MFT for a DIYer?

[Pete999]

Sorry not sure what your question is, as I see it your last post says "ined from using an MFT ? you are a DIYer are you not"

Sorry mate blooming computer givin me grief

 

[buzzlightyear]

What makes you think that, surely the point of testing is to make sure the circuit is safe so will not injure anyone. There's lots of instructional stuff on how to use one correctly, and its something I'm keen to learn for my own interest

do you know about ohms or Kirchhoff's law & the electricity work act & heath and safety and your house liability insurance .

 

[Steve T]

do you know about ohms or Kirchhoff's law & the electricity work act & heath and safety and your house liability insurance .

The first two, yes to some extent and I'm keen on learning about that sort of thing.
I am aware of the electricity work act and health and safety stuff. As for insurance as far as I'm aware diyers are allowed to do some electrical jobs in their own homes.

 

[buzzlightyear]

I am aware of the electricity work act and health and safety stuff. As for insurance as far as I'm aware diyers are allowed to do some electrical jobs in their own homes.

not really try and tell that to the insurance company ,nil and void .

 

[pc1966]

The first two, yes to some extent and I'm keen on learning about that sort of thing.

It is good that you wont to do things properly and realise that being able to test your work before and after energising is part of that. However, from the above comments the folk here are a bit concerned that learning via YouTube with a MFT is potentially a very dangerous hobby.

Many of the MTF measurements are "live" tests with things energised, they are obviously dangerous. However, the "dead" testing before that can be far more dangerous if the equipment is if fact live and you did not know that.

So the first step you ought to learn is the safe isolation process, and that means looking for a decent voltage tester and (ideally) a proving unit first. Never rely on a mlutimeter or MFT to prove dead, there are so many ways that can go wrong.

 

[Steve T]

It is good that you wont to do things properly and realise that being able to test your work before and after energising is part of that. However, from the above comments the folk here are a bit concerned that learning via YouTube with a MFT is potentially a very dangerous hobby.

Many of the MTF measurements are "live" tests with things energised, they are obviously dangerous. However, the "dead" testing before that can be far more dangerous if the equipment is if fact live and you did not know that.

So the first step you ought to learn is the safe isolation process, and that means looking for a decent voltage tester and (ideally) a proving unit first. Never rely on a mlutimeter or MFT to prove dead, there are so many ways that can go wrong.

Thanks for your reply. I understand your concerns about possible danger, I should make it clear that I'm absolutely not planning on rushing to use one on my installation without having a good grasp on how it works and how to do things safely. I was actually considering making up a little 'mock installation' in my garage not connected to anything to teach myself how to use an mft before going anywhere near live testing or a real installation. I actually already have a gs38 voltage tester that I bought new a couple of years ago and I appreciate the need to prove dead. I don't have a proving unit though, I have just tested my voltage tester on a live supply before and after using it to check something is dead instead. Do you think that sounds like a sensible way to go about it?

 

[loz2754]

What ever you buy make sure you buy it with a Credit Card not PayPal, they just closed a resolution on my account even though I did not receive the item, the seller some how managed to get a Royal Mail tracking that said I had received even though I had not, no recourse to PayPal, but you could get reimbursed by your Credit Card.

PayPal sucks

 

[Steve T]

Thanks for your reply. I understand your concerns about possible danger, I should make it clear that I'm absolutely not planning on rushing to use one on my installation without having a good grasp on how it works and how to do things safely. I was actually considering making up a little 'mock installation' in my garage not connected to anything to teach myself how to use an mft before going anywhere near live testing or a real installation. I actually already have a gs38 voltage tester that I bought new a couple of years ago and I appreciate the need to prove dead. I don't have a proving unit though, I have just tested my voltage tester on a live supply before and after using it to check something is dead instead. Do you think that sounds like a sensible way to go about it?

I also want to add I'm not trying to play at being an electrician, I'm just interested. I've got no problem using an electrician where required, for instance I had an electrician do a fairly extensive garden light installation a few years back as that was clearly out of the remit of diy, even though I probably 'could' have done it. I only do the smaller things myself as I actually enjoy it?

 

[telectrix]

going back to the OP. the 3rd link looks a good buy from where i'm drinking sitting. be prepared to go up to £200.

 

[Lister1987]

It is good that you wont to do things properly and realise that being able to test your work before and after energising is part of that. However, from the above comments the folk here are a bit concerned that learning via YouTube with a MFT is potentially a very dangerous hobby.

