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Topic Title: Martindale ET400
Topic Summary: any users?
Created On: 17 August 2015 04:21 PM
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 17 August 2015 04:21 PM
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Zs

Posts: 3830
Joined: 20 July 2006

Hello,

My Megger went in for calibration this morning and failed, requiring repair by Megger.

£348.80 for the repair
£55.00 for calibration (as an extra..I'm shocked)
plus VAT.

So, I've just had a conversation about a new multifunction tester and I rather like the look of the Martindale ET4000 because it displays all the RCD test results on the one screen without having to scroll and it has a tick for when a Zs reading complies with Amd 3 on the screen.

£475+VAT with a few extra little toys thrown in. Martindale are only a half hour drive from Zs Towers so service becomes less of a hassle (Megger are in Dover).

I'm inclined to order one straight away but think I should ask you first if you have any horror stories. How is the no-trip loop testing?

Thank you in advance,

Zs
 17 August 2015 04:53 PM
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Zs

Posts: 3830
Joined: 20 July 2006

http://instrotech.com/martindale-et4000-p-2335.html

That should be a link to it but I'm having trouble getting it to work as usual.

Apologies for the typo in the title bar. I refer to the 4000 model.

Zs
 17 August 2015 05:49 PM
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leckie

Posts: 4439
Joined: 21 November 2008

I've not seen those, they are obviously quite new. Metrel also do a low cost meter. I had a quick go on one of them and it seemed OK. I think you can get them for about £520 inc VAT.

Let me know how you get on, my Megger 1500 series meter is getting very old now so I expect it will conk out soon!
 17 August 2015 09:17 PM
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John Peckham

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Zs

How old is your Megger? They have a 3 year warranty so if less than 3 years old you should get a free repair.

What range(s) was it out of calibration?

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 17 August 2015 09:31 PM
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GeoffBlackwell

Posts: 3797
Joined: 18 January 2003

The specification does not set the world alight.

Looking at loop impedance testing you have a test current of 6.5 A for 10 ms (half a cycle). My Fluke is 12A for 10 ms and my Megger 25A for 40ms.

They include a note: 'The accuracy is valid if the mains voltage is stable during the measurement.' The range is 0.25 ohm to 9.99 kohm - as are most of the others available.

Still you get what you pay for - it is as good as most in the domestic environment, and as bad as most on high energy industrial supplies.

Can I interest you in a gold plated spanner .

Regards

Geoff Blackwell
 17 August 2015 09:37 PM
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daveparry1

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Buy a Fluke Zs, you know it makes sense!
 17 August 2015 09:40 PM
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leckie

Posts: 4439
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Ah that interesting Geoff. So why have you got a Fluke and a Megger? Is one better than the other, and if so why? Well in your experience and opinion.

I've only ever had Megger / Avo for forty odd years, so I have only a little idea what the others are like on a day to day basis.
 17 August 2015 09:56 PM
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GeoffBlackwell

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Leckie
The choice between them is a matter of personnel preference. They both do the job. I prefer the Megger but that is just my choice.

The Fluke is little used. I bought it as an emergency replacement for the Robin unit I was using at the time (cost around £700 - includes a three electrode earth rod testing kit).

The Megger just suited the way I tested (past tense as I have not done any I & T for a couple of years now).

Regards

Geoff Blackwell
 17 August 2015 10:40 PM
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deecee

Posts: 38
Joined: 20 October 2005

Hi Zs, long time no speak.
We had an older version of a martindale multi function tester at the college and I have to say it was terrible, more of a random number generator and I could never work out the relationship between Ze readings and PFC it displayed.
This new one looks more conventional but have they improved the accuracy? and are there free software updates when the maximum Zs values change again.
Having played testers from most manufacturers, personally I would go for the fluke or kewtech.
 17 August 2015 11:13 PM
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Zs

Posts: 3830
Joined: 20 July 2006

'Looking at loop impedance testing you have a test current of 6.5 A for 10 ms (half a cycle). My Fluke is 12A for 10 ms and my Megger 25A for 40ms.'

That's interesting Geoff. Thank you for delving. I finally found that on page 68 of the manual and not in the tech spec page of the web site.

So, does that 6.5A have an impact on test readings taken from normal domestic and commercial? I am mostly involved with commercial inspections these days, very few domestic, very few single phase. Is it likely to affect accuracy?

Having been the owner of a Fluke and a Megger with their different current ratings I can't say I noticed anything. The Fluke remains closest to my heart. It used to take a long time to return a low current loop test result and the Megger, well, not quick either of course.

That price is a discount and seems to correlate with the Megger MFT 1730 on the web.

JP, apparently it is low on the 0-1 ohm no trip loop testing so that means the readings I have been getting are high. That's from the girl who booked me in though and she admits to not being technical. Nothing else wrong. It is out of warranty, I think since last November. However, no question, a second opinion will be sought from an alternative calibration service and I'll let you know the outcome of that. I'll probably get it down to your guy because I know he is experienced and respected.

At well over £1000, wasn't it about £1600 in those days? for the initial purchase nearly £500 for a repair I'm afraid that puts me right out of the Megger camp for good. I looked into sending it there myself but they're after a huge amount for that too. Let's face it, I've never been particularly gruntled by the MFT1730 as you re all aware.

It is a shame I don't have time to take this at a more measured pace but I need my test equipment for normal use and I have my inspection in less than a fortnight. So I am a little bit stuffed. otherwise I'd borrow one and take it out on site before deciding.

Probably time I had a spare but we'll see about that repair cost.

How can someone fix a meter and then charge the client for the calibration on top of it? That's Megger, not the supplier because they mailed me the quote. Surely the calibration is part of the process like setting the wheels on a car facing the front?

Oh well,

thank you,

Zs

edit: deecee how lovely to see you pop up. Made my day. Yes, I remember the martindales from college but in those days, to be as honest as I dare be, the numbers didn't mean much to me and I just wrote them down. Nowadays I'll make a bet with myself as to what a reading is going to be before I even press the button.

I am beginning to have my doubts and am glad I asked. I'll get some comments from the supplier tomorrow.

Zs

Edited: 17 August 2015 at 11:26 PM by Zs
 17 August 2015 11:23 PM
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stateit

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Originally posted by: Zs

Surely the calibration is part of the process like setting the wheels on a car facing the front?


Blooming tyre shops charge for tracking after a wheel change as well

-------------------------
S George
http://www.sg-electrical.com
 18 August 2015 12:20 AM
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alancapon

Posts: 6941
Joined: 27 December 2005

Originally posted by: Zs
. . . apparently it is low on the 0-1 ohm no trip loop testing so that means the readings I have been getting are high. That's from the girl who booked me in though and she admits to not being technical. Nothing else wrong. It is out of warranty, I think since last November. However, no question, a second opinion will be sought from an alternative calibration service and I'll let you know the outcome of that. . .

I am always a bit suspicious of some of the calibration services. Our metering department have a "calibration machine" which is used to calibrate all our test instruments. The machine itself is calibrated once a year. Following the instructions, our instruments have to spend between 12 and 24 hours in the same room as the machine before calibration, as the recommendation is that they need to be at the same temperature / humidity as the machine during the calibration process. The machine also has its own LV supply from our substation to ensure it sees a stable supply.

On the subject of the Martindale MFT, we have one to see what we think of it. I have not (yet) managed to get my hands on it. I will have to find out where it is. We did put it on our calibration machine when we got it, with the intention of doing it again after a few months to see how the results compared.

Regards,

Alan.
 18 August 2015 06:07 AM
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GeoffBlackwell

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Zs said
So, does that 6.5A have an impact on test readings taken from normal domestic and commercial? I am mostly involved with commercial inspections these days, very few domestic, very few single phase. Is it likely to affect accuracy?


