Testing limitations

[vbyrne]

I cant do Ze because I can not turn off the power,it has to stay running 24/7, what do I do???

 

[Phil]

ze does not have to be measured put down the figure relevant for the earthing system

 

[Deleted member 9648]

Can you not test at the nearest place which can be accessed without shutting down and note this on the cert.....if that is a DB close or connected at the origin the difference will be neglegable.

 

[vbyrne]

ze does not have to be measured put down the figure relevant for the earthing system

would that be acceptable,what if the earth was not as good as it should be

 

[vbyrne]

Can you not test at the nearest place which can be accessed without shutting down and note this on the cert.....if that is a DB close or connected at the origin the difference will be neglegable.

I thought that the Ze on a circuit could only be measured at where the suppliers incomer ends and the consumers equipment starts

 

[Sparky Ninja]

It can be obtained by enquiry or measurement.

Sometimes ze cannot be measured as bonding conductors can't be removed etc. If I'm ever in this position iwill record the enquiry reading, and then measure a couple of local zs readings if possible just to assure myself.

 

[vbyrne]

It can be obtained by enquiry or measurement.

Sometimes ze cannot be measured as bonding conductors can't be removed etc. If I'm ever in this position iwill record the enquiry reading, and then measure a couple of local zs readings if possible just to assure myself.

There is only one Ze in an installation is that right, every thing after that is Zs

 

[Sintra]

would that be acceptable,what if the earth was not as good as it should be

Your line / earth impedance reading can only be lower testing it at any other point than origin due to the parallel paths of the main bonding.

I thought that the Ze on a circuit could only be measured at where the suppliers incomer ends and the consumers equipment starts

Correct Ze can only be measured at origin.

As a limitation though test at closest accessible point to origin with bonding still connected and note this figure as Zdb.

 

[vbyrne]

Your line / earth impedance reading can only be lower testing it at any other point than origin due to the parallel paths of the main bonding.



Correct Ze can only be measured at origin.

As a limitation though test at closest accessible point to origin with bonding still connected and note this figure as Zdb.

Thanks m8, after all the reading I've done on testing I've never came across that one, I'd just like to be sure if my boss put me over it.
By the way Im from Newry, I noticed that your from Belfast.

 

[Sparky Ninja]

There is only one Ze in an installation is that right, every thing after that is Zs

Correct


I said I then measure ZS at other points. Typically because if you have a circuit with an R1&R2 of say.. O.24, and you measure a zs of 0.84 on a TNC-S system then you would suspect the Ze to bearound the 0.6 area.. Which exceeds the maximum.



Ze measured downstream from the origin is considered Zdb, only measured downstream on the supply side of consumer units though.

 

[vbyrne]

Correct


I said I then measure ZS at other points. Typically because if you have a circuit with an R1&R2 of say.. O.24, and you measure a zs of 0.84 on a TNC-S system then you would suspect the Ze to bearound the 0.6 area.. Which exceeds the maximum.



Ze measured downstream from the origin is considered Zdb, only measured downstream on the supply side of consumer units though.

How is that calculated, or is there an equation for that

 

[Sintra]

Thanks m8, after all the reading I've done on testing I've never came across that one, I'd just like to be sure if my boss put me over it.
By the way Im from Newry, I noticed that your from Belfast.

Another one from Norn Iron then think there are a few more on here.

 

[vbyrne]

Alright guys, I have just been at a house to fit a 32amp pull cord, when I went to the consumer unit there was a 16mm earth coming from a cut out that was fed with just two tails ,this is a TT system ,so I did a Ze and got a reading of 1.34ohms ,what kind of readings should I be getting? I think I am going to have to drive a spike.

 

[WayneL]

Alright guys, I have just been at a house to fit a 32amp pull cord, when I went to the consumer unit there was a 16mm earth coming from a cut out that was fed with just two tails ,this is a TT system ,so I did a Ze and got a reading of 1.34ohms ,what kind of readings should I be getting? I think I am going to have to drive a spike.

I'd say 1.34 ohms was pretty good for a TT system

 

[Sintra]

Alright guys, I have just been at a house to fit a 32amp pull cord, when I went to the consumer unit there was a 16mm earth coming from a cut out that was fed with just two tails ,this is a TT system ,so I did a Ze and got a reading of 1.34ohms ,what kind of readings should I be getting? I think I am going to have to drive a spike.

The 16mm earth coming from the cut out is strange for a TT

 

[vbyrne]

The 16mm earth coming from the cut out is strange for a TT

I dont think it is doing any thing some one has just connected it in there for the sake of it so what do you think is that a decent enough reading ,if so must be getting an earth from some where that is not visible