Test Meter Recommendation

[orion.osiris]

If you hover the mouse over the picture it blows up very clearly. Clearly enough for me to now see that it's NOT auto-ranging on Current. D'oh!

[orion.osiris]

I know just the chap. Only qualified a couple of months ago and ticks all the above boxes. This is the kid who told me (just before qualifying) that "even a couple of Megaohms can kill you" and he even reads Nuts and Zoo, too. Perfect!!

[Archibald]

Rule number one, never stick both hands in a live "box"

Rule two, remember this is a DIY NG. I'm sure my meter would also be a little hazardous if I stuck it on a pylon!

Few people, myself included ever need to measure the incoming supply. Again any idiot can spend a fortune on equipment, but knowing how to use it is a different matter!

[John Rumm]

Do they protect your face from arc flash injury? (its not the shock risk you need to worry about in these cases!)

[John Rumm]

Sometimes it is not avoidable - especially if you need to work at a consumer unit. Note also that even a socket on a circuit close to a CU can pose a high energy source risk in some circumstances.

The cases where you will need a class IV meter are indeed likely to be few for a DIY situation. However there are plenty of situations where a class III device may one be required. A causal acquaintance with this group should furnish you with enough examples of domestic situations where people here have measured supply impedances below the resolution of their equipment (i.e. an indicated zero ohms)

True but not really relevant, since we are discussing the idiots who should be spending more on test equipment, but choose to wing it with substandard gear.

[Archibald]

This is a DIY NG. The scenario described is outside my and I'm sure many others scope of work in this NG.

Sadly, no. Perhaps you caqn enlighten?

AB

[dennis]

Its something to protect you from the leads as they vapourise that you need.

There isn't much chance of anything happening if you know what you are doing.

[orion.osiris]

I'm safe. I've got the same type of rubber gloves that vets use when they're feeling around for calves. :)

[The Other Mike]

The unshrouded terminals and lack of formal testing to to IEC 61010 / BS 61010

[John Rumm]

I am not sure why you think it is any different for a domestic environment. Domestic environments still have supplies that are high energy (especially in large towns, and for those living close to their substation), and still require equipment with a Cat III rating when working close to them. The risk from transient over voltage is the same, or in some cases higher (e.g. where the LV supply is via overhead wires).

Have a look at page 2:

The difference between cat II and III kit is fairly clearly explained.

Open a meter and look at the construction of a certified CAT III device, and then compare with some of the budget devices that also claims the same rating, but are not independently tested or certified. The difference can be substantial.

Now if you are comfortable working on high energy parts of a domestic installation using a basic multimeter that has not been designed for electrical installation testing, and does not have the recommended level of input protection, then by all means carry on, its your choice. Hopefully this discussion has made it clear to other readers that there are risks related to using inappropriate equipment, and now they are also it a position to make the same informed decision.

There are various tests required for electrical work laid out in BS 7671 (the wiring regs) that you won't be able to conduct at all using a normal multimeter, and there are some others that you can do, but they will require more effort, and take longer. Either way, you will need to decide if the effort / cost trade off it worth it, and also accept you may nott be able to prove that your work is up to the required standard. Again, if this does not concern you, carry on.

A consumer unit does not stop transients (although you will get a slight snubbing effect from the magnetic coil in the MCB). Hence it is possible to drive your test equipment into a failure inducing overvolt by connecting it at any point in a system.

What does change the further you move from the origin of the supply in a building, is the prospective short circuit current and the prospective fault current. Both fall as a result of the increasing loop and supply impedance (also the temperature rise introduced when small CSA wiring is driven into adiabatic heating under fault conditions, adds additional resistance). These factors conspire to make arc flash very much less likely in the first place, and far less damaging should it actually happen.

[orion.osiris]

OK, then how about one of those old fashioned diver's suits - the ones with the brass fishbowl helmet and lead boots? Will that suffice?

[tony sayer]

Very good pricing there, but the meters I have are fine as there're good quality ones they do last well:)...

Well if the design is right the components are the Same it matters not where they make them. I suppose there're made by machines for the greater part?..

