20a DP switch for light

[Deleted member 26818]

Thought that when doing a MWC you were to test the circuit you have modified, not just your new bit.

Section 3 on the MWC is titled, INSPECTION AND TESTING OF THE MODIFIED CIRCUIT AND RELATED PARTS. to me this means all of it[FONT=Calibri, Arial, Helvetica, sans-serif]https://www.parcel2go.com/dhl-parce...ml_dhltrackingalert&type=email&location=email[/FONT]

It doesn't state such on the model forms in BS7671.
There are 4/5 essential tests listed that should be caried out, some of them will include the existing part of the circuit.
Such as earth continuity, IR and perhaps if applicable an RCD test.
Now if you want to check Zs, polarity correct etc. at each point on the circuit, please do so, just be aware that it is not a requirement of BS7671 to do so.

 

[Amp David]

Would never normally do Zs at every point anyhow. But would be doing all others, on the old and new part of the circuit.

 

[Short Circuit]

you will need to test the full circuit mate, and complete a minor works certificate

 

[Deleted member 26818]

Would never normally do Zs at every point anyhow. But would be doing all others, on the old and new part of the circuit.

So where would you do Zs at then?
What other tests would you do?

 

[Amp David]

So where would you do Zs at then?

Highest R1 R2 point

What other tests would you do?

Everything it asks for on the minor works.

I must be missing something here

 

[Deleted member 26818]

Yes you must be.
I asked you where you would test Zs, and you have stated at the highest R1+R2 point.
What about at the point where you have conducted the work? How would you determine where the highest R1+R2 point is?
The MWC asks for earth continuity, IR, Zs and polarity, but you have stated that you would not do Zs?
Make your mind up, either you would conduct a Zs test at each point or you wouldn't.
Recently I was asked to install a light in someones porch.
Simple matter as the CU was on the other side of the wall from where the light was to be positioned.
Run a feed from the downstairs lighting MCB to the fitting and then a switched line from there to the 2 gang light switch in the hall which was replaced with a 3 gang switch.
Should I then go to their downstairs bath room at the rear of the house, and drop out all the down lighters out of the newly decorated ceiling to establish which has the highest R1+R2 and then test the Zs?
How would that establish that the wiring I had installed had earth continuity, correct polarity and acceptable Zs?

 

[Amp David]

Never once stated I wouldn't do a Zs test.

With your litle porch light you'd of tested R1 R2, and proved polarity. Your Zs would be taken fronm furthest point on the circuit, might be the porch might not.