R1 R2 on a 3phase circuit - what's the point in testing to each line conductor?

[Mizunoid]

If we are testing the continuity of the CPC, what's the point in testing between all three phases? Someone at work insisted upon it but i don't see the point.

Was told it was mandatory as there were three phases but we're only using the phase as a wander lead. I asked well what if we simply did a wander lead test and didn't use a phase and the guy said he didn't know.

From what i can see after thinking about it, if CPC continuity is why we're doing the test then why are we using three different 'wander leads'? Is it because the test is technically asking for the R1 as well and so all 3 phases need to be done?

Just a learner wanting to know.

 

[binky]

Sounds a bit pointless, but it does allow checking each phase conductor as well

 

[Fleeting]

R1 + R2 is part of your earth fault loop impedance so it would make sense to verify all three but you say you are only verifying R2?

 

[Mizunoid]

R1 + R2 is part of your earth fault loop impedance so it would make sense to verify all three but you say you are only verifying R2?

The point of the R1 R2 is to verify continuity of CPC no? What happens if you use a wander lead on the test instead of using a line as a lead?

 

[Fleeting]

The point of the R1 R2 is to verify continuity of CPC no? What happens if you use a wander lead on the test instead of using a line as a lead?

The point of verifying R2 is to prove continuity of the cpc. There is no specific requirement to verify R1 however is can be used as a method to verify R2, using R1 to verify R2 gives you R1 + R2 which is useful to verify the circuit complies with design parameters.

 

[Mizunoid]

The point of verifying R2 is to prove continuity of the cpc. There is no specific requirement to verify R1 however is can be used as a method to verify R2, using R1 to verify R2 gives you R1 + R2 which is useful to verify the circuit complies with design parameters.

Well yes but the question is, if we can test R2 with a wander lead then why do some people say we have to test R2 against L1 L2 and L3 on a 3 phase system? We're literally only using the line as a wander lead, so should be able to just use one of them to prove CPC continuity.

What's your opinion on this?

 

[SPECIAL LOCATION]

If we are testing the continuity of the CPC, what's the point in testing between all three phases? Someone at work insisted upon it but i don't see the point.

Was told it was mandatory as there were three phases but we're only using the phase as a wander lead. I asked well what if we simply did a wander lead test and didn't use a phase and the guy said he didn't know.

From what i can see after thinking about it, if CPC continuity is why we're doing the test then why are we using three different 'wander leads'? Is it because the test is technically asking for the R1 as well and so all 3 phases need to be done?

Just a learner wanting to know.

(1) Good question..

(2) Good to see that you can put forward a valid reason for your understanding. (rather than some lazy bods who just come on here expecting to be spoon fed answers..)

(3) The CPC (R2) question.. YES.. you are quite correct.. R2 is what you are needing to prove for BS7671 compliance. And as model forms in appendix 6 do say "R1+R2" OR "R2".. So if you can confirm R2 without the use of any R1.. then there is no need to bother about any of the three phase non-CPC and non Rn conductors.

(4) However.. it can also be useful to confirm that all conductors of a circuit are electrically sound along their length... So using the CPC as a ref for the Neutral, and/or L2,L3's isn't a bad thing to do anyway!!!

 

[Andy™]

r1r2 can also be used to verify polarity if you also include r1rn or r2rn. or in 3 phase, a various combinations. you also need to check phase sequence so it can also be used for that (not such an issue if its a coloured multicore, but some in trunking etc may be run in all brown and sleeved at the ends)

you could still do all that with a wander lead onto each individual conductor

really, its personal preference and whatever is going to be easier for te specific installation. might be r1r2, wander lead or a mix

 

[Fleeting]

r1r2 can also be used to verify polarity if you also include r1rn or r2rn. or in 3 phase, a various combinations. you also need to check phase sequence so it can also be used for that (not such an issue if its a coloured multicore, but some in trunking etc may be run in all brown and sleeved at the ends)

you could still do all that with a wander lead onto each individual conductor

really, its personal preference and whatever is going to be easier for te specific installation. might be r1r2, wander lead or a mix

You mean R1 and R2.

 

[newfutile]

If you do an R1+R2 test to each phase and earth you can add it to ZE and get your ZS which you need to test anyway , this also means you don’t have to do a live ZS