptable as a reason to put the occupants into a hotel until repaired?

 

[bhm1712]

What would happen if the heater went short circuit?

 

[EFLImpudence]

What would happen if the heater went short circuit?

We don't know what the L-N loop impedance is.

For this seven metre, single load radial circuit with a Ze of 0.5Ω, it should be around 0.67Ω and perfectly satisfactory.
With a Ze of 0.5Ω, an L-N loop of 0.67Ω and Zs of 12Ω it is clear where the fault is/would be.

Is this the only circuit with such values - clearly CPC fault - or are all circuits the same - TNS earth connection or sheath failing, call DNO?
Edit - Ignore - forgetting Ze is reasonable.

I am still puzzled why the thread is titled "Trick Question".

 

[SimonH2]

What would happen if the heater went short circuit?

More to the point, what if the heater shorts part way along the element - thus (say) halving it's resistance ...

 

[EFLImpudence]

More to the point, what if the heater shorts part way along the element - thus (say) halving it's resistance ...

It would be its own fuse.



What about an answer or explanation from Kai as to why it is a trick question.

 

[SimonH2]

It would be its own fuse.

I read it as the B32 breaker being the only overcurrent protection.

There is NOT a 13amp fuse-connection unit inline.

EDIT: Ah, just twigged what you mean. I'm not sure the element would fuse, at least not in any way I'd want to rely on. It's not like a heater in free air that would get "quite hot" and probably melt quite quickly, this is in water which would (I suspect) be fairly effective at avoiding it overheating too quickly.

 

[Iggifer]

What about an answer or explanation from Kai as to why it is a trick question.

We won't get one. When he gets called out on being wrong, he no longer contributes to the thread.

 

[EFLImpudence]

EDIT: Ah, just twigged what you mean. I'm not sure the element would fuse, at least not in any way I'd want to rely on.

I'm sure it would be a common occurrence if that were the case.

If the element could withstand 26A, it wouldn't be very effective at its 13A design.
Plus it wouldn't be a solid connection at the break.