Testing for IR

[SKY]

Hi Gents

Using a Megger 1553 tester how do you test for insulation resistance in lets say a ring main?

Also what readings should be attained?

Sorry for the basic question, I'm learning ahead of my training to gain a better understanding.

Thanks

Simon

 

[acat]

Set megger to 500v reading should be 299Mohms when set and connected press your yellow button.


Chris

 

[acat]

Forgot to add in your practicals if you have neons or anything else in the circuit that you cannot remove connect live and neutral to one clip and earth to the other clip that will give you a true reading.


Chris

 

[m4tty]

Hold red probe in left hand and green probe in right and press yellow test button. 250 tickles LOL ONLY JOKING MATE

You have to hold the yellow button down until the reading on the megger stops. HTH

 

[acat]

Hold red probe in left hand and green probe in right and press yellow test button. 250 tickles LOL ONLY JOKING MATE

You have to hold the yellow button down until the reading on the megger stops. HTH

Thats wicked but I like it


Chris

 

[SKY]

Do I test at the fuse board? red on live (mcb) and green on neutral bar then do the test?

What is the plug for with the megger?

 

[acat]

When you are doing an IR test you are testing the cable not the consumer unit so its onto the brown cable and cpc then blue cable and cpc or if neons etc then its brown and blu on one clip cpc on the other. Plug is used for Zs and RCD tests on ring main.


Chris

 

[SKY]

When you are doing an IR test you are testing the cable not the consumer unit so its onto the brown cable and cpc then blue cable and cpc or if neons etc then its brown and blu on one clip cpc on the other. Plug is used for Zs and RCD tests on ring main.


Chris

Fully Understood. Do you always test at 500v? what if there are alliances connected down the line could this test damage them?

 

[acat]

As you are training I would suspect that it will be 500V however we do test at 250V but best not to confuse you to much at this stage once you fully understand what you are doing and why then you can consider the rest.


Chris

 

[Jason Smith]

I have to explain this to my apprentice tomorrow so I will practice trying to give you a clear explanation tonight. - By the way, when there is something I dont understand I commit the facts to my brain, one day someone will say something that suddenly makes it fall into place, I am really ashamed of some of the things I wrote in my notes when I was training, so keep asking.
Here goes.
An IR test is to see if there is any electricity leaking between the three cables in a wire, and obviously it may cause a problem or three if there is. My 1652b reads 500 MO on perfect wires. 500, 000,000 ohms.
We get a faster response from the tester if we test at 500 volts. obviously, all appliances use 240 volts, so that is the reaon for disconnecting them, and the fact that appliances if connected will not give a true reading when doing an ir test. Simples isnt it. That means every light bulb, etc out.
Sometimes its not possible to disconnect everything, so what we do is join the line and neutral tgether, and test between these two wires and cpc only. because damageable appliances areconected wetest at 240 volts. Simples.
As your knowledge builds you will learn that if two wires are joined together no lctric will flow as the potentil is the same between them so you can enter into the argument as why dont we test at 500 then ?- but dont get sidetrackd enjoy your learning

 

[ezzzekiel]

guidence note 3 - which also has pretty pictures

 

[Golden_Boy]

I have to explain this to my apprentice tomorrow so I will practice trying to give you a clear explanation tonight. - By the way, when there is something I dont understand I commit the facts to my brain, one day someone will say something that suddenly makes it fall into place, I am really ashamed of some of the things I wrote in my notes when I was training, so keep asking.
Here goes.
An IR test is to see if there is any electricity leaking between the three cables in a wire, and obviously it may cause a problem or three if there is. My 1652b reads 500 MO on perfect wires. 500, 000,000 ohms.
We get a faster response from the tester if we test at 500 volts. obviously, all appliances use 240 volts, so that is the reaon for disconnecting them, and the fact that appliances if connected will not give a true reading when doing an ir test. Simples isnt it. That means every light bulb, etc out.
Sometimes its not possible to disconnect everything, so what we do is join the line and neutral tgether, and test between these two wires and cpc only. because damageable appliances areconected wetest at 240 volts. Simples.
As your knowledge builds you will learn that if two wires are joined together no lctric will flow as the potentil is the same between them so you can enter into the argument as why dont we test at 500 then ?- but dont get sidetrackd enjoy your learning

Can you explain wht 500 volts gives a faster response ( faster than what) ?

 

[Golden_Boy]

Can anyone shed any light on this please ?
I am wondering how test voltage has anything to do with test speed..
As far as I know resistance = voltage/current so where does time enter the equation?

 

[mogga]

FIRST THINGS FIRST Make sure your supply is ISOLATED