High Zs

[mcgaw81]

hey Guys

One of my sparks was carrying out a periodic inspection today and found the house had high Zs on all circuits.

However.............. Ze was only 0.07ohms, and all r1+r2's were ok highest being the lights at 0.67ohms.

Why would I get Zs of over 4/5ohms on all my circuits.

I spoke to 2 or 3 sparks the day, and they say that it could be a problem within the CU and they would change it.

Any help would be grateful

Cheers

 

[NozSpark]

Could be a high resistance across the L contact (or at terminals) in the main switch???

Easiest way to check is to do a Ze (with all MCB's off & bonds connected) on both sides of the main switch

 

[mcgaw81]

thanks Noz, will get him to try that tomorrow

 

[NozSpark]

Or L busbar could be on the wrong side of the terminal clamp in the switch???

 

[wozz]

didnt someone on here say they were having problems with a certain brand of rcd/ rcbo that was adding resistance to the circuit?

 

[kme]

1st thing I thought of, Nozzy.

either that, or loose busbar connection to main switch / main switch fault.

I don`t see it being MCB related; as it is common over all circuits; for the same reason it isn`t the screws MCB to busbar.

Nothing else it really could be, Mac

KME

 

[mcgaw81]

Could be a high resistance across the L contact (or at terminals) in the main switch???Easiest way to check is to do a Ze (with all MCB's off & bonds connected) on both sides of the main switch

Got the electricain to do this today, got 0.07ohms and 0.08ohms....... :_|

 

[NozSpark]

Got the electricain to do this today, got 0.07ohms and 0.08ohms....... :_|

I didn't expect that:_| :_|

How about to the busbar???

 

[mcgaw81]

Busbar ok, no visable sign of anything...Got him to fully disconnect it and put it back in.

Me baffled!!!!! bad day explode

 

[NozSpark]

What make CU is it??

Does it have a removable link on the earth bar for easy Ze testing? could it be loose?

 

[ianmacd]

Was the Ze tested at the same time as the Zs as it could have 'increased' temporarily for some external reason and fixed again by the next test.