polarity testing

[paulthemagpie]

hi guys,

when testing to confirm polarity of swa going from house to outbuilding.

a. why is it necessary

b. why is it carried out before the installation is energised

 

[paulthemagpie]

is it

a. the test ensures all fuses, signle pole switches and themo are connected in L only. although this doesnt apply to the swa. but it checks all three lines are correcftly identifiied throught the system

b. for safety reasons.

 

[Deleted member 9648]

Pretty much......but add to b. that you wouldnt want to energise an installation with incorrect polarity.....and regarding a. you are checking the polarity of the SWA according to the question,not the entire system.

 

[Barry Rathbone]

Correct sequence for safe domestic electrical testing ​
BEFORE CONNECTION OF THE SUPPLY​
1​	Continuity of protective conductors
2​	Main and supplementary bonding continuity
3​	Continuity of ring final circuit conductors
4​	Insulation resistance
5​	Site applied insulation
6​	Protection by separation
7​	Protection by barriers and enclosures
8​	Insulation of non-conducting floors and walls
9​	Polarity
10​	Earth electrode resistance if an earth electrode resistance tester is used
WITH THE SUPPLY CONNECTED​
11​	Earth electrode resistance if an earth-fault loop tester or the ammeter and voltmeter method are used
12​	Confirm correct polarity
13​	Earth-fault loop impedance/PFC/PSSC*
14​	Correct operation of residual current devices
15​	Correct operation of switches and isolators

 

[telectrix]

to put it simply, if you test it dead and the readings are good, there's less chance of it going bang when you switch on.

 

[Barry Rathbone]

Visually check all connections so you know all connections are in the correct terminals, and all connection are Identified.3 core swa correctly identifed (Brown Black Grey - Brown Blue Green/Yellow).

 

[SJD]

Umm, what about prospective fault current, seems to be missing from the above list (to be verified before switching any circuits on)?

 

[Barry Rathbone]

Umm, what about prospective fault current, seems to be missing from the above list (to be verified before switching any circuits on)?

My instruments display both so I guess it's classed as one...anyone?

But added, will be emailing the company to add it to their web site !! No Hope..

 

[topquark]

Umm, what about prospective fault current, seems to be missing from the above list (to be verified before switching any circuits on)?

Step 13 both PEFC/PSSC, to ensure that all your protective devices are suitably rated before energising.

Edit: PFC->PEFC.

 

[AndyL]

Correct sequence for safe domestic electrical testing ​
BEFORE CONNECTION OF THE SUPPLY​
1​	Continuity of protective conductors
2​	Main and supplementary bonding continuity
3​	Continuity of ring final circuit conductors
4​	Insulation resistance
5​	Site applied insulation
6​	Protection by separation
7​	Protection by barriers and enclosures
8​	Insulation of non-conducting floors and walls
9​	Polarity
10​	Earth electrode resistance if an earth electrode resistance tester is used
WITH THE SUPPLY CONNECTED​
11​	Earth electrode resistance if an earth-fault loop tester or the ammeter and voltmeter method are used
12​	Confirm correct polarity
13​	Earth-fault loop impedance/PFC/PSSC*
14​	Correct operation of residual current devices
15​	Correct operation of switches and isolators

Have never liked the phrase "with the supply connected", alot of people get this confused with turning on the main switch, whereas steps 11,12 and 13 should all be carried out with installation isolated

 

[Barry Rathbone]

Have never liked the phrase "with the supply connected", alot of people get this confused with turning on the main switch, whereas steps 11,12 and 13 should all be carried out with installation isolated

You mean circuit isolated surely, ergo mcb in CU, but then try doing a polarity check/eli/pfc/pssc with the power not energised?

Reading too deep into this its the methods to get the correct polarity, on 1 garage supply...not a full installation...

 

[SJD]

My understanding of the term PFC (prospective fault current) is that it is the higher of the PEFC and PSCC, so you normally just list "PFC" which is taken to mean you measure both PEFC and PSCC and record the highest. Alternatively you could list out "PEFC" and "PSCC" and still just record the highest. (For a single phase system, at least).

 

[topquark]

You mean circuit isolated surely, ergo mcb in CU, but then try doing a polarity check/eli/pfc/pssc with the power not energised?

Reading too deep into this its the methods to get the correct polarity, on 1 garage supply...not a full installation...

No, he does mean installation isolated, at this point. The supply should be connected to the CU, but the main CU switch should be in the off position.

 

[AndyL]

You mean circuit isolated surely, ergo mcb in CU, but then try doing a polarity check/eli/pfc/pssc with the power not energised?

Reading too deep into this its the methods to get the correct polarity, on 1 garage supply...not a full installation...

Before adding a circuit you should carry out a test on earth fault loop impedance (Ze), for which you should be disconnecting the earthing conductor so installation needs to be isolated