Pat test failed,What mega reading do i need

Re: Pat test failed,What mega reading do i need

a class 1 static appliance(heavier than 18kg)is normally tested at 1Meg. if its reading less than that then you can sometimes bring the reading back up by running it for a while,(admittedly moreso on cookers/ovens) then retest.
however to confuse matters further our tutor on city and guilds course said that you can pass a static appliance at 0.3meg if it has a heater in it.

Re: Pat test failed,What mega reading do i need

Just pulled the “Code of Practice for In-Service Inspection and Testing of Electrical Equipment – 3rd edition” off the shelf to check what it says and help to clear up any confusion.
In 15.5 “The Insulation Resistance Test” it gives a table (15.2)which says:-
“Class 1 heating and cooking equipment with a rating equal to or greater than 3KW = 0.3Mohm”
“All other Class 1 equipment = 1.0Mohm”
“Class 2 equipment = 2.0Mohm”

In note 1 it states “Certain heating and cooking appliances may be unable to meet the insulation resistance requirements, such as where metal sheathed mineral-insulated heating elements are used. It may be necessary in some cases to switch on the appliance for a period of time to drive off absorbed moisture before commencing testing. Additionally the touch current measurement of section 15.6 may be carried out.”

And finally just to clarify where 0.5Mohm may have come from we go back up the page and find this paragraph “The applied test voltage should be approximately 500VDC. The test instrument should be capable of maintaining this test voltage with a load resistance of 0.5Mohm”

Re: Pat test failed,What mega reading do i need

Procedure & guide Pat Testing

Classes Of Appliances

Class 1 Earthed Appliances = No symbol
Class 2 Double Insulated = ➡ ( http://www.google.co.uk/imgres?imgurl=h … m=1&itbs=1 )

Visual Inspections

1 Check For Signs Of Cracks,damage or Heating
2 Ensure plug Pins are Insulated
3 check Plug is Correctly Terminated
4 Check connections are tight
5 Ensure correct fuse size And that fuse carries Asta symbol :arrow:( http://www.google.co.uk/imgres?imgurl=h … m=1&itbs=1 )
6Check cable Anchorage is secure

Fuse Sizes

1 . IT Equipment = 3 Or 5 Amp
2 . Motor Powered equipment = 10 Amp
3 . Heating equipment = 13 Amp

CABLES

1 No connector Blocks or Joins
2 No Lumps hard or soft Spots
3 No damage to insulation or cuts to cable

Appliances

1 No Missing Screws; or cracks or damage to Appliance casing
2 no signs of Overheating
3 On/off switch Operates correctly
4 No excessive contamination to the casing

Extension leads
Extension Leads Must be Fitted with A Minimum Of 1.25mm cable and Fitted with an earth cable.

If Any of The 1st Procedure Above Have Failed There Is No need To carry on With The Other Tests Either put A Failed Sticker On IT Or Record the Information In A Log Or Carry Out A Safe Repair.

Electrical Tests required

1 Earth bond Test
2 insulation Test
3 Polarity Test
4 IEC cables To be LABELLED and Tested SEPARATELY

EARTH BOND TESTS

ONLY APPLICABLE FOR CLASS 1 APPLIANCES AND 3 CORE LEADS
ATTACH EARTH BOND CLIP TO APPLIANCE CHASSIS

MAXIMUM READING
0.1 Ohms+CABLE RESISTANCE (REFER To Cable resistance Table)
Earth Bond test Currents

IT = Equipment = 100 0r 200 MA
OR
ALL Other Class 1 appliances
Up to 1.5Times The rating of The Fuse or A maximum Of 25 Amps.

[b] Cable Resistance

Cable csa(mm)………….. ohms Per Metre

0.5mm =====================0.390 0hms
0.75mm=====================0.0260 Ohms
1.0mm======================0.0195 Ohms
1.25mm=====================0.0156 Ohms
1.5mm======================0.0133 Ohms
2.5mm======================0.008 Ohms
4mm========================0.005 Ohms
Examples
A 15m extension cable reel with A cable size of 1.5mm would have an earth bond pass mark of 0.1995 Ohms =( 1.5m x 0.0133 Ohms )

an appliance fitted with a 7meter 1mm cable would have an earth bond pass mark of = 0.2365 Ohms = (0.1+(7m x0.0195 Ohms

Insulation and Leakage Tests
The Insulation And leakage test below are Applicable to all types Of appliances.

if appliance is IT/ The electronic Insulation Test can be Substituted for the leakage test.

When testing Class 2 appliances ensure earth Bond Clip Is In contact with the appliance.

Ensure appliance switches are in the on position where possible.

Insulation Test

Minimum Allowable Insulation Test

Class 1 Heating Appliances = 3kw = 0.3 M Ohms

Other class 1 Appliances = 1 M Ohms

Other Class 2 Appliances = 2 M Ohms

Leakage Tests WARNING POWER ON TEST ENSURE THAT THE APPLIANCE IS IN A SAFE STATE

MAXIMUM LEAKAGE VALUES

Portable or hand held Class1======= 0.3m Ohms

class 1 heating appliances========= 0.75mA or 0.75mA Per KW.max 5mA.

Other Class 1 appliances ================== 3.5mA

Class 2======================================0.25mA

I would Advise Anyone with Limited Knowledge Reading This Thread To go and do a course.
There May be 1 at your local Tech College twice a year That Could Cost you Around £500.00 or there Are Some Courses Which You May have To Travel And They Are Usually Expensive Plus You will Need Board And Loge For About Theree Days

Or Do one Online With no Pressure ➡ http://www.google.co.uk/url?sa=t&source … GnNuTtJSIg

Happy and safe Testing garn… 🙂

Re: Pat test failed,What mega reading do i need

Iv had some training with PAT TESTING few years back now, can someone clear up that when checking for insulation 1 clip on earth and 1 clip on LIVE and NEUTRAL, am i correct in assuming SOME timers wont switch in the heater and motor until the machine is in use? thus giving an inaccurate reading?

i always run with RCD during test incase old style fuse box in property?

simonb

Re: Pat test failed,What mega reading do i need

eastlmark wrote:good info there but, is a washing machine, as it contains a mineral heater, classed as heating appliance?

There is no definitive answer in the book so it is one of those questions where you have to try and interpret the guide as best as you can, the way I tend to look at it is this:

If there is more than 3KW of heating elements then in theory at least I would be able to class it as a heating appliance and pass it at 0.3Mohm, however in practice I prefer to make 1Mohm my standard pass/fail mark for everything and between 1Mohm and 8Mohm my advisory limits*, I do this because we all know how jittery some control boards can get when an element gets near or below the 1Mohm mark and when combined with the cumulative effects of other appliances it can be enough to knock out some RCDs, it also isn’t that hard to reach most of the time.

*Advisory limits = a part that looks like it isn’t far from failing and may or may not last a decent time after my visit, customer given choice of having pre-emptive replacement for just the extra cost of part or face possible second call out and parts within a short space of time.