amp meter wanted

[AstonHill]

Anyone know of a shop that sells them please. went into "Yes Electrics" and did not even know what an amp was. (bit like Euro car Parts)
Not interested in scam from ebay and Amazon (BTW I have a CCJ against ebay!) Just want a real shop with real quality
I am sure they do exist as I saw them many moons ago as amp dials on the dash board of popular cars

 

[Bodgedbuild]

I have to ask, what do you need an amp meter for? Clearly you want it for a car but they are of little to no use these days and alternator outputs are extremely high which makes it difficult to be able to wire one in. To give you an example, my car is a BMW 320d and it's alternator is 180 amps. To run that sort of current through cables to and from the dashboard is impractical (due to cable size) and the losses in the cable and the internal shunt in the Amp meter would be problematic to say the least. If, however, you want to fit one to an old car with a dynamo that charges at 10 to 20 amps fitting one will be easily do-able and just searching for a Smiths Ammeter will prove fruitful with possibly this place as a suitable supplier?
https://thegaugeshop.com/SMITHS-AMMETER

 

[bernardgreen]

To run that sort of current through cables to and from the dashboard is impractical

The shunt is fitted close the battery and the voltage created by the current flowing through the shunt is taken to a voltmeter on the dashboard by a pair of small wires. Although measuring volts the meter is calibrated in Amps.

 

[ericmark]

In the main the ammeter is a volt meter measuring the volts across a shunt, in the old days the CAV 208 alternator had a shunt between the alternator and battery to control the alternator output with the 440 regulator between M1 and M2 terminals, these were one of very few alternators to have current control. Normally only found on buses and coaches, designed to keep the lights powered while engine ticking over.

I think Durite still make an ammeter but CAV and Lucas were part of British Leyland so when they went so did the major British auto electric manufacturers. Ring and Durite are still going and Stirling is big on the canal boat scene. So this is the type of thing we see today, cost over £100 made by Sterling Power and likely can be found in boat chandlers designed for the likes of narrow boats.

Today I use my clamp on when required, the cheapest clamp on to measure DC is around £35 from internet, but more like £100 from an electrical whole sale output, as in the main electricians need them calibrated, and cheaper models you can't get calibrated.

These came in 30 and 60 amp versions, the square version seems to have gone, the standard automotive test set

is still made by Durite, sure you could order one from any auto electrical outlet, the modern one is rather expensive, and as an auto electrician one needs both amps and volts at the same time, so the old one was better, but I now use

And sorry unlikely to find one except on the internet, at £35 so much cheaper that screwfix price £96 for cheapest DC ammeter.

 

[AstonHill]

I have to ask, what do you need an amp meter for? Clearly you want it for a car but they are of little to no use these days and alternator outputs are extremely high which makes it difficult to be able to wire one in. To give you an example, my car is a BMW 320d and it's alternator is 180 amps. To run that sort of current through cables to and from the dashboard is impractical (due to cable size) and the losses in the cable and the internal shunt in the Amp meter would be problematic to say the least. If, however, you want to fit one to an old car with a dynamo that charges at 10 to 20 amps fitting one will be easily do-able and just searching for a Smiths Ammeter will prove fruitful with possibly this place as a suitable supplier?
https://thegaugeshop.com/SMITHS-AMMETER

No this is not for a car, its for something ells
But that meter you listed is 80 quid!
180 amps from your car alternator! you sure?

 

[AstonHill]

The shunt is fitted close the battery and the voltage created by the current flowing through the shunt is taken to a voltmeter on the dashboard by a pair of small wires. Although measuring volts the meter is calibrated in Amps.

Surly that will depend on the cars make model est est to make such a presumption that one size fits all!

So tell me; how dose it messuring volts dose it calibrate at amps?

 

[AstonHill]

I think Durite still make an ammeter but CAV and Lucas were part of British Leyland so when they went so did the major British auto electric manufacturers. Ring and Durite are still going and Stirling is big on the canal boat scene. So this View attachment 307595View attachment 307596 is the type of thing we see today, cost over £100 made by Sterling Power and likely can be found in boat chandlers designed for the likes of narrow boats.

Yes that is the kind of basic thing I am after, infact I would rather an analong meter then a digital one. But at that money; no chance!

Today I use my clamp on when required, the cheapest clamp on to measure DC is around £35 from internet, but more like £100 from an electrical whole sale output, as in the main electricians need them calibrated, and cheaper models you can't get calibrated.

What do they do to it to calibrate it? what differance dose it make?

And sorry unlikely to find one except on the internet, at £35 so much cheaper that screwfix price £96 for cheapest DC ammeter.

I have had legal issues with screw fix that will more then likely end up in a CCJ soon (just like ebay did!)
And there web pages no longer load for me anyway. So I am happy to go to Tool Station next door to get what I want. Sadly they dont have or know what an amp meter is

Something that has been around in popular domestic consumption for so long and now its hens teeth at silly money"i don't believe it"

 

[bernardgreen]

Surly that will depend on the cars make model est est to make such a presumption that one size fits all!

