Is it acceptable to enter low IR on MWC

[FreeLec]

When doing minor works on a circuit, which may take a very short time to complete and it requires a MWC the IR test between L-N and E may be zero due to other electronic items.
You can end up spending 10 times longer looking for and disconnecting them just to get a good IR reading.

The company I work for has a policy of entering the low reading with an explanation of why and then arranging extra time at another time and charging to diagnose and rectify, even if it just means tracing electronic items, disconnecting and re-testing.

This is acceptable to the establishments they are working for.

However, it does not seem correct to enter what is effectively a fault on a certificate that is supposed to show the circuit as tested and okay, just as with an EIC. It's not a EICR so I would have thought this wrong.

However, what other way of doing it is there short of saying to the customer that before any work is done the circuit has to be tested as to fitness and any faults rectified but it's done the other way round with this lot ending up with a fault on the MWC. Only when the fault is cleared (or found that it is just electronic items) is the MWC changed.
The one with the fault is still given to the client until the updated one is done.

There are times, though, when no one has gone back to re-test as the client has given no further instruction, so the client has ended up with a MWC with an IR fault.

Any thoughts?

 

[Octopus]

Define low reading.......

 

[FreeLec]

Anything under 1 meg but usually 0.01 or 0.00 as even one piece of equipment can cause that

 

[Andy78]

Are the correct procedures for testing of IR with electronic equipment connected followed ?

 

[FreeLec]

L-N connected together. N removed from N bar. 250V, not 500V.

 

[Lucien Nunes]

L-N connected together. N removed from N bar. 250V, not 500V.

and

0.01 or 0.00 as even one piece of equipment can cause that

...do not tally. I don't know of any normal piece of equipment that has just tens of kΩ or lower IR to earth. What sort of equipment are we talking about here? The only time I see this kind of result on a 250V test is where US-spec 120V equipment containing surge arrestors designed for 120V supplies is supplied via an auto-transformer from 230V. Because the transformer passes the DC test voltage direct to the load, the VDRs can start to conduct and throw the reading off.

What specifics can you think of on these sites that would be causing this?

 

[FreeLec]

Have to go out. I will respond in about an hour or two.

 

[Octopus]

Do your employers charge for the 2nd visit?

 

[FreeLec]

Yes.
They charge for the time taken to investigate whatever the problem may be. If it's a matter or taking something out of circuit to re-test or a fault that needs rectifying it is chargeable. If the fault is major then that may even involve arranging a further visit to allow time to rectify. All chargeable.
This is something that is arranged with the clients as they are educational establishments where disruption can be an issue.

 

[Pete999]

When doing minor works on a circuit, which may take a very short time to complete and it requires a MWC the IR test between L-N and E may be zero due to other electronic items.
You can end up spending 10 times longer looking for and disconnecting them just to get a good IR reading.

The company I work for has a policy of entering the low reading with an explanation of why and then arranging extra time at another time and charging to diagnose and rectify, even if it just means tracing electronic items, disconnecting and re-testing.

This is acceptable to the establishments they are working for.

However, it does not seem correct to enter what is effectively a fault on a certificate that is supposed to show the circuit as tested and okay, just as with an EIC. It's not a EICR so I would have thought this wrong.

However, what other way of doing it is there short of saying to the customer that before any work is done the circuit has to be tested as to fitness and any faults rectified but it's done the other way round with this lot ending up with a fault on the MWC. Only when the fault is cleared (or found that it is just electronic items) is the MWC changed.
The one with the fault is still given to the client until the updated one is done.

There are times, though, when no one has gone back to re-test as the client has given no further instruction, so the client has ended up with a MWC with an IR fault.

Any thoughts?

Link L&N and test IR to Earth and note on the cert, sorry forgot set test voltages to 250v

 

[FreeLec]

Pete999

Look at comments 4 and 5 above.

 

[Pete999]

Pete999

Look at comments 4 and 5 above.

Point taken must read the whole thread

 

[FreeLec]

LUCIEN NUNES

Sorry! Completely forgot to look at your comment when I got back as someone else left one and I got distracted by that.

I don't understand why you would think that the two comments would not tally. Some electronic equipment have functional earths so there will be a current flow, all be it very small, between L-N and earth. One well known example right at the start of the circuit is an RCBO with an earth tail. Even the simplest circuit with nothing connected, e.g: radial to one socket outlet with nothing plugged in, will show 0.01 Mohm between L-N and E unless you either disconnect the earth tail from the earth bar or you remove both L and N from the RCBO.

 

[davesparks]

Why is this only becoming apparent at the testing stage?
Any faults in the existing should be identified before you start work, not after.

 

[Octopus]

Hum.... so you quote for a job, don't isolate everything, issue a cert stating extra investigation is required, then go back for a 2nd chargeable visit.

Sounds like a dodgy money making exercise to me.