Earth Loop Impedance Testing
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Asking questions suggests there is knowledge they are lacking. They consider asking questions puts their ability in doubt in the eyes of their clients. Hence they will not ask but instead try and fudge it.
So my next question is can loop impedance test be done if there are other loads on the xtrm
Yes it can be done.
The loads already there create a voltage drop due to current through the impedance. Adding a test load increases the current and hence the voltage drop increases. The increase in volt drop while the test load is connected along with the current the test load takes are used in the equation
Z ( loop impedance ) = voltage drop increase / test load current
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Correction, for the record all of this should of been quoted
"The real problem that I see is when qualified/professional people don't ask questions, this applies to trades as much as to engineers. Many of them pretend to know what they are doing. The longer that this goes on for the harder it is to admit that they don't know something and as a consequence chances of an accident increases. I would far rather that people like this look for assitance ask questions and learn. I have also found that by answering questions I have learnt from it too.
When I was an apprentice (over 20 years ago) when many apprentices did "day release". One day a week they were sent to college. Frequently instructors did not even turn up, and of the ones that did some were of little use. I remember an entire class failed thier exams, shortly afterwards day release was abandoned for good. Remember at the time an electrician could fail the exams and still qualify. Many of these electricians are still around today and some of them may never have been involved in testing."
"The real problem that I see is when qualified/professional people don't ask questions, this applies to trades as much as to engineers. Many of them pretend to know what they are doing. The longer that this goes on for the harder it is to admit that they don't know something and as a consequence chances of an accident increases. I would far rather that people like this look for assitance ask questions and learn. I have also found that by answering questions I have learnt from it too.
When I was an apprentice (over 20 years ago) when many apprentices did "day release". One day a week they were sent to college. Frequently instructors did not even turn up, and of the ones that did some were of little use. I remember an entire class failed thier exams, shortly afterwards day release was abandoned for good. Remember at the time an electrician could fail the exams and still qualify. Many of these electricians are still around today and some of them may never have been involved in testing."
Next question
Method for determining ZS can be done either by tester or
Adding the the results ofZe to R1+R2 at the end of the circuit
Where is the location of R1,R2
One of them is the most distance point
Is this R1 ? Where's is the R2? Location?
Method for determining ZS can be done either by tester or
Adding the the results ofZe to R1+R2 at the end of the circuit
Where is the location of R1,R2
One of them is the most distance point
Is this R1 ? Where's is the R2? Location?
It's a common arrangement where the HV neutral is distributed. The idea in general seems to be to bond as much together as possible to keep the resistance to earth as low as possible at all points on the neutral system. As I mentioned earlier, it's not seen around my area of northern California since the majority of local distribution is 12kV delta with no distributed neutral, so all transformer primaries are phase-to-phase connections, but it is very much the norm in other parts of the country.
Again, it's not uncommon to see multiple voltages running parallel on the same poles. You can find places with three different HV voltages (in decreasing order of voltage from top to bottom) then LV below those and telephone/cable TV at the bottom.
Ah, I was wondering about the Irish flag! Although I'm living in the U.S. now I'm British born and raised, so quite familiar with U.K. systems.
R1 is the resistance of the live/line/hot conductor
R2 is the resistance of the protective earth/ground conductor
I was thinking it was that,out and back ,makes perfect sense
So adding the Ze which is out and back using line and neutral at the line side of the meter socket for example to the xtrm to the internal line and neutral at the load side of the meter to the furthest point will give will give me Zs ? What does the s stand for in the Zs?and Ze is just the external measurement only e meaning external?
So the real big question is why don't we loop test here in the USA. Some have said ,it's because it not in the NEC and the instrument manufactures are reluctant to launch the units here for that reason.There is no code that says we have use a multi meters , clamp meters to test voltage or amperage either. It would seem like a really good idea. Many time I have customers that have fires , floods . It would be an excellent way in my opinion to trouble GFCI problems .loop test to located the affected areas.To narrow it down we then then could use a megger to find the melted wires. The loop test would be a terrific trouble shooting tool for finding high impedance ,loose connection and to prevent fires , also takes us of the hook in a court of law that our work was tested at the time of installation . If a plumber is required pressure test his pipes for leaks we should be doing some basic test of our wiring to protect our skin and the customers . In reality arc faultsand GFCI effective in some ways only mimick the real problems associated with faulty wiring
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UK law is also rather vague as to what needs testing. We have two laws the electricity as work act and Part P the latter changes between Principalities and countries within the UK. However the rule book which is not law is universal our BS7671 lays out what we should do with low voltage (below 1kV) and is regarded as being law by many. Because many electricians are members of a scheme to enable them to self certify domestic work the BS7671 is law to them as they agree to abide to it as a condition of their scheme membership. These electricians have to have books and test gear to hand where in commercial situations there is no such requirement.
Domestic electrical systems in UK were poorly maintained and the electricians working on domestic were called house bashers and considered lowest of the low. The Part P building regulation changed this and now domestic electricians in the main are on par with commercial and often far better informed about regulations. However it has also raised a barrier between domestic and commercial I would flit between the two in many of my jobs but today cost of scheme membership and safety cards means many have to decide which to do.
