Continuity And Zs Test On An Oven Circuit

[Wizbit]

Hi all..A question re testing a standard radial BUILT IN oven circuit for an EICR in terms of what's expected/best practice...

Assuming I can access the oven connector unit in a cupboard next to the oven as the final connection point.. its my understanding that to do both dead R1+R2 and a MEASURED live Zs, I can take both these readings at the connector unit and record these both..yes? (House is on a TT so I do insist on taking measured Zs throughout whatever the 'advice' may be from up top re working live!)

BUT...given that the R1+R2 test is actually all about proving CONTINUITY of the cpc, surely the tests I've mentioned don't actually prove this??!..

So..would it be advisable as well as the recorded tests above to just do a continuity test say between the metalwork of the oven at the cpc at the connector unit just to prove to myself as the tester that the earth IS then continuous?

Hope that all makes sense!..any thoughts gratefully received.

 

[ProDave]

In what way does measured R1+R2 not prove continuity of the CPC?

 

[Technician]

So...your idea is to do an (R1 + R2) test and an R2 test?

With the R2 test conducted to test exposed conductive

parts?

 

[Wizbit]

In what way does measured R1+R2 not prove continuity of the CPC?

Cause if on this oven circuit I'm taking the R1+R2 reading between the CU and the Connector Unit..i'm missing out the last part of the circuit..the cable from the CCU to the oven itself..which is usual is inaccesible. So I'm getting an R1+R2 and Zs to write on the form..no problem...but surely this isn't acutally testing whether the cpc between the oven and the CU is continuous if I 'missed out' the last part of the radial circuit.

Same would be true on a shower circuit..i've seen many a spark take their R1+R2 from the 45A DP switch rather than open up the shower itself..surely missing the point of a continuity test?...

So..given that I'm going to do all measured Zs for EFLI, should I just use the R2 wanderlead method for my continuity on all radial and lighting circuits?

So...your idea is to do an (R1 + R2) test and an R2 test?

With the R2 test conducted to test exposed conductive

parts?

See above..you're right..I guess the approach could be to just do R2 on it (and all other radials) to actually confirm continuity, then do the live Zs tests from the CCU which is the closest termination point i can access. Do you reckon?

 

[steptoe]

well, I dont know any sparks that test a shower at the pull sw,

as for other fixed accessories, I put in the box that 'all fixed accessories tested at point of final connection only'

its not down to me to start opening peoples ovens etc up,

next thing we will have to plug stuff in and R2 them as well.  :shakehead

 

[sparkytim]

Hi rather then getting " readings to put in boxes on the form" an EICR is a report on the condition of an installation.

Continuity of the CPC is an important safety issue so however you prove it is "good" either by an R2 test, RI+R2 Test OR by Zs thats whats important.

Zs readings on a TT installation are a bit of a nonsense to read and some would say not a good indicator of the actual CPC continuity.

 

[SPECIAL LOCATION]

Hi all..A question re testing a standard radial BUILT IN oven circuit for an EICR in terms of what's expected/best practice...

Assuming I can access the oven connector unit in a cupboard next to the oven as the final connection point.. its my understanding that to do both dead R1+R2 and a MEASURED live Zs, I can take both these readings at the connector unit and record these both..yes? (House is on a TT so I do insist on taking measured Zs throughout whatever the 'advice' may be from up top re working live!)

BUT...given that the R1+R2 test is actually all about proving CONTINUITY of the cpc, surely the tests I've mentioned don't actually prove this??!..

So..would it be advisable as well as the recorded tests above to just do a continuity test say between the metalwork of the oven at the cpc at the connector unit just to prove to myself as the tester that the earth IS then continuous?

Hope that all makes sense!..any thoughts gratefully received.

Well.....

If you have just installed the circuit you will be doing the R1+R2 on the cables before you or someone else  installs the oven....

BUT...

If you are doing a periodic inspection  (EICR) then you probably wont be doing any R1+R2......

that is if you are following the guidance of GN3 table 3.3...

as on an existing installation there can often be far to many parallel paths to make a R1+R2 a bit meaningless..

I think you question is answered quite clearly in Guidance Note 3!!

Guinness      

 

[Technician]

See above..you're right..I guess the approach could be to just do R2 on it (and all other radials) to actually confirm continuity, then do the live Zs tests from the CCU which is the closest termination point i can access. Do you reckon?

No;  Please be aware that I did not assert that a test for R2 only should be done.

R2 tests SUPPORT  (R1 + R2) tests, they do not replace them.

Apologies to the forum;  I am feeling that way out today.

 

[bulmer]

Is the OP concerning more that he wants to check the appliance is earthed, as in connected the the cooker connection point (usually behind the appliance) correctly here?