How GasSafe men test electrical

[PEG]

Leave em' alone....due to a lack of bookings,the tribute band "Bad Manors",has been pursuing alternative careers.....

 

[mainline]

What he is doing can be done with a normal decent multi meter. But I suppose it is for men who have little idea of electrics.

Interesting, can you explain how to do an earth loop impedance test using a multimeter ? I'm wondering just in case my MFT dies.
Thanks in advance

 

[davesparks]

Interesting, can you explain how to do an earth loop impedance test using a multimeter ? I'm wondering just in case my MFT dies.
Thanks in advance

I guess it could be done with two multimeters and a mildly dodgy setup.

Connect a load between line and earth, take a few readings and calculate the loop impedance!

 

[mainline]

I guess it could be done with two multimeters and a mildly dodgy setup.

Connect a load between line and earth, take a few readings and calculate the loop impedance!

Why 2 multimeters

I have a feeling that when I put my multimeter on the low ohms range and put it across live and earth
(1) the RCD will trip
(2) the meter will go bang

 

[Jim_e_Jib]

Why 2 multimeters

I have a feeling that when I put my multimeter on the low ohms range and put it across live and earth
(1) the RCD will trip
(2) the meter will go bang

Ohms is not the measurement you need - you wouldn't set your MFT to low ohms to get a loop impedance reading, you'd set it to loop impedance and let it calculate it.

What measurements could you calculate the loop impedance from?

 

[davesparks]

Why 2 multimeters

I have a feeling that when I put my multimeter on the low ohms range and put it across live and earth
(1) the RCD will trip
(2) the meter will go bang

One to measure current and the other to measure voltage at the same moment.

Yes if you were daft enough to do that it would trip, but that is not what I am suggesting.

Remember a loop impedance tester is just measuring current and voltage to calculate the impedance. Well technically if you break it down further it is probably going to be measuring 2 voltages and then calculating everything else from there.

 

[mainline]

One to measure current and the other to measure voltage at the same moment.

Yes if you were daft enough to do that it would trip, but that is not what I am suggesting.

Remember a loop impedance tester is just measuring current and voltage to calculate the impedance. Well technically if you break it down further it is probably going to be measuring 2 voltages and then calculating everything else from there.

Actually, the question was to John


Yes, I understand how it works, the question is HOW to do it using a multimeter.


The problem is to measure involves time. Within a very short time the meter measures voltage with a load and without a load and calculates from those readings the earth loop impedance.
Since measured to earth during the test it will raise the earth voltage towards line voltage, which means if the earth is not good it could have dangerous voltages on the earth. To reduce these dangers the meter measures in less than 40ms this also means it will not trip the RCD

 

[mainline]

Ohms is not the measurement you need - you wouldn't set your MFT to low ohms to get a loop impedance reading, you'd set it to loop impedance and let it calculate it.

What measurements could you calculate the loop impedance from?

Ohms is not the measurement you need - you wouldn't set your MFT to low ohms to get a loop impedance reading, you'd set it to loop impedance and let it calculate it.

What measurements could you calculate the loop impedance from?

I understand how it works Jim but the question was asked to john as he said it can be done with a multimeter I was interested How it could be done using just a multimeter

 

[Jim_e_Jib]

I understand how it works Jim but the question was asked to john as he said it can be done with a multimeter I was interested How it could be done using just a multimeter

So, something someone wrote two years ago has rattled you so much that you feel the need to try and make them look a fool? Is everything alright?

 

[mainline]

So, something someone wrote two years ago has rattled you so much that you feel the need to try and make them look a fool? Is everything alright?

My original reply was deleted, but I see your assumption that I'm out to make someone look a fool is left to stand.

Why would you be assuming that I'm trying to make someone look a fool ?

I didn't realize the post was that old.

I'm actually interested to see how you could measure earth loop impedance just using a multimeter.

 

[Jim_e_Jib]

My original reply was deleted, but I see your assumption that I'm out to make someone look a fool is left to stand.

Why would you be assuming that I'm trying to make someone look a fool ?

I didn't realize the post was that old.

I'm actually interested to see how you could measure earth loop impedance just using a multimeter.

Your original reply encouraged me to stalk another man on on the internet.

I'd be in violation of the condition of my parole if I did, so I'll pass on that thanks.

 

[briand]

and the next educational video will be......

how to construct your own boiler from scrap materials ( oh bugger British Gas have already done that)

I do love British Gas approach to electrical problems. On a site they questioned my calibrated Fluke meter as they said there was no neutral and were going to switch the client off for safety. The TV didn't seem to bother about the lack, and when they took their tester next door it said the same. I could not resist saying it must be the street. I did suggest they took their 2 "testers" and put them under their van wheels as they drove off!