In commercial it was common to keep records and seeing a loop impedance which had deteriorated rings alarm bells and I have found many a loose earth as a result. However in domestic the electric installation condition report only seems to be done with rented property I know Scotland was considering making it mandatory but not sure if it's in yet.
The loop test can highlight pour earth and also calculate volt drop and for years I would measure and record but never really consider all the information which could be extracted from the readings. Mainly as before the PDA it was a lot of maths to work it all out. However today it is easy to enter readings into excel or java script spread sheets and at a glance see errors with volt drop.
What worries me if I don't check then some one may check in the future and a claim made against me using my own test results. When I tried using my new smart phone and found java script did not run it resulted in having to take lap top onto jobs to get the results. How long people can wait before raising faults to ones attention I don't know but since a PIR / EICR was to be done every 10 years it is reasonable to expect faults to be raised 10 years after the re-wire when the first test is made. I don't want today's work coming back in 10 years time to haunt me. So I am very careful to ensure it's A1 but it also means retaining records for 10 years.
On one job I sent a PAT tester for calibration it was an old unit but had never been used I was employed to get records up to date. I sent for software to record on a computer and this software required the readings to be entered but tester just had a go/no go light. So I enquired what to do and answer was read the calibration certificate and enter the pass figure on the software. However there were no figures recorded on the certificate but since it was a traceable record there would be no problem I just needed to ask. In the mean time I used excel and wrote "pass figure" which I knew I could easy change to actual reading and sent software back. The tester it seems was not tested by the firm I had given it to but it had been sub contracted and it took some time. In fact after 6 months I threatened to stop trading with them unless it was sorted. I was then asked to re-submit the PAT tester it seems they could not find the traceable record. On return it transpired it could not be set to new standard it was passing items with too low of a insulation resistance. Clearly the calibration certificate should never have been issued. I now had 6 months of unless PAT testing. We got a very good deal on the new PAT tester because of the error but I am telling story to point out calibration certificates are not worth the paper they are written on and what every instrument we use errors may exist.
Domestic electrical systems in UK were poorly maintained and the electricians working on domestic were called house bashers and considered lowest of the low. The Part P building regulation changed this and now domestic electricians in the main are on par with commercial and often far better informed about regulations. However it has also raised a barrier between domestic and commercial I would flit between the two in many of my jobs but today cost of scheme membership and safety cards means many have to decide which to do.
In commercial it was common to keep records and seeing a loop impedance which had deteriorated rings alarm bells and I have found many a loose earth as a result. However in domestic the electric installation condition report only seems to be done with rented property I know Scotland was considering making it mandatory but not sure if it's in yet.
The loop test can highlight pour earth and also calculate volt drop and for years I would measure and record but never really consider all the information which could be extracted from the readings. Mainly as before the PDA it was a lot of maths to work it all out. However today it is easy to enter readings into excel or java script spread sheets and at a glance see errors with volt drop.
What worries me if I don't check then some one may check in the future and a claim made against me using my own test results. When I tried using my new smart phone and found java script did not run it resulted in having to take lap top onto jobs to get the results. How long people can wait before raising faults to ones attention I don't know but since a PIR / EICR was to be done every 10 years it is reasonable to expect faults to be raised 10 years after the re-wire when the first test is made. I don't want today's work coming back in 10 years time to haunt me. So I am very careful to ensure it's A1 but it also means retaining records for 10 years.
On one job I sent a PAT tester for calibration it was an old unit but had never been used I was employed to get records up to date. I sent for software to record on a computer and this software required the readings to be entered but tester just had a go/no go light. So I enquired what to do and answer was read the calibration certificate and enter the pass figure on the software. However there were no figures recorded on the certificate but since it was a traceable record there would be no problem I just needed to ask. In the mean time I used excel and wrote "pass figure" which I knew I could easy change to actual reading and sent software back. The tester it seems was not tested by the firm I had given it to but it had been sub contracted and it took some time. In fact after 6 months I threatened to stop trading with them unless it was sorted. I was then asked to re-submit the PAT tester it seems they could not find the traceable record. On return it transpired it could not be set to new standard it was passing items with too low of a insulation resistance. Clearly the calibration certificate should never have been issued. I now had 6 months of unless PAT testing. We got a very good deal on the new PAT tester because of the error but I am telling story to point out calibration certificates are not worth the paper they are written on and what every instrument we use errors may exist.
I know in Ireland there are electricians who spend a great deal of time doing cert for customers for sign offs on new projects , re wiring , remodeling and so on. Landlords and builders don't alway like the hassle and cost associated with testing. Electricians may find ways around keeping accurate records or keeping files for year down the road
This is a bigger problem here in the U.S.
We're everything and everyone
Want it passed today
This is a bigger problem here in the U.S.
We're everything and everyone
Want it passed today
I'm saying we should test. I'm all for safety in the industry. Perhaps there is a more efficient way to deal with paper work and a more secure way to keep track of records? I think the ideas of testing was presented here many years ago but was met with fierce objection for many of these reasons and the other previously stated. With the advancement meant in technology just in the last ten years alone would surely simplify the whole testing process
Ok with this but I'm
sure there's soft ware to plug in to determine the Ed
I have use this formula forhouse hold circuits to get an idea when my run get over 200' depending on the load and wire size
If I wanted find my voltage drop before I run the circuit I would use Ed=kIL/CSA
Or maybe there's another easier way?
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