di-log earth leakage clamp

[bubachuba]

Does anyone own one, or have any views on them?
http://www.dilog.co.uk/_cm_DL6507.htm

 

[bernardgreen]

It might be useful PROVIDED [a] only the live and neutral conductors are inside the clamp or only the earth conductor is in the clamp. If the earth conductor and neutral conductor are both in the clamp then the leakage current in the Earth will be added to the current in the Neutral and this sum of neutral current plus leakage current will equal the current in the live conductor. Zero indication on the meter if the Live is also in the clamp.

Hence it cannot be relied on when the cable is twin and earth

 

[bubachuba]

hi bernard,
thanks for posting. yes, i have found them useful for clamping the tails/earth tail on TT/TNS or for checking current draw using the single core from the mcb. Just wondered if anyone had one as they are about £70 cheaper than the Kewtech equivalent and also has a 2 year warranty.
cheers

 

[EFLImpudence]

Yes, I have one of these. Different brand but exactly the same and even cheaper.

http://www.test-meter.co.uk/tm-el9809-earth-leakage-clamp-meter/

It's fine. Better spec than some dearer ones.

 

[EFLImpudence]

Not sure of Bernard's points.

It's a clamp meter; that's how they work.

 

[bubachuba]

Yes, I have one of these. Different brand but exactly the same and even cheaper.

http://www.test-meter.co.uk/tm-el9809-earth-leakage-clamp-meter/

It's fine. Better spec than some dearer ones.

thanks for posting EFLI. Thats good to hear and as you say, cheaper again! I have heard some people say they can get bum readings from nearby cables (such as the vast amount inside a CU) - is this something you have noticed?

 

[JohnW2]

Not sure of Bernard's points. It's a clamp meter; that's how they work.

It is. However, I presume his point relates to the description of these devices (e.g. in the link you provided, and the title of this thread). they would only be usable for measuring 'earth leakage' if only the earth conductor (or L & N but NO earth conductor) went through the clamp - which is often going to be quite difficult to arrange.

Kind Regards, John

 

[bernardgreen]

My point was that a clamp meter is no use at detecting earth leakage when clamped round length of twin and earth.

I didn't know how knowledgeable bubachuba about the use of the item. As it appears to be sold as an "earth leakage detector" one could be forgiven for thinking it would detect earth leakage currents when clamped around a twin and earth cable. ( some years ago an "electrician" did just that ).

Clamped around twin and earth it would indicate un-balance ( Live - Neutral ) if the leakage was directly to Ground and not to the CPC.

 

[EFLImpudence]

thanks for posting EFLI. Thats good to hear and as you say, cheaper again! I have heard some people say they can get bum readings from nearby cables (such as the vast amount inside a CU) - is this something you have noticed?

Not really.

Not an expert but if it only measures the current inside the clamps how could that happen?
Wouldn't that mean it would give a reading if you just poked it in the CU without clamping any wires?

 

[JohnW2]

thanks for posting EFLI. Thats good to hear and as you say, cheaper again! I have heard some people say they can get bum readings from nearby cables (such as the vast amount inside a CU) - is this something you have noticed?

Not really. Not an expert but if it only measures the current inside the clamps how could that happen? Wouldn't that mean it would give a reading if you just poked it in the CU without clamping any wires?

I don't really understand what you're saying. It will only measure current in whatever conductors are 'within the clamp', and will give you the 'vector sum' of the currents in whatever conductors are in the clamp. With a 2-core (L and N) cable, that 'vector sum' would be the difference been L&N currents - hence probably 'earth leakage'. With 3-core cable (e.g. T&E) it would be the difference between L and (N+'E') currents. As bernard says, that would mean that the displayed 'vector sum' would again be the 'earth leakage' if the leak were 'direct to earth', but if (as much more commonly) it were an L-CPC leak, then it would read zero, since (N+CPC) current would be equal to L current.

Kind Regards, John

 

[EFLImpudence]

My point was that a clamp meter is no use at detecting earth leakage when clamped round length of twin and earth.

Quite. Nor is anything else.

