Insulation tester

[James Carmichael]

Hi all,

I'm a DIY-er who is after an insulation tester.

(Back story: I have - genuinely - an electrician who has worked with me before and is happy for me to do first fix then she tests at the end. However, I am fitting some electric underfloor heating and put the self levelling over it next week. She's not available, so I want to do a quick 'informal' insulation test now to make sure it's not obviously b*ggered before I commit.)

As this is a use-once-then-ebay-it device, I don't need professional grade features like an internal battery that lasts 1000 tests, ruggedised so it can be dropped down 10 flights of stairs, ergonomically designed, ... It just needs to work.

As far as I can tell there are three price points:
(1) Many unknown brand probably-direct-from-China options on Amazon at less than £50. I assume these just don't work?
(2) An array of about £100-150 own-brand style devices from lots of legitimate looking shops - try https://www.test-meter.co.uk/electrical-insulation-tester#product-tabs-navigation?
(3) Fluke, Megger, similar brand names at anything from £300 upwards to the stars.

What would you buy in this scenario?

Thanks

James

p.s. Yes, I know opinions vary on the efficacy of electric underfloor heating. Let's park that topic for another day.

 

[EFLImpudence]

Can you not hire one?

 

[RandomGrinch]

You could get some pretty meaningful results with a £10 multimeter - I would consider leaving the full insulation test to the electrician.

Examples here:

How to test an electric underfloor heating system

We guide you through one of the most important steps when installing electric underfloor heating.

www.thermosphere.com

 

[James Carmichael]

Hi,

Thanks for replies.

I've already done a simple resistance test with my multimeter - and the cables came out within the 5%-under margin specified.

I just quite fancy doing an insulation resistance test too. I don't think there's any particular complexity to it, is there, that would necessitate 'leaving it to the electrician'? Before I connect the mats to any type of supply, I connect the device to each pair of two cores in turn, dial round to 500V, press test. If the result comes out at greater than 2 mega-Ohms, job's a good un.

As I wrote, this is an 'informal test' to assess risk. The electrician can test it properly but if it's going to come out at 3 kilo-Ohms or something silly, I really want to be finding that nick before I pour £500 of SLC on top ...

Hiring one is a good idea - hadn't thought of that!

James.

 

[ericmark]

I have one of these, cost £35 when I could not find my Mega, since found, and the readings match each other. Seems now cheaper

same part number, but clearly not the same unit.

 

[James Carmichael]

Thanks @ericmark. That latest model you've found on AliExpress is also on Amazon under about a dozen different brands and price-points! However, if it does the job it does the job (which in this case is: Does it suggest a low risk that the real test will show lower than 2M-ohms) ...

I'll sleep on it but you may well have convinced me!

 

[ericmark]

I remember the old tester

I would get the apprentice, he was not daft enough to hold the leads, but I knew to grip them hard, and it would not build up voltage, so I would hold them first, then get him to hold them onto the item to be tested, then wind the handle. Same tricks done with an impulse mag.

However, when capacitor discharge ignition systems came in, my friend ending up in hospital, and we stopped doing stupid tricks, OK some healthy person may be OK, but how does one know if someone has a dicky hart, by the time you find out, it's too late.

These testers can kill, and not nice to get an electric shock anyway, I know on Sizewell two of us sent to same job, but neither know the other was also on the same job, and yes one got a shock when other guy using an insulation tester, and the guy with tester was getting odd results, foreman lucky for him was a good runner.

Do make sure there is someone with you, just in case, and be very careful.

What stopped me playing was when I thought I had killed a guy, I had spotted the wires, and know someone would try and give me a shock, when he came up, as he went to turn the leaver, I put my fingers on his neck, OK he was trying to get me, but he fell to the floor, and seemed not to move for a good few minutes, I was intending to teach him a lesson, it was me who got the lesson. OK I was only 18 at the time, now 73, but not forgotten it.

Be very very careful.

 

[thomp1983]

Where are you at, maybe someone local can help you out?

 

[Murdochcat]

Remember to test before you fit, after you fit and after the self levelling floor is poured

Couldn’t you get them to pop in? I’ve done that in the past

 

[James Carmichael]

I remember the old tester View attachment 360075I would get the apprentice, he was not daft enough to hold the leads, but I knew to grip them hard, and it would not build up voltage, so I would hold them first, then get him to hold them onto the item to be tested, then wind the handle. Same tricks done with an impulse mag.

However, when capacitor discharge ignition systems came in, my friend ending up in hospital, and we stopped doing stupid tricks, OK some healthy person may be OK, but how does one know if someone has a dicky hart, by the time you find out, it's too late.

These testers can kill, and not nice to get an electric shock anyway, I know on Sizewell two of us sent to same job, but neither know the other was also on the same job, and yes one got a shock when other guy using an insulation tester, and the guy with tester was getting odd results, foreman lucky for him was a good runner.

Do make sure there is someone with you, just in case, and be very careful.

What stopped me playing was when I thought I had killed a guy, I had spotted the wires, and know someone would try and give me a shock, when he came up, as he went to turn the leaver, I put my fingers on his neck, OK he was trying to get me, but he fell to the floor, and seemed not to move for a good few minutes, I was intending to teach him a lesson, it was me who got the lesson. OK I was only 18 at the time, now 73, but not forgotten it.

Be very very careful.

When I was about 18 I had a summer job in a local supermarket. One day I was in the warehouse out the back putting away some surplus stock when one of my friends came in. I threw down a bar of chocolate - "catch!" She reached out to catch it and went out of there on a stretcher. I have no idea how it did for her back but it was quite a few weeks before she was walking normally again.

I learnt the hard way that workplace messing about is just not worth it.

 

[James Carmichael]

Remember to test before you fit, after you fit and after the self levelling floor is poured

Couldn’t you get them to pop in? I’ve done that in the past

I've done resistance tests before unwinding (I'm loose wire, not mat, just because) and after laying. Both cables showed 41.8 ohms across all four measurements; so far so good.

My electrician is sadly overseas until the end of the year.

 

[blup]

I got a used megger IR tester from ebay being sold calibrated by a reputable commercial firm (checked them out) for a fraction of the new price.