2391 Theory Test Paper

[Deleted member 26818]

In this respect, the Regulations are unusually quite precise.
Despite the fact that both socket-outlets and cables are parts that would go towards making up a circuit, there is no requirement in BS7671 for the whole circuit to be RCD protected when these parts require RCD protection.
The question is in relation to a circuit in an office, part of an installation where BS7671 would not normally expect ordinary persons to have access to any socket-outlets, and would expect the installation to be under the control of a skilled or instructed person, as such there would not normally be a requirement for RCD protection, unless a socket-outlet is used to power mobile equipment outdoors, and even then such would not require the whole circuit to be RCD protected.
The only references in BS7671 to circuits requiring RCD protection are in relation to special locations.
You would not normally expect there to be a bath or a shower in an office, so the only special locations that would be applicable to my mind would be those for agricultural/horticultural or transportable units.

 

[topquark]

Regulation 522.6.7 applies as a follow on from 522.6.6. A cable concealed in a wall or partition at a depth of less than 50 mm from a surface of the wall or partition.

 

[kennydeeee]

In this respect, the Regulations are unusually quite precise.
Despite the fact that both socket-outlets and cables are parts that would go towards making up a circuit, there is no requirement in BS7671 for the whole circuit to be RCD protected when these parts require RCD protection.
The question is in relation to a circuit in an office, part of an installation where BS7671 would not normally expect ordinary persons to have access to any socket-outlets, and would expect the installation to be under the control of a skilled or instructed person, as such there would not normally be a requirement for RCD protection, unless a socket-outlet is used to power mobile equipment outdoors, and even then such would not require the whole circuit to be RCD protected.
The only references in BS7671 to circuits requiring RCD protection are in relation to special locations.
You would not normally expect there to be a bath or a shower in an office, so the only special locations that would be applicable to my mind would be those for agricultural/horticultural or transportable units.

as i said cleaners sockets in an office for general purpose a cleaner would not be a skilled person the cleaner would be hovering after hours so would not be under any supervision from a skilled person so the sockets would would require additional protection.



I dont really care anymore i done this paper as a mock exam got this question marked right and got 90%

 

[Deleted member 26818]

as i said cleaners sockets in an office for general purpose a cleaner would not be a skilled person the cleaner would be hovering after hours so would not be under any supervision from a skilled person so the sockets would would require additional protection.

I dont really care anymore i done this paper as a mock exam got this question marked right and got 90%

There are exceptions for some of the Regulations requiring RCD protection in BS7671. Primarily these exceptions apply to commercial/industrial installations where the Electricity At Work Regulations apply.
Here is the entirity of Regulation 16 of EAWR 1989 "No person shall be engaged in any work activity where technical knowledge or experience is necessary to prevent danger or, where appropriate, injury, unless he possesses such knowledge or experience, or is under such degree of supervision as may be appropriate having regard to the nature of the work."
This Statutory requirement, entails that anyone (including cleaners) using a socket-outlet as part of their work duties must meet the criteria for a skilled or instructed person as defined in BS7671.
As such there is no requirement in BS7671 for cleaner sockets to be RCD protected, unless that socket-outlet is used for mobile equipment outdoors, or is in a special location
Now I don't know who marked your mock exam, or what answer you gave for this particular question.
I doubt though from the information you have supplied, that if you had taken the December 2010 exam, that you would have got this question marked as correct.

 

[Flakey]

Hi i was looking at this old post and saw a calculation resolved which im not too sure is right and would apprciate confirmation wether it is or isnt
Q24. A continuity of ring final circuit conductors test is to be carried out on a circuit supplying the office. The circuit is wired in 2.5mm cable with 1.5mm cpc. The loop length of the cable is 65m. All socket outlets are connected directly on the ring. Explain in detail, using the information given in figure 1, the three steps required to confirm the continuity of this circuit.
Your explanation should include the
. test instrument
. test connections and the expected readings at each stage
Show all calculations

A24. The test instrument used is a low resistance ohm meter. First test is an end to end of the line neutral and cpc of the ring. This is confirm all conductors form a complete ring. The expected results are:

Line – line – 2.5mm cable = 7.41 mohm/m
(7.41x65)/1000 = 0.48 ohms

Neutral – Neutral – Same as above

Cpc – Cpc – 1.5mm = 12.1 mohms/m
(12.1x65)/1000 = 0.786 ohms

Next cross connect line and neutral of the ring L1 + N2 and L2 +N1 and test at all socket outlets
Expected readings:

R1+Rn = (r1+rn)/4 = (0.48+0.48)/4 = (0.24) ohm Do you use this figure in the stage 3 part of the calculation

Next cross connect line and cpc L1 + cpc2 and L2 + cpc1 and test at all socket outlets
Expected readings:

R1+R2 = (r1+r2)/4 = (0.48+0.786)/4 = 0.32 ohms so 0.24 + 0.786/4 = 0.25 ohm ?

Many thanks
James