Testing a Fused Spur

[markthespark]

Hello i am wondering if someone could help me out please.

I have been asked to installed a floodlight and my plan is to spur off the existing ring main to a FCU to feed the new light.

My question is what tests do i need to carry out?

Im a little unsure of whether i have to test the whole ring or whether i just test the new spur.

And also do i need to test the out going side of the FCU from the light and use the maximum Zs values for a 3 amp plug top fuse, or is this not necessary.
Many Thanks.

 

[telectrix]

Zs reading at your light fitting.. use the MCB for the circuit for max. Zs.

 

[markthespark]

Thanks Tel, im hoping to use this as one of my jobs for my NIC DI assessment.

On the MWC will it be ok to list the Zs and leave the R1+R2 and Insulation resistance parts blank?

Cheers.

 

[telectrix]

if this is for assessment, i would definitely measure the R1+R2 of the circuit, IR test that circuit, and finally the Zs. do the first 2 tests before connecting the floodlight.

 

[markthespark]

Thanks very much for clearing that up Tel.

 

[Farmelectrics]

as tel said if your getting assesed do the full tests r1 r2 ir and zs rcd

 

[telectrix]

sorry, i forgot RCD tests, my bad.:19:

 

[brman]

if this is for assessment, i would definitely measure the R1+R2 of the circuit, IR test that circuit, and finally the Zs. do the first 2 tests before connecting the floodlight.

meaning if it wasn't for the assessment then you wouldn't bother? tut tut..... :lol:

seriously though, does anyone bother measuring R1+R2 properly in this situation or just rely on the Zs? Excepting for assessments of course

EDIT: I just realised there is a reason I don't do a R1+R2, there is no space for the result on my MEIWC...........

 

[telectrix]

it's a debatable point. the whole purpose of dead testing is to ensure that the circuit is safe to energise. when modifying an existing circuit, it is already been energised. IR test to make sure that there has been no degeneration of insulation resistance, R1+R2, IMO is optional, unless there are signs of previous work giving rise to suspicion that all may not be kosher.

 

[Jay Sparks]

meaning if it wasn't for the assessment then you wouldn't bother? tut tut..... :lol:

seriously though, does anyone bother measuring R1+R2 properly in this situation or just rely on the Zs? Excepting for assessments of course

EDIT: I just realised there is a reason I don't do a R1+R2, there is no space for the result on my MEIWC...........

On the Elecsa MWC it just says tick one box (either R2 or R1 + R2) for continuity and give the Zs reading, so I just measure Zs which proves continuity.

Jay

 

[ackbarthestar]

As a first off DI assessment I think I would suggest that you did both dead tests (rfc 3 stages) and a Zs + RCD test. It wouldn't surprise me if the Assessor wanted to see you do the tests in front of him/her to confirm that you know what you are doing.

 

[Octopus]

Tin hat time!

Measure the Zs at the socket you're going to spur off, R1 + R2 for the new spur cable, IR new cable, connect up, Zs at end (compare reading to socket + new cable), RCD test at end.

heading down to the bunker!

 

[telectrix]

@ paul m, "last days of hitler". @ murdoch, OK IMO.

 

[markthespark]

Hi thanks for all the replies.

So ill be doing the steps 1,2,3 on the RFC and recording the R1+R2 value at the FCU as this will probably the highest reading as its a spur?

or record the R1+R2 for the RFC at the socket and record the R1+R2 of the spur cable separately?

Insulation Test on the whole circuit or Insulation on just the spur cable?

Zs at the security light.

RCD test.


Thanks

 

[Guest55]

Hi thanks for all the replies.

So ill be doing the steps 1,2,3 on the RFC and recording the R1+R2 value at the FCU as this will probably the highest reading as its a spur?

Probably , unless there are other spurs on the circuit further away from the CU than the one youre fitting.



or record the R1+R2 for the RFC at the socket and record the R1+R2 of the spur cable separately?

R1+R2 is done only once , at the furthest point , which will be at the end of your spur.



Insulation Test on the whole circuit or Insulation on just the spur cable?

Doing things by the book , ins res entire ring circuit , but can cause probs like finding hidden accessories , disconnecting appliances ....ect
I'd just ins res test the cables i install to be honest.


Zs at the security light.

Yes

RCD test.

Yes


Thanks

Regards pete.