Discuss Insulation resistance test? how does it work in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

Reaction score
24
Trying to understand how the insulation resistance test works
this is how I think it works, i maybe right or maybe wrong?????????

bascially, your shorting circuiting neutrel and phase.
Sending 500v down the cable (If no voltage no current)
So the tester sends out a current, then reads the return Current and calculates the leakage

then using ohms law, calculates the resistance

and this is a DC test?


is this right?

regards luke
 
luke,

erm....basically yeah:rolleyes:

Its applying a DC voltage accross two points and measuring the resistance to current flow between them

the tester doesnt 'send out' a current. Current is drawn by whatever circuit the voltage is applied to

and you are not short circuiting neutral and phase. If you mean joining the neutral and phase together at the tails and checking between them and earth, then that is just one method of carrying out an IR test:)
 
Luke, no basically!

voltage (potential difference) has to have 2 points (for there to be a difference in potential!!)

if testing at 500V (for example) then 500V DC is applied to the end of the probes (i meen 500v between the two probes) and the meter will register how much resistance to current flow it encounters:)
 
oh but i will Luke, i love questions

ok, classic 2391 question

if testing between the input and output phases of a selv circuit, what is the minimum insualtion resistance value (16th edition answers please)

and 10 circuits, each having resistance phase to earth of 10megohm, what insualtion resistance would be measured at the tails?

off you go then.....:)
 
Well done Gally;)

come on Ian i tought you knew the book!!!:p:p:p:p:p:p:p:D:eek:

Yes if it was SELV it would be 0.25V,

but i asked about checking between the input and output phases of a SELV circuit. In this case you work on the highest votage involved, which is the 230V supply.

So you would test at 500v with 0.5M as the minimum

I can find the reg number if you wish, but aint got the book in front of me...........

back of the class, hands on head, no talking.
 
oh i got plenty Luke,

did you work out the circuits in parallel one? thats very typical as well


ok, another one

a circuit wired in 4mm twin and earth is 10m long. Insulation resistance between live conductors is 10Mohm. R1+R2 is 0.75ohms. If the circuit was to double in length, what be the effect on insualtion resistance value and R1+R2 reading.

and another:

Ring main is wired in 2.5/1.5mm twin and earth. rn is measured at 1 ohm.

what is

r1 value
r2 value
R1+R2 value

and explain simply how you measure the R1+R2 value.


ok, off you go........:D:D:D
 
Luke, no basically!

voltage (potential difference) has to have 2 points (for there to be a difference in potential!!)

if testing at 500V (for example) then 500V DC is applied to the end of the probes (i meen 500v between the two probes) and the meter will register how much resistance to current flow it encounters:)

I don't understand how an IR tester running on 6 AA batteries can shoot 500v??
 
I don't understand how an IR tester running on 6 AA batteries can shoot 500v??

Magic!

Or electronics.

Like 12V to 230V inverters, LED torches that run on one AA cell, etc. One way is run an oscillator off the DC supply, to make AC. Then through a transformer to boost the voltage. Then rectify the output if you need DC again.

You have won todays thread resurrection prize. :)
 
Magic!

Or electronics.

Like 12V to 230V inverters, LED torches that run on one AA cell, etc. One way is run an oscillator off the DC supply, to make AC. Then through a transformer to boost the voltage. Then rectify the output if you need DC again.

You have won todays thread resurrection prize. :)

That's just magic !!
 
yep. as said. just think of a simple inverter, 12V dc in and 240Vac out. all due to the magic of electrickery ( with some electronicals thrown in)
 

Reply to Insulation resistance test? how does it work in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc
This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock