Multimeter

That's resolution, not necessarily accuracy. Depending on the full scale of the lowest range, the readings for very small currents could be widely inaccurate. The specification would be something like +/-1% + 5 digits Assuming a 4 digit display and a 1ma full scale on the lowest range

Where the resolution could be useful is when comparing two like items. One item could be passing 0.017mA and the other 0.019mA. You could confidentially say that item 2 was passing more current without actually knowing the absolute true value.

On analogue meters you can also have parallax viewing errors. That's why "quality" analogue meters of the past used to have a mirrors embedded in the scale.

Cheers!

It also misses the point. Even if you used a 5mA range to measure that

Yes, though I never found them in practice to add any accuracy.

NT

Not if you're going to use it across the mains:

If needing current measurement on AC, then its often worth considering a clamp meter - lets you measure mains current more easily without needing to break into the circuit.

We're getting into how many UKdiyers does it take to change a lightbulb territory here

CPC have just been having a "sale" on clamp meters

Are they any good - or accurate - for measuring low currents? I have one, and I can't say I've ever used it 'for real' (other than checking see if it worked by clamping it on the single cable tails connecting the incoming mains to the electricity meter).

Don't forget that, when making mains (or any) measurements, you mustn't have both the go and return conductors inside the jaws of the clamp. For convenience, you really need to make special test extension lead, with individual live, neutral and earth conductors (ie not enclosed together inside the sheath of the mains cable).

Well thats better then the 5 quid Maplin jobbie which is a waste of 5 quid IMHO. I've have a look round for a s/hand Fluke they sometimes go for not a great deal more than that. Also a decent set of insulated probes is a must...

In message , Ian Jackson writes

Real men use them as prince alberts

fine if the conductors are separate. Not a lot of use on twin&E

That looks more than adequate, and with safe probes. Now to the question of how to use it: "Getting the Most from Your Multimeter" by R.A. Penfold , published by Babani ages ago and probably still at your local library isn't a bad place to start, though there are surely more modern articles published on the www?

For the OP Youtube could be his friend. There will be everything from the unhelpful 10 minute video of unpacking the jiffy bag the DMM came in to basic and more detailed tutorials. As with all things on the net there will also be some crap and some people demonstrating something they know little about. The OP will need to view more than one video to sort the wheat from the chaff.

Perhaps start with

Maybe follow on with an 30/60 minutes of tutorial

Dave Plowman (News) wrote on Aug 25, 2012:

The model I have doesn't have current ranges - just AC/DC voltage plus resistance and capacitance. That's all I normally need - if I ever do want to measure current I use an even older Avo 8.

I wonder what they measure then.

So you've done that as well as me?

Depends on how low... for most mains appliances they are adequate, unless dealing with tiny loads. However there is a trick you can use here...

Indeed - and here is where the trick can come in handy. For measuring low currents, loop one of the live conductors through the clamp more than once. Its relatively easy to bundle up say ten turns of conductor and then clamp round the side of the bunch. That will scale your reading to ten times the actual current.

It just requires a bit of lateral thought... say clamping round the conductors as they emerge from the MCB in the CU, or if the load conditions for the rest of the house are stable, then clamping round a meter tail, and looking at the difference in reading with the circuit / appliance of interest on and off.