No such presumption has been made.

 

[ebee]

Surly that will depend on the cars make model est est to make such a presumption that one size fits all!

So tell me; how dose it messuring volts dose it calibrate at amps?

If you run current thru a resistance/impedence (albiet a very small one) then if you measure the voltage across that resistance/impedance you can manually or automatically calculate the current.

Example, if you run the current thru a resistance/impedance of 0.1 ohms you can measure the voltage and therefore calculate the current and the 0.1 ohms when compared to other resistances in the circuit wiring will not really much affect the readings in many circuits.

Actually in a similar way, if we use our meters to measure our earth electrode resistance we send a known current from one electrode to another and measure the voltage at an intermediate electrode in order to determine the resistance to earth of the electrode under test, we might do this test if no mains voltage is present.

With Volts, Amps and Ohms, if we know two of those values we can calculate the missing value

 

[ericmark]

What do they do to it to calibrate it? what differance dose it make?

I have issues with calibration houses, had a bad experience, and personally all I do is compare two devices and if they both read the same, that's good enough, but I think scheme member electricians need to get test gear calibrated with a certificate issued to say it has been done. It is just part of the paper trail they need to generate.

I personally want to know within a week if a meter has gone faulty, if the pass mark is 1.38 ohms and I have passes 5 homes then find my meter has gone faulty, and is showing lower than it should to return to 5 homes is not so bad, but if I have done 40 homes, then that's enough to bankrupt an electrician having to return to do so many, so before I retired I would test a socket in my own house which had been tested many times before to ensure the meter was still OK. Having a meter tested once a year is not really good enough.

GEC large steam turbines when I worked for them went crazy on calibration, even the crimp pliers were calibrated.

So tell me; how dose it messuring volts dose it calibrate at amps?

I showed this picture

the current goes through the large terminals and at the top the small plug has the very small voltage that goes to the meter, the old CAV used the same shunt to work ammeter and alternator control The metal lump shown below turned current into voltage, it could be trimmed with a hack saw.

 

[ebee]

"I personally want to know within a week if a meter has gone faulty, if the pass mark is 1.38 ohms and I have passes 5 homes then find my meter has gone faulty, and is showing lower than it should to return to 5 homes is not so bad, but if I have done 40 homes, then that's enough to bankrupt an electrician having to return to do so many, so before I retired I would test a socket in my own house which had been tested many times before to ensure the meter was still OK. Having a meter tested once a year is not really good enough."

Agreed.

In fact my own I sent away once a year (as required by my scheme) for cal but check it myself with my own set up every week-ish and I let a couple of others cross-ref theirs too every few weeks. Therefore any drift on any meter would be spotted pretty quick and any drift on the test set ups ditto.

If one firm has one meter (or 5) they all use and its paid for by the firm and gets thrown about in vans then one a week would not be often enough but one electrician using it solely and they`d paid for it themselves then sending away every three years might be often enough.
Actually, some wholesalers run a testing day once or twice a year, take your meters in one day and call back for it the next day and at a discounted price.

 

[Jackrae]

Those Lucas style ammeters were invariably moving-iron rather than moving-coil types and had only one or two turns of heavy copper driving a magnetic pointer. As such the full measured current has to flow through the meter. So not really practical for the modern vehicles need. Apart from that £80, for a recon unit takes the biscuit.

 

[ericmark]

I started at a new firm to do in the inspecting and testing as HSE had picked them up, so likely my work would be scrutinised. I thought computer records was the way to go, so step one was a computer program for the PAT testing.

When it arrived it wanted the reading, but the old PAT tester seems never used, but had just been sent away for the certificate only had pass/fail lights.

Answer from software firm was easy, look at what the pass was on the certificate and enter that. However it was not recorded, sent software back, used excel instead so once I had pass level a word change pass1 to x ohms could be used, and the people it went away to were contacted, seems sub contracted, but no problem it was a traceable record.

It went on for months, in the end they were told no more business until I get details, and we spent around 20k a month, so at last things moved, but the calibration house asked for PAT tester back, which we did, then they said it was set to old standards, and could not be got to the new standards, this meant 4 months PAT testing was useless.

We got a new top of range Robin tester at a discount price, and the supplier sent a tester to do all the office equipment, but since then never trusted calabration houses.

 

[Harry Bloomfield]

The shunt is fitted close the battery and the voltage created by the current flowing through the shunt is taken to a voltmeter on the dashboard by a pair of small wires. Although measuring volts the meter is calibrated in Amps.

In fact the 'shunt', need only be the resistance of the existing cabling.

 

[bernardgreen]

In fact the 'shunt', need only be the resistance of the existing cabling.

In deed,

Could be achieved by a pair of "spikes" into the cable from the battery. Not very accurate but then in those days it was better than nothing