Handy bit of kit

[Gees]

Hello guys. I just got one of the new socket testers from martindale.
It works a treat and is Foolproof. See http://www.martindale-electric.co.uk/ for details.
I do NOT have any connection to the above company.

 

[breezer]

screwfix have them and are cheaper (sorry) see here

 

[Gees]

Breezer.. I am supplied with these things for free..... Part of Job.
Also the screwfix one doesnt do earth loop impedance test ( or does it )
Checked my supply here and the reading agrres with my LT7 so its a gud un.

 

[breezer]

its all right for some (supplied for free) but for the average diy person the screw fix one is fine. are you sure it is earth loop impeadance yours does, to check if there is an earth yes, earth loop impeadance hmmmmm, but i could be wrong.

but yes the screwfix one does check to see if there is an earth (and it is in the right place)

 

[Gees]

Yes it does a proper loop test and whats more does it without tripping the rcd. I was amazed myself because the Megger lt7 I have here ( also supplied ) costd hundreds of quid.
If a person ever wondered if his earth is OK then there you go...

 

[breezer]

how many did you say you had? are you sure you haven't lost it in my direction?

 

[Gees]

Sorry Breezer only got one...........There is a PDF document on the web site.

 

[spark]

Be careful folks, these things are not fool-proof and will not tell you about neutral and earth reversals for example. It's not a loop impedance tester either, it only gives you a ball-park figure. The idea of loop testing is to ensure that your loop impedance value is within the limiting values tabulated in BS7671:2001. These tabulated values tell you whether the circuit's protective device will operate within the time it needs to. If you've got a borderline reading it will not show using this tester and could make the difference between the protective device operating or not. You may have a great earth, but if it's outside the tabulated limiting value it's almost pointless. They've tried to cross a complex test instrument with a basic socket tester. The screwfix one is £8.49 the martindale is £59; I don't think it's worth spending the extra if you're a DIYer and if you're an electrician it won't save you anything because you should be loop testing every socket anyway. As Gee's said, it's great if it's supplied free, but personally I can't see who they are trying to aim this product at.

 

[Gees]

Spark.. you must have read the info cos as you say it cannot indicate a earth neutral crossover. But neither can my lt5???
Is there an instrument that can?

 

[spark]

Not to my knowledge Gees, all the socket testers I've come across have the same problem. Because generally earth and neutral are at the same potential, it's difficult for the tester to identify which is which. You're quite right, my loop tester also won't identify a neutral earth cross-over either; for the same reason. When I test ring circuits for polarity and continuity I use a low-reading ohmmeter (megger) and some test leads I made up exactly for that purpose. I can run through how I test for neutral-earth reversals if you like, but you may be aware already... It's the only way I know of; apart from 100% visual inspection which is also permitted but takes too long and if it's a periodic it can be hard to ensure you've included the whole circuit.

 

[Gees]

I thought there might be an easier way than using the low range of the megger. The way I know is probably the way you do it. I was not saying that these things would replace something like an LT7, but for the money they dont seem too bad.
For others reading this post the LT7 is a professional peice of kit for measuring earth loop impedance.
http://www.instruments4hire.co.uk/Megger_LT7_Digital_Loop_Tester.htm
for full information on the above