G
Greg:
Following on from the thread on Two way and intermediate switching (and related conversations) I was wondering where the "recognition" of just one of the methods comes from how far it had spread.
I've assumed preference stems from osg 7.4.4 as followed by Figure 7.3.
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No reference is made to power circuits yet the figure, referring to just one lighting wiring method, is entitled "Circuit for reducing interference with induction loops". It kind of implies that other forms of circuit would cause interference. How?
The figure highlights the run of the three cores between the switches noting "cores grouped together". But clearly both methods can be either used with sheathed "grouped" cables or by runs of singles (which may not always be grouped along such close and parallel paths).
Its clear from this forum that both methods of wiring are used and yet I've been informed that if wiring was done by line into common / switch live out of common that other electricians won't recognise the method used and that work would need to be redone. Do you know people who think this way?
I'm also interested in the insulator colour coding used. The figure has the note "Black/grey switch wires to be identified in accordance with Table 11A"; osg Table 11A has the note: (a.c.) Power circuits include lighting circuits and its section on the topic a.c. power circuit indicates brown in L1 and black in L2.
So is it best to follow the coding of Table 11A osg (also Table 51 big book) or of figure 7.3 osg?
Looking at various forums its apparent that there's a wide range of practices out there. Unless there's anything else to consider, I'd tend to go with T11A.
It seems to make things simpler to leave grey in the common especially if there is some expectation to cntinue to use the wiring method of figure 7.3.
The line into common method typically uses its grey as either switch live or neutral (with function dependant on the location of load) just to prevent black from being used as neutral so as to avoid confusion with the old system. By keeping black in L2 in both systems, the colour codings of both would be kept in harmony together and with the three phase codings.
Or am I missing anything here?
I've assumed preference stems from osg 7.4.4 as followed by Figure 7.3.
No reference is made to power circuits yet the figure, referring to just one lighting wiring method, is entitled "Circuit for reducing interference with induction loops". It kind of implies that other forms of circuit would cause interference. How?
The figure highlights the run of the three cores between the switches noting "cores grouped together". But clearly both methods can be either used with sheathed "grouped" cables or by runs of singles (which may not always be grouped along such close and parallel paths).
Its clear from this forum that both methods of wiring are used and yet I've been informed that if wiring was done by line into common / switch live out of common that other electricians won't recognise the method used and that work would need to be redone. Do you know people who think this way?
I'm also interested in the insulator colour coding used. The figure has the note "Black/grey switch wires to be identified in accordance with Table 11A"; osg Table 11A has the note: (a.c.) Power circuits include lighting circuits and its section on the topic a.c. power circuit indicates brown in L1 and black in L2.
So is it best to follow the coding of Table 11A osg (also Table 51 big book) or of figure 7.3 osg?
Looking at various forums its apparent that there's a wide range of practices out there. Unless there's anything else to consider, I'd tend to go with T11A.
It seems to make things simpler to leave grey in the common especially if there is some expectation to cntinue to use the wiring method of figure 7.3.
The line into common method typically uses its grey as either switch live or neutral (with function dependant on the location of load) just to prevent black from being used as neutral so as to avoid confusion with the old system. By keeping black in L2 in both systems, the colour codings of both would be kept in harmony together and with the three phase codings.
Or am I missing anything here?
