Make sure you are very familiar with your meter and always test for live before proving dead, ie connect meter and read 230 volts then switch off circuit breaker and note voltage is no longer present. Also be aware that neutrals can also be live and present a risk.
Digital Multimeter Recommendation Required
- Thread starter Bristol_Rob
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Calibration is likely to cost £20 to £50 depending on what the device is.
It's necessary if you are using a meter professionally and submitting test readings to a client or building control.
For an amateur, I very much doubt it.
The best value way is to cross check your meter against another if the opportunity crops up. Either a friends or a second one of your own that might not cost much more than a single calibration fee.
Folk who do much electrical work may find a second different meter handy.
e.g.
Clamp meters are incredibly useful for measuring current without having to wire the meter into the circuit.
Specialist "leakage clamps" are sensitive enough to measure the small currents that trip an RCD and are useful in fault finding modern domestic wiring. "Nuisance trips" are pretty common now that RCD use is widespread.
Electronics nerds might need a (typically more expensive) 5 digit high resolution meter and a super sensitive micro amp current range for work on circuit boards.
All of these will also, usually, have some standard volt /amp / ohm ranges so they can be used to sanity check each other.
Incidentally - you can get current clamps as an accessory that plug into any multi meter. The accessory style aren't sensitive enough for measuring RCD leakage currents but for measuring the current being drawn by a machine or motor, say, they are handy. You just clip the clamp around ONE of the live or the neutral wires.
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pe2dave
Established Member
Big difference, home user to professional?
The biggest issues we found with cheap meters was that they didn’t comply with creep distances on the high voltage side. The means that it could ark over to the low voltage side or anything else. Test leads were particularly carp. However, just to put this to context, the most sophisticated multimeter test leads at the time, fully compliant calibrated and CE tested cost less than £1 to make. So it’s not a cost issue just an ignorance issue. The hyped up prices these days make me smile, but it’s good for the shareholders.
The majority of the products I used to make are still in the catalogue.
The majority of the products I used to make are still in the catalogue.
It's about context, that's all.
If you are in an electronics design lab developing circuits, you are investing serious money. Paying someone to ensure "your tools are always sharp" is a no brainer. In that context it's a small cost to eliminate a small risk which might have expensive consequences - recall and replacement of £millions worth of circuit boards because tolerances mean a random half percent are out of spec...
I once worked for a firm who's highest volume circuit boards each sold over a million units at £100 apiece. You don't want to get those designs wrong.
If you are an employer, then you have a duty of care to your people. That small risk that an inaccurate meter causes someone harm could be very costly in may ways. Harm may not mean an electrical shock, it may mean that a low voltage control signal in a machine safety system doesn't work correctly and someone gets crushed or amputated. You minimise these risks by a combination of the right people with training and skills, procedures and tools. Calibrated instruments would matter here too. An hey, you might be maintaining a nuclear power station
I have eight different meters (OK, two too many...) - Fluke, Keysight and Megger. Seven have only ever been for my own hobbies and have never been calibrated since the factory. They agree with each other within a small margin and have done for decades. Good meters are very stable.
The last one is the only one I've every had calibrated because I used it for a task where it was necessary to provide the meter serial number and a copy of the calibration certificate along with the measurements taken with it.
No one has mentioned the need to null the test leads when measuring resistance to exclude the test lead resistances from the measurement !
