2382 mock exam question help

[Penance]

Did a mock exam today and not too happy with answer to a question, well 2 actually. Ill give the questions and would appreciate people's ideas to answers as the lecturer didn't seem clear, infect he changed one of his answers to match my answer!

First one:
Which of the following earthing system would you expect to find connected to a caravan pitch
A: tncs
B: tt
C: tnc
D: tns

Second question:
Diagram showing a dp switch marked on/off supplying an immersion heater, question is - the intended purpose of the dp switch with on and off positions clearly marked is to provide
A: emergency switching
B: switching by skilled persons only
C: isolation and protection
D switching off for mechanical maintenance

What would your answers be?

 

[telectrix]

1st q. TT. 2nd, i would say C '

 

[Penance]

Exactly what I said but apparently I was wrong.

Question 1 he said tns which I disagree with but can't find a reg to say for sure.

Question 2 he said it was mechanical maintenance but I said isolation as 537.3.1.2 states that for mechanical maintenance the switch shall have suitable means of preventing unintentional reactivation and IMO a marked dp switch does not.

So who is right?

 

[white armour]

I would say that for Q2 D is the correct answer because for isolation you should have a means of locking off and that a DP switch does not offer any protection.

Regards wa

 

[Penance]

But the same applies to mechanical maintenance unless I am reading the regs wrong.

 

[telectrix]

it's a bad question anyway generally the D/P switch feediung an immersion heater is to turn the bugger on and off.

the 1st Q. can be TN-S or TT, but deffo not TNC-S

 

[Penance]

I agree, questions are too ambiguous.
The wording "expect to find" is really open to what personal experience has shown and yet c&g will only have one acceptable answer.
Yes a dp switch on an immersion was purely there for my dad to turn it off when we'd used too much hot water.