You are doing the test to verify the impedance of the Earth Fault Loop Path and in this role - given a fair wind the three instruments considered Fluke 12A /10 ms, Megger 25A / 40 ms, and Martindale 6.5A / 10 ms - are all capable of giving a valid result.

The fair wind requires that the supply voltage is stable during the test and that any 'noise' is minimal. You should note that all of these instruments have a lower range limit of around 0.25 ohms. This means that there are no guarantees on circuits with a lower impedance. Also note that the standard allows for errors as high as 30% in some conditions.

In the domestic installations, provided the sub-station is not next door , you should get reasonable results.

In the commercial / industrial installations it will all depend on how close you are to the supply source and on the impedance you are trying to measure.

Note that in a work place you are in EWR territory and you need to take note of Regulations 5 and 8.

None of these instruments provide a verification of the ability of the circuit to handle large fault currents, as the energy injected during their tests is minute compared to the energy a fault may dissipate.

The instrument I recently presented to you all from Megger goes some way to addressing this but at a price tag in the region of £6k.

In comparison my golden spanners are cheap as chips .

Regards

Geoff Blackwell
 18 August 2015 09:27 AM
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Cremeegg

Posts: 679
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Just a thought or two - why not get a calibration card or checkbox or similar. When you have your meter calibrated - check the readings against the check box. You can then carry out your own calibration check whenever you have doubts about your meter. My assessor is happy to see my results for that done on a monthly basis even though my calibration certificate is no longer valid. From many months of tests I now know that my Megger 1520 will start to give unreliable readings when the battery voltage is below 10.4v.

I know you're not a fan of our "friends" in Dover but I had my meter repaired FOC by them two years ago when it was about six months out of warranty and returned with a new calibration certificate. A few hours argument on the phone but I eventually got what I wanted - the only downside was I had to take it to them and have a day out in Dover - not too bad as it was a summers day spent sitting on the top of the cliffs eating ice cream and watching the ferries.
 18 August 2015 01:51 PM
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daveparry1

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I've been using only my Calcard for about five years now, keep a monthly check record and never had any problems at assessment time.
 20 August 2015 09:12 PM
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Zs

Posts: 3830
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Good Evening from Zs Towers.

I made a decision with some help from the chaps at Instrotech in Watford. Blatant publicity there because I love it when people pick up their phones.

My major concern is that one of my clients won't be happy if I buy a piece of kit which is not 'the kit' that everyone uses. I know he loves Megger. He'll be seeing this, he is one of ours. I don't want to lose his business by not having a Megger but I need to move on from them.

However, I saw yellow boxes on one of his sites only about three weeks ago and I don't think they were for sandwiches.

I am concerned about the random number generation mentioned by deecee a few days' ago so I put in a call to the supplier from my earlier link. I explained my requirement for accuracy.

They have agreed a 14 day sale or return on the Martindale ET4000 which is fantastic. I will be going over to sort it out tomorrow.

I would very much like to do some comparison with Megger and Fluke. Mostly for the peace of mind of an important client. Apart from the failed calibration on low current EFLI on the Megger I suppose I've got that sorted so I can report back on that but I might well be asking to borrow some kit from you or share a nerd-fest checking them out.

Dave Parry - You are the Flukemeister - I make great tea but I have to go out and buy the cakes because I'm not very good at those. My Mum is very disappointed in me for that but I suppose we can't have everything.

I'll be the one with the one with the Martindale then. Genuinely, I want to tell you good things about it because I am conscious that I am going off-piste with this purchase.

Zs
 21 August 2015 05:28 PM
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Zs

Posts: 3830
Joined: 20 July 2006

Good news and bad news...

The good news is that it is a neat bit of kit and at first impression it is going to be no more difficult to use than the Fluke was and miles more user-friendly than the Megger 1730 is. Dave, it makes the same noises as the Fluke and is quicker than the Fluke and the Megger. I'm glad to have the aural indication that a test is in progress back. Very glad in fact.

I'll give you a complete run-down once I've got a handle on it. Already I can see that there is lots to tell you.

