Discuss insulation resistane testing please help in the Periodic Inspection Reporting & Certification 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
20
Insulation resistance testing hasbeen carried out on a installation in a shower block and the followingresults obtained

live to live = 200m ohms
live to earth = 0.5m ohms

a. are these testresults are acceptable:
b. The actions to be taken should thetest results be unacceptable are:
 
Anything above 1mohm is acceptable, although I personally would like to see more than that.

Providing you have disconnected all sensitive equipment, then you have an issue with the insulation breaking down between live and earth. The section of cable at fault will need to be replaced.
 
There isn't much acceptable about either reading expressed in MilliOhms(m), I take it you mean MegOhms(M)!
 
Has as been said the result look poor live earth have you checked for neons if their is one then it will need to be isolatted so have a good look round see if their is one the retest with it isolatted
 
yes. because you are leaving a load with a finite resistance across L and N.
 
would neons the fact if they were neons that had not been discoonected cause this result to be too low?

Neons are usually connected across the L-N of the load side of the DP Isolating switch and register a value of around 0.2M Ohms, not L-E. If the DP Isolating switch is off then it shouldn't register at all.
 
Yes but a neon would not be across line and earth, unless its been installed by a cowboy.
Not sure of the effect of a neon, as IR tests are done with DC........

In any case, Paul.
This is obviously a college exam question, so you should be able to come up with an answer first. We could then give you some guidance. You'll not learn by just asking without making any effort.

*CLUE*
Have a look in BS7671 in teh section on IR testing and what the acceptable IR limits are. then you could come up with an informed answer.
 
so basically the actions the need to be taking is they needs investigating to find what is causing the results to be low. which something such as neons not disconnected before test. if we find what we think is causing it we need to disconnect it and do the test again until we get the reading over 1 mega ohms
 
Yes poor cable instulation damaged cable poor connections at switch or in the shower unit if its a electric type damp cable. loads of stuff but would need investigation as has been said are you new to testing it can take some getting your head a round hope I have helped.
 
SPD s can cause low line earth IR results and if they are class three can then be damaged by a 500V test since class three operate at 400V.
Make sure all sensitive equipment is removed from circuit before testing and (not according to the regs) test at 250v first, if you get a low result check the attached items again.

Neons tend to produce an IR value of about 0.1Mohms or 0.5Mohms Line to Neutral depending on type.
 
My most recent fault finding turned out to be a failed Fused Connection Unit.

Went down the route of "divide and conquer" found the area causing concern, disconnected terminations and results were great??? Connected accessories and tested again and fault was back. Removed accessories and tested between terminals of Fused Connection Unit and sure enough the fault was there. Replaced with new unit, retested continuity and IR and problem solved. :thumbsup
 

Reply to insulation resistane testing please help in the Periodic Inspection Reporting & Certification 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