High Zs value with 2 sockets

[TheCodboy]

Hi all, Doing some pre board change testing and ive found 2 sockets with high Zs readings. Everything else is fine, done all my end to ends and the Zs's are what should be expected. A couple of the sockets have Zs lower than expected but 2 are higher. They should be about 0.8 ohms but ive got one at 1.20 and one at 1.40. Taken the highest value socket off, re terminated, still high. Tested at the terminals of the socket just in case the socket was duff, but still high. Its a PME system with a good low ZE (0.15). Any thoughts people??

 

[TheCodboy]

Might just pretend i didn't see the high value socket...... (I'm joking!)

 

[Midwest]

As it's a bungalow, you'll probably be able to stand upright. It'll be just moving the odd upright piano, travel chest and rolls of old carpets.

 

[TheCodboy]

Im still scratching my head a bit as to why my r1 rn r2 values on the offending ring are as high as they are. The circuit cant be over 120m, so why so high?? ultimately if the Zs ok then its not a problem. Unfortunately my brain doesnt work like that and i always what to know why things are what they are!! Bit OCD!

 

[Ib≤In≤Iz]

I hope its not in the loft, its covered in insulation. Two layers, And there's hardly any space to move....

The story of my life.

 

[Ib≤In≤Iz]

Might be a junction box somewhere??

 

[ChrisElectrical88]

Im still scratching my head a bit as to why my r1 rn r2 values on the offending ring are as high as they are. The circuit cant be over 120m, so why so high?? ultimately if the Zs ok then its not a problem. Unfortunately my brain doesnt work like that and i always what to know why things are what they are!! Bit OCD!

Haha, you might get lucky and find 100m drum of 2.5 in the loft with the ends connected to make part of the ring main. Get digging!

On a serious note... are there any sheds or outbuilding you could have possibly missed where they have installed that as part of a ring main? I have seen that down before!

 

[TheCodboy]

Haha, you might get lucky and find 100m drum of 2.5 in the loft with the ends connected to make part of the ring main. Get digging!

On a serious note... are there any sheds or outbuilding you could have possibly missed where they have installed that as part of a ring main? I have seen that down before!

I was just thinking that.... half a reel in the loft! No,nothing outside. The customer has asked me to put some outside sockets in for him. Better put them on their own circuit or the end to ends will be off the map!!

 

[TheCodboy]

Might be a junction box somewhere??

Thats what i've been thinking. As its a total pain in the arse to find,that's probably what it is...

 

[TheCodboy]

Mystery solved. Took a few socket covers off and found lots of loose/poor earth connections and loose live connections also. Sorted these out and got much better Zs values and lower end to end values at the board. I carried out end to end tests at the problem socket (as a few of you guys recommended) and got readings of 0.03 for r1 and rn.

 

[Midwest]

Without going back to the beginning, that's sorted then?

 

[TheCodboy]

Without going back to the beginning, that's sorted then?

Yeah all sorted. Decent Zs now. 0.69 at the problem socket,0.4-0.5 around the rest. Get the board changed this week hopefully!!

 

[TheCodboy]

Appreciate all the help & input guys!!

 

[DPG]

Cool. Let us know how the board change goes!

 

[TheCodboy]

Cool. Let us know how the board change goes!

Board change all went well. Test results all good!!