Many of the MTF measurements are "live" tests with things energised, they are obviously dangerous. However, the "dead" testing before that can be far more dangerous if the equipment is if fact live and you did not know that.

So the first step you ought to learn is the safe isolation process, and that means looking for a decent voltage tester and (ideally) a proving unit first. Never rely on a mlutimeter or MFT to prove dead, there are so many ways that can go wrong.

I'd go so far as to say ALL MFT tests are 'live tests' on the spirit of EAWR (Injection of a charge into a cable them males that cable charged).

(Anally retentive extracts below)

Charged/live (as used in regulations 8, 13 and 14)
47 The terms ‘charged’ and ‘live’ have different meanings; they are not defined in
the Regulations so they take their ordinary meaning. ‘Live’ means equipment that is
at a voltage by being connected to a source of electricity. ‘Charged’ means that the
item has acquired a charge either because it is live or because it has become
charged by other means, such as static or induction charging, or has retained or
regained a charge due to capacitance effects even though it may be disconnected
from the rest of the system.

Live work
50 Live work is work on or near conductors that are accessible and ‘live’ or ‘charged’.
Note that testing of live exposed conductors using a test instrument is live work.

?

 

[timhoward]

We all have to start somewhere, and it sounds like the OP has the crucial common sense element. Good idea to practise on a rig in your garage. You can practise continuity tests and insulation resistance tests with everything dead (or ok, dead when not sending 500v through it!). MFT's will usually tell you if you are connected to a live supply (though this does not remove the need to prove dead first). Whatever MFT you get please obtain and study the manual so you know exactly what it is doing.
Many MFT's are on ebay because they are older models that don't have features that are frequently needed these days, for example 240v dc insulation tests, or no-trip loop impedance tests designed to not activate an RCD. If something is cheap there is usually a reason!

At risk of being shot - there are some really good youtube videos about testing, as well as some positively scary ones. If you want a recommendation you could do worse that to study the videos made by John Ward. (Google "John Ward Testing"). Be safe!

 

[pc1966]

Having a test rig to get some experience in a reasonably safe manner is a good start. My 2p worth of advice would be:

• The supply to the test rig has to be RCD protected. Double-check the house has working RCD protection on the sockets.
• Double-check that the socket RCD protection is not shared by the light circuit, otherwise when you invariably trip it you would end up in darkness.
• Have the test-rig supply from a plug and 3A fuse to the rig. A low value HRC fuse will serve to limit the fault energy better than a typical MCB in a CU.
• If you want to measure a test-rig RCD or RCBO trip-behaviour with the MFT then put the MFT's L & N leads on the RCD load as you normally would do, but put the MFT's E lead to the test-rig N before the RCD being tested (instead of the supply E). That way the trip-current used by the MFT will be an imbalance as seen on the test rig, but not on the house RCD (so it should not trip).

 

[Risteard]

What ever you buy make sure you buy it with a Credit Card not PayPal, they just closed a resolution on my account even though I did not receive the item, the seller some how managed to get a Royal Mail tracking that said I had received even though I had not, no recourse to PayPal, but you could get reimbursed by your Credit Card.

PayPal are appalling for protection both with business accounts and personal accounts.

 

[Lister1987]

If you want to measure a test-rig RCD or RCBO trip-behaviour with the MFT then put the MFT's L & N leads on the RCD load as you normally would do, but put the MFT's E lead to the test-rig N before the RCD being tested (instead of the supply E). That way the trip-current used by the MFT will be an imbalance as seen on the test rig, but not on the house RCD (so it should not trip).

Genius, I would have thought of that.

 

[timhoward]

If you want to measure a test-rig RCD or RCBO trip-behaviour with the MFT then put the MFT's L & N leads on the RCD load as you normally would do, but put the MFT's E lead to the test-rig N before the RCD being tested (instead of the supply E). That way the trip-current used by the MFT will be an imbalance as seen on the test rig, but not on the house RCD (so it should not trip).

Any idea why this wouldn't work on a 30ma RCD fused spur for a whirlpool bath? There was a 30ma RCD on the CU too. I had phase and neutral probes on the load, and earth probe on the incoming neutral, and both RCD's tripped each time. I put it down to it being an older device, but other thoughts welcome!