I didn't know how knowledgeable bubachuba about the use of the item.

Fair enough.

As it appears to be sold as an "earth leakage detector"

That's what they are called.

one could be forgiven for thinking it would detect earth leakage currents when clamped around a twin and earth cable. ( some years ago an "electrician" did just that ).

Well, I suppose it would but not if you know what you are doing.

Clamped around twin and earth it would indicate un-balance ( Live - Neutral ) if the leakage was directly to Ground and not to the CPC.

Yes, but that's not how they should be used.

Perhaps some people think Clamp Meters measure clamps.

 

[EFLImpudence]

thanks for posting EFLI. Thats good to hear and as you say, cheaper again! I have heard some people say they can get bum readings from nearby cables (such as the vast amount inside a CU) - is this something you have noticed?

Not really. Not an expert but if it only measures the current inside the clamps how could that happen? Wouldn't that mean it would give a reading if you just poked it in the CU without clamping any wires?

I don't really understand what you're saying. It will only measure current in whatever conductors are 'within the clamp', and will give you the 'vector sum' of the currents in whatever conductors are in the clamp. With a 2-core (L and N) cable, that 'vector sum' would be the difference been L&N currents - hence probably 'earth leakage'. With 3-core cable (e.g. T&E) it would be the difference between L and (N+'E') currents. As bernard says, that would mean that the displayed 'vector sum' would again be the 'earth leakage' if the leak were 'direct to earth', but if (as much more commonly) it were an L-CPC leak, then it would read zero, since (N+CPC) current would be equal to L current.

But bubachuba said he had heard that this model could be affected by other wires outside the clamp.

 

[bubachuba]

Hi.

they would only be usable for measuring 'earth leakage' if only the earth conductor (or L & N but NO earth conductor) went through the clamp - which is often going to be quite difficult to arrange.

Sure, that is a very valid point, but my method of attack for leakage is the entire installation first (either the tails combined, or main earth on its own), followed by individualy circuits if necessary.

My point was that a clamp meter is no use at detecting earth leakage when clamped round length of twin and earth.

I didn't know how knowledgeable bubachuba about the use of the item. As it appears to be sold as an "earth leakage detector" one could be forgiven for thinking it would detect earth leakage currents when clamped around a twin and earth cable. ( some years ago an "electrician" did just that ).

Clamped around twin and earth it would indicate un-balance ( Live - Neutral ) if the leakage was directly to Ground and not to the CPC.

Thanks Bernard, valid point. I am an electrician who does not fall in to that category although perhaps many others!

Not an expert but if it only measures the current inside the clamps how could that happen?
Wouldn't that mean it would give a reading if you just poked it in the CU without clamping any wires?

You would think so wouldn't you, but i have heard other sparks claim that this does happen when in close proximity of other loaded cables which is one of the reasons of me asking about this particular model: I wondered if the more expensive models (like the Kewtech 2434) were less suscepticle to such allegations!

 

[bernardgreen]

they can get bum readings from nearby cables

Clamped around the CPC of a cable they may give a reading of leakage current when that circuit is completely free of any faults.

Current from a earth fault will divide at the earth bar in the CU and flow along all available parallel paths to ground. Leakage from ( for example )the kitchen sockets flows back to the earth bar and then most flows along the main earth direct to the MET. But some will also flow ( for example ) from the earth bar along the CPC to the boiler, across the gland plate to a water pipe. along the water pipe to the main water bonding point and then along the bond wire to the MET. and also via the gas pipe from boiler to bonding of the income gas pipe and thus to the MET. Boiler is free of any fault but there is current flowing in the CPC to the boiler. Likewise immersion heater and electric showers.

 

[EFLImpudence]

Not an expert but if it only measures the current inside the clamps how could that happen?
Wouldn't that mean it would give a reading if you just poked it in the CU without clamping any wires?

You would think so wouldn't you, but i have heard other sparks claim that this does happen when in close proximity of other loaded cables which is one of the reasons of me asking about this particular model: I wondered if the more expensive models (like the Kewtech 2434) were less suscepticle to such allegations!

I don't know, then.