Interesting one.

[gselectrical]

I was called to a Caravan Park earlier. Reports of RCD's tripping. I had a similar situation a while back where I posted about it on here. Received loads of help and info from Sidewinder. (Thanks again)

Anyway. When I got there I was told that RCD's within a few hookups and the main toilet block had been tripping at the same time (not sure whether is was exactly the same time or cascade)

I have attached an image below of what I found. The door of the Square D 3 phase DB was pushed up against the metal enclosure (by a piece of ply within the mains room) housing the 3-phase cutout & meter. You can see in the picture where there has been some sort of arcing due to the 2 different earthing systems in use.

To confirm, I tested the Ze at the Square D board. 116ohms (TT system). I then clamped the earth lead to one of the screws securing the metal enclosure of the meter/cutout. 0.15ohms (TNC-S) system.

Now, could this cause the RCD's to trip?

The reason I ask this is because when I carried out a L-N loop test at the 3 phase Square D board, I got 16ohms. Even though I got 0.15ohms when testing L-E loop of cutout/meter.

Your thaughts on this one would be much appreciated.

GS

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[Andy™]

16 ohms L-N loop is seriously wrong

 

[ProDave]

The reason I ask this is because when I carried out a L-N loop test at the 3 phase Square D board, I got 16ohms. Even though I got 0.15ohms when testing L-E loop of cutout/meter. Your thaughts on this one would be much appreciated.

That 16ohms sounds somewhat high.

TNCS supply with failing neutral connection? (L must be okay as you got 0.15 ohms L-E)

 

[Andy™]

That 16ohms sounds somewhat high.TNCS supply with failing neutral connection? (L must be okay as you got 0.15 ohms L-E)

sounds about right. can only really be between head & point of measurement, otherwise Ze would also be high

 

[gselectrical]

Meeting DNO there on Wednesday. Earliest they could get their apparently. Cheers. Gs

 

[m4tty]

Let us kNow how you get on mate. Sounds interesting

 

[gselectrical]

Let us kNow how you get on mate. Sounds interesting

I was there for an hour this morning as I had a few other bits to sort out.

Thaught id re-test the L-N loop = 0.81ohms

Earth loop. L1-E = 0.14ohms

Im sure my testers are on their way out. Then again, they where fine on the following job.

I repeated the test 3 times on Monday following the 16ohms L-N loop, all with the same result.

?

GS

 

[m4tty]

What testers are they mate and when was last calibration?

 

[gselectrical]

What testers are they mate and when was last calibration?

Fluke 1653. They where calibrated 6 weeks ago. Although looking back, the Loop test was only a marginal pass. Think I need some new leads. Then again, shouldn't make a difference if they're nulled.

GS

 

[Sidewinder]

Ahh, now leads, is this an early unit mate?

The early Fluke 16xx series leads had quality problems, intermittent connections, that could be your gremlin.

They changed the manufacturer.

 

[Manator]

Ahh, now leads, is this an early unit mate?The early Fluke 16xx series leads had quality problems, intermittent connections, that could be your gremlin.

They changed the manufacturer.

Two of my testers had this problem

 

[gselectrical]

Ahh, now leads, is this an early unit mate?The early Fluke 16xx series leads had quality problems, intermittent connections, that could be your gremlin.

They changed the manufacturer.

It is an earlouy unit mate. To be honest I havnt been very impressed with them since I got them. Megger next I think! What's your thoughts on the image above side? Gs

 

[Sidewinder]

Stick with the Fluke mate, excellent kit, the new 1653b has advantages over the original, and the 1654 looks even better!

I'll have a look now at the image, though I would probably need more info really before commenting!

 

[ADS]

Fancy the new Megger MFT 1730 myself

http://www.megger.com/common/documents/MFT1700_DS_en_V02.pdf

 

[gselectrical]

Let us kNow how you get on mate. Sounds interesting

Quick update

I don't think there is a problem with the N connection. Testers playing up again. Since I have moved the DB (to prevent contact between the door and the DNO's cutout as shown in the picture) There has been no RCD's tripping. Hopefully this was the problem. Strange one though!

As far as testers go. The Fluke and the Megger both look great. Bit pricey though! Oh well. Hopefully the 1p a litre on fuel I'm gona be saving from now on will contribute towards some new testers. Them new flukes will be mine by 2025.

Cheers

GS

 

[kme]

I noticed Wednesday morning that three local supermarkets were putting the fuel UP by a penny - at lunchtime; following the budget announcement, they made a big show of taking it back off again. Robbing gits!

GS - the "arcing" that appears to have occured on the front of that panel could have an effect on downstream RCDs (check the RCD info previously posted last year....). I`d have concerns about any possible p.d. between the enclosures too, TBH.

My Fluke leads were replaced FOC by Fluke, when we had problems with `em - haven`t looked back since (with a nod of gratitude to Megger Mark ).

KME

 

[gselectrical]

Whats the best thing to do? PM megger mark for a price?

Cheers GS

 

[kme]

If you`re on original Fluke leads - try talking to Fluke first - mine was 3 tr old when they changed the 3 pin plug lead for me......

As for the seperates - MegMark is the man!!!! In my experience, anyway.....