[John Rumm]

You might look a bit of a prawn ;-)

Something like:

and a flame retardant jacket is more the norm when working on particularly risky situations.

[dom]

ntinue to study what's on the market. In the mean time, to replace my old W hite Gold meter from Maplin, I popped into my local Maplin store (better th e devil you know) and bought one of these by UNI-T. They're a chinese outfi t, but they make digital storage scopes so should know what they're doing:

interface-46458

From the UT60E manual:

(

)

This Meter complies with the standards IEC61010: in pollution degree 2, overvoltage category (CAT. III 1000V, CAT. IV 600V;)and double insulation. CAT. III: Distribution level, fixed installation, with smaller transient overvoltages than CAT. IV CAT IV: Primary supply level, overhead lines, cable systems etc.

However internal photos here:

(

)

Show non-HRC fuses.

[tony sayer]

Shouldn't there be some certification from an approval body to support that?..

[dom]

Read John Rumm's link to the article by Fluke. There's a body that sets the Class I-IV standard, but it's up to the manufacturer to self-certify compliance.

[dom]

I'm not certain, but the red and black stuff looks a lot like UNI-T

[Archibald]

I'm afraid the difference of a few mOhms due to heating effects would not really change my approach or assesment of the risks involved.

A DMM has an input impedance of 10MOhm or thereabouts. I'm sure the spike produced by the introduction of such a load would have world changing repercussions!

Someone carrying out DIY work can do it without the aid of a £100-00 DMM. I have yet to find a job that my Wickes DMM wasn't suitable for and that includes for professional use. In fact the only problem I might have on a site is the use of a "not calibrated for indication only" label. Apart from this it is an acceptable tool! As I stated before, any idiot can spend a fortune on test equipment, but that does not mean they can use it correctly.

There are a few little rules your flight of fancy does not take into account incidentally. No one should work live if it's avoidable. There are none contact measures available to indicate voltage and anyone sticking both hands inside a piece of live apparatus even with the fingerproof terminals in current use would need a serious amount of reprogramming.

The other point you may care to consider is that many " professional" meters The Flukes I used included, do not have a fuse for the higher current ranges. Although different sockets and interlocks are available, this does not allow for operator error. I'm not sure what would make the most effective fuse at that point, the shunt or the test leads.

On a final note, I consider one of the most serious ommissions from any meter now is the crock clip. I never ever did work two handed and do not feel comfortable doing so now, it seems strange however with todays safety culture you are forced into chinese restaurant mode to measure aross a couple of terminals.

On a final note do you actually connect equipment up to this phenomenally unstable supply the Electricity board provides?

I find it amazing that entire streets are not going down due to these "transients".

Do you sell extension sockets or UPS for a living BTW?

AB

[orion.osiris]

continue to study what's on the market. In the mean time, to replace my old White Gold meter from Maplin, I popped into my local Maplin store (better the devil you know) and bought one of these by UNI-T. They're a chinese out fit, but they make digital storage scopes so should know what they're doing :

c-interface-46458

Thanks for the heads up. I will whip the lid off when it arrives and will b e having serious words with Maplin if it turns out so.

[dom]

l continue to study what's on the market. In the mean time, to replace my o ld White Gold meter from Maplin, I popped into my local Maplin store (bette r the devil you know) and bought one of these by UNI-T. They're a chinese o utfit, but they make digital storage scopes so should know what they're doi ng:

-pc-interface-46458

be having serious words with Maplin if it turns out so.

I own a UNI-T multitester (

) and for t he price I'm quite happy with it. In all the ways I've been able to test it , it seems to perform to it's stated spec. But I'm using it either as an in sulation tester or low-ohm meter. That has safety implications, but less so than probing into a live high-energy system.

Maybe they've found a way to make your meter Class III without requiring HR C fuses. Realistically, Maplin isn't in a position to check every claim on every product they sell, and has to trust its suppliers.

I see both sides of the arguments advanced here. As John Rumm says, for ser ious work, it's a real safety concern. As others say, for very occasionally probing inside a CU - you would be phenomenally unlucky to come to grief.