Won Seaward test gear on ebay for £35 - Bargain?

[eveares]

Hi all, the other day i won some second hand Seaward test meters for £35 on ebay.

Doubt they have been calibrated for a long time, but none the less is this a steal?

I got a insulation resistance tester (IRT-S), a RCD/RCCB tester (RCT-S) and a broken and non functioning earth loop tester (ELT-S) what I guess was damaged by prolonged high current or from fall damage.

Below are some Photos.

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• eveares
• 17 Jan 2015
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• eveares
• 17 Jan 2015
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• eveares
• 17 Jan 2015
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• eveares
• 17 Jan 2015
• 1

 

[ban-all-sheds]

Pretty good if calibration shows them OK. Shame the matching one is b*****ed.

Before you get them calibrated, make or buy a check-box in readiness.

Any thoughts on how you'll get the calibrations checked?

 

[bernardgreen]

but none the less is this a steal?

Hopefully not a stolen which could present a problem getting them and their serial numbers onto a valid calibration certificate.

 

[eveares]

but none the less is this a steal?

Not literally of course, I mean have I got them at a amazingly good price?

make or buy a check-box in readiness

As is a check list??

thoughts on how you'll get the calibrations checked

Not sure I will as the calibration will likely cost more than what I paid for them all (£35) and I won't be using them other than for my self.

I tested the IRT-S with the 10meg input impedance on my multimeter and it displayed 10.00 mega ohms so I guess it is not wildly out of calibration. As for the RCT-S, I got 28ms at 1x 30ma and 4ms at 5x 30ma.

Although I would like to, I also doubt it would be worth repairing the ELT-S. The LCD is just displaying garbage as shown by the photo.

 

[JohnW2]

make or buy a check-box in readiness

As is ["in"??] a check list??

No - a 'box' which produces several resistances (low and high) and voltages etc. with which you can periodically check to see if your test gear is producing correct answers. Engineering a method of checking loop impedance measurements is less straightforward (although doesn't matter to you at present, since that one is broken!), and, for most people, devising a way of checking the quantitative RCD tests (particularly trip times) probably essentially impossible.

Kind Regards, John

 

[ban-all-sheds]

Not sure I will as the calibration will likely cost more than what I paid for them all (£35) and I won't be using them other than for my self.

You must get them calibrated - no point having them if you don't know they work.

 

[ban-all-sheds]

Engineering a method of checking loop impedance measurements is less straightforward

The checkbox plugs into a non-RCD socket in your house, and itself has a socket which your tester plugs into, with a 1Ω resistor switchable into the earth path. It doesn't matter what your EFLI actually is, what matters is does it change by 1Ω with the resistor in circuit.

and, for most people, devising a way of checking the quantitative RCD tests (particularly trip times) probably essentially impossible.

The box also contains an RCD.

 

[JohnW2]

Engineering a method of checking loop impedance measurements is less straightforward

The checkbox plugs into a non-RCD socket in your house, and itself has a socket which your tester plugs into, with a 1Ω resistor switchable into the earth path. It doesn't matter what your EFLI actually is, what matters is does it change by 1Ω with the resistor in circuit.

Yes, you and I (and others) know that, and have discussed it before - and it does give a reasonable degree of reassurance that the meter is probably giving correct answers. However, I call that 'less straightforward' than simply presenting resistances and voltages to measure!

and, for most people, devising a way of checking the quantitative RCD tests (particularly trip times) probably essentially impossible.

The box also contains an RCD.

I'm not too sure how that helps one to determine whether one's meter is giving correct (quantitative) measurements of trip times. I guess that I must be missing something.

Kind Regards, John

 

[ban-all-sheds]

Yes, you and I (and others) know that, and have discussed it before. However, I call that 'less straightforward' than simply presenting resistances and voltages to measure!

Nobody who finds the concept too hard to grasp, or the provision of such a facility too hard to accomplish, should be going anywhere near electrical installation work.

I'm not too sure how that helps one to determine whether one's meter is giving correct (quantitative) measurements of trip times. I guess that I must be missing something.

Because you've just had it calibrated, so when you get it back you can assume it is giving correct measurements, and at that point you start logging what it registers for your test RCD.

 

[JohnW2]

Because you've just had it calibrated, so when you get it back you can assume it is giving correct measurements, and at that point you start logging what it registers for your test RCD.