The bad news is that it is a three lead tester. I suggested that that is actually going to be a deal-breaker over the 14 day sale or return period but now I'm wondering about that.

It means the indicative (non-approved but sometimes useful) Z test whereby you nick the line from a different local circuit becomes pretty spurious because it would mean nicking the neutral as well. I have used that test in situations such as using a long pole to test that an appliance has an earth on many occasions. However, driving home with the deal-breaker thing in my head I found myself realising that I don't use it very often these days and if it's just proving a cpc then using the rogue circuit neutral as well doesn't exactly blow it out of the water. Well, ish. Not much use for proving path to earth on a TN? Not forgetting the trusty long green lead and the old fashioned way of course.

The sales guy said that testing at a light switch was gone but I absolutely cannot remember the last time I used a light switch to get a Zs. I go inside the last light on the circuit all the time these days because it covers a % of the visual inspections.

So I'm not sure what I'm worrying about really.

Geoff if you are out there; I've just had a cruise through some old threads about EFLI testing and found your explanation of the voltage difference and ohms law being the result that comes up on the screen, but have not found what I am looking for. If you have time (not urgent) could you explain how a tester is working when doing EFLI with three leads and with two? I am wondering if the two lead test involves internal calculations much more than special testing techniques. Consequently, I'm thinking what happens if I link the N and E probes into one on a TN system but I'm not about to try it out.

This one definitely won't run a test without the three leads in place and annoyingly it also knows when you're swapping them around. However, the 'Z line' function appears to do the swapping for testing down the neutral instead of the earth. I've not been one for testing down the neutral since having a two lead tester so I think that will only be for the PSC which it brings up but I know that some of you use that quite often on TN final circuits so I guess that's for you. What the Megger does on Z high current for those who don't swap leads around

At the moment I'm only messing with the low current or 'RCD Loop' as they call it because I don't want to trip things.

There's something else in the Z line function with what I think are a range of delta U percentages and I'm clueless at the moment.

I will put the disk into the computer over the weekend and read the manual.

My failed Megger shows me a Zs of 0.32 on the same socket outlet as the Martindale shows me 0.25. Both show 248V and I'll not rattle on about the True RMS on one of them...Same number. I'll run that one with JP when he has his next calibration coffee morning because I'll take the Megger over for that so we can play with this one.

It seems OK and has some rinky-dinks that will be useful. Provided that the numbers are OK.

Zs
 21 August 2015 06:38 PM
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Chris123

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Joined: 08 February 2010

Hi Zs

I have a feeling this tester for "No trip" uses a 3 wire method, sometimes a bit of a fiddle, my Megger is a three wire, one day i will upgrade.

Chris
 21 August 2015 07:37 PM
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GeoffBlackwell

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Zs said
Geoff if you are out there; I've just had a cruise through some old threads about EFLI testing and found your explanation of the voltage difference and ohms law being the result that comes up on the screen, but have not found what I am looking for. If you have time (not urgent) could you explain how a tester is working when doing EFLI with three leads and with two? I am wondering if the two lead test involves internal calculations much more than special testing techniques. Consequently, I'm thinking what happens if I link the N and E probes into one on a TN system but I'm not about to try it out.


Most testers detect the voltage drop caused by the test current to determine loop impedance. They may also correct for phase difference between voltage and current.

This can be achieved with a a two wire test but some require that you use three.

One of the manufacturers wrote an article in the technical press that gave an explanation for this but I can't find it.

My best guess is that the neutral is required to help maintain a constant voltage for the internal electronics during the test.

I have shorted neutral and earth on some instruments (Fluke and Robin) without damage but you should clear this with the manufacturer. It will probably reduce accuracy.

Regards

Geoff Blackwell
 21 August 2015 08:03 PM
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sparkingchip

Posts: 10180
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I added Megger LTW315 two wire no trip loop tester to my kit , lovely tester, but so'oooooooo slow carrying no trip testing it doesn't get used where a neutral is available for the three wire testers.

Andy
IET » Wiring and the regulations » Martindale ET400

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