Can anyone help me with the electrical part of my UK plumbing homework please?

Question

I'm having trouble with 4 questions:

1 - When earth bonding to pipework, what does the label state?

2 - A branch from a ring final circuit is usually described as a...spur, socket outlet, residual current device or consumer unit. I'm thinking 'spur'?

3 - What is the fuse rating for a 9KW electric shower? I worked it out at 37.5amps but they only say 35 or 45 amps. I'm assuming 45.

4 - What is the main reason overload protection to an instantaneous shower has to be 30-40 amps? Exposure to water, KW rating, amperage, voltage rating? I'm thinking KW rating as watts/volts =amps.

Many thanks!!

Answer 1

I'll second all three answers ( or should that be triple ? )  

Answer 2

1.safety of electrical connection - do not remove

2. spur

3. 45 amps

4. KW rating

Answer 3

Lion of Judah has the answer spot on.

Answer 4

Yes the answers are correct

Answer 5

Agree with the above but Q4 could be amperage as overload protection is in amps. After all it is the fact that the electric showers draw so many amps that they need high overload protection. The amps is derived from the KW value on the basis that the voltage is nominally known.