Fair enough - that will at least give reassurance that it hasn't systematically 'drifted' in calibration, but it's only looking at (roughly) one particular (probably 'normal') trip time. Do you only have one low and one very high resistance in your check box - and, if so, do they correspond with what would normally be regarded as 'normal' or 'abnormal' readings when the meter was used in anger?

Kind Regards, John

 

[eveares]

make or buy a check-box in readiness

I thought you meant something that I would call a decade resistance box, obviously not as simple resister type boxes do not plug into the mains.

The checkbox plugs into a non-RCD socket in your house

I don't have any non RCD protected sockets (or any circuits for that matter) and thus would have to either tap in before the RCD or use a isolating transformer to create a independent earth if suitable. Any other solution????

You must get them calibrated - no point having them if you don't know they work

As I said, I won't be using them for other people or regularly as a active electrician would. Calibration is not to see if they work, but to *tune* them to display the true and accurate value of what is being measured.

How much would calibration even cost, £50 per unit? - I have not got that much to spend unfortunately.

Also to calibrate the RCD, can't you compare the trip time displayed by the RCD tester against another time based measurement source such as an oscilloscope.

And how about self calibrating instruments if such things exist.[/quote]

 

[JohnW2]

I thought you meant something that I would call a decade resistance box, obviously not as simple resister type boxes do not plug into the mains.

Well, the resistance part of it doesn't have to be all that different from a 'decade resistance box', but it really just needs a few very low and a few very high resistors (alone or in combination). The low value ones are only used when testing the 'continuity' range of a meter, and that uses low voltage.

The checkbox plugs into a non-RCD socket in your house

I don't have any non RCD protected sockets (or any circuits for that matter) and thus would have to either tap in before the RCD or use a isolating transformer to create a independent earth if suitable. Any other solution????

If the meter your testing is capable of measuring an EFLI on the circuit (in either 'trip' or 'non-trip'mode), the method described by BAS can be used whether the circuit is RCD-protected or not.

You must get them calibrated - no point having them if you don't know they work

As I said, I won't be using them for other people or regularly as a active electrician would. Calibration is not to see if they work, but to *tune* them to display the true and accurate value of what is being measured.

That's true, and if the measurements are credible,it may suit your purpose. If you cannot afford formal calibration, you could try to find an electrician who would allow you to compare results with his/her and your meters, to make sure that they are at least similar.

Also to calibrate the RCD, can't you compare the trip time displayed by the RCD tester against another time based measurement source such as an oscilloscope.

You probably could (provided the scope wasn't being powered by the circuit you were testing/tripping ) - and that might even be how they calibrate them. However, a 'scope is not something which most electricians, and probably even fewer electrical DIYers, have!

And how about self calibrating instruments if such things exist.

I don't know whether such things exist (some certainly have a degree of 'self-testing') but, even if they did, they would have to be periodically calibrated against something independent, since even the 'self-calibration' could become faulty!

Kind Regards, John

 

[eveares]

However, a 'scope is not something which most electricians, and probably even fewer electrical DIYers, have!

Yea, I guess a digital storage oscilloscope is not that common to electricians.

I don't know whether such things exist

I was thinking of things like crystal ovens, resistors built in what are only used for calibration purposes and have a fine Temperature coefficient, etc...

Of course things can fail and drift out of spec for many reasons what can't be accounted or compensated for without calibration.

Also how quickly to test meters drift out of spec and become inaccrute in the real world?

 

[flameport]

I was thinking of things like crystal ovens, resistors built in what are only used for calibration purposes and have a fine Temperature coefficient, etc...

Too expensive and totally impractical for portable battery powered equipment.
Oven oscillators and the like use substantial amounts of power and have to be left on 24/7. If starting such an instrument from cold, it would typically have to left on for many hours before it can be used.

Also how quickly to test meters drift out of spec and become inaccrute in the real world?

From my experience - never.
If electronic measuring equipment goes wrong, it is usually in catastrophic ways which are immediately obvious.

Older meters had adjustable resistors etc. inside. New ones do not, it's all done in the firmware.

 

[JohnW2]

Also how quickly to test meters drift out of spec and become inaccrute in the real world?

As flameport has suggested, also in my (limited) experience - never (at least, to any significant extent). That's probably why it has been suggested to you, as someone will who will only be using to meters 'for yourself, that the ideal would probably be to get them calibrated just once, and then use some sort of 'check box' (or even repeated measurements on a non-changing installation) to reassure yourself that you are continuing get much the same readings as you were just after they had been calibrated.

Kind Regards, John