PAT Testing

[paul161]

I think the Electrician i am training with is being a bit funny. I was asked to Pat test a computer room. All the computers was plugged into four way extension leads So what i did was unplug the 4 way extension lead from the wall socket and plug it into the PAT Tester and test it altogether so i was testing the computers in pairs and the extension lead all at once . l was told this was wrong and had to test all the items separate, I asked why and he could not give me a reason. I did visually inspect the items separately. I ended up having to break it all down leads monitors and CPU and extension leads
What was wrong with the way i was testing?

 

[DurhamSparky]

Very Bad Practice....!!!!

how did you check earth continuity on both PC machines when you ran the test once..?? or did you run it a few..???

 

[paul161]

I ran the test twice on earth continuity.

 

[DurhamSparky]

still bad practice...!! reason saying that is what if the EXTN had a fault and then you back to square one messing about doing individually any way!!

 

[swiftpat]

On IT Equipment you need to test PC leads separately?

Most IT equipment now comes with detachable IEC leads or kettle leads as they are commonly called. There has been some debate if these should be tested as separate items. The latest edition of the Code of Practice for In-service Inspection and Testing of Electrical Equipment looks to clear the debate up.

According to the code of practice An appliance with a detachable power supply flex (appliance-coupler) should be tested with the code set plugged into the appliance. The cord set should be labeled and then tested separately from the appliance as follows:

A 3-core set should be tested as a Class I appliance

A 2-core set should be tested as a Class II appliance

The following inspections and tests should be made:

Visual inspection

Class I earth continuity, polarity and insulation checks

Class II polarity and insulation checks

The reason that the cord set is inspected and tested separately from the appliance is that the cord set could be used during the course of the next period to supply a different appliance. For example, if the cord set was 2-core and , during the year, was inadvertently used to supply a Class I appliance, the appliance would be unearthed and present a risk of electric shock.

Furthermore you are unable to carry out a polarity check is the leads is only tested when plugged into the appliance

By Swift PAT Swift PAT - Electrical Appliance Testing Hull, PAT Testing Hull, Portable Appliance Testing Hull, Emergency Light Testing Hull, Electrical Appliance Testing Hull Swift PAT, Hull, PAT testing, Emergency light testing. P.A.T testing, portable appliance

 

[Michelle2909]

The reason for disconnecting all ancilary equipment and testing individualy is to remove the possibility of multiple earths as some of the common ancilary equipment between the computers can have functional earths for screening purposes.
The reason leads are tested seperatly has already been mentioned, just Two notes:- polarity check on figour of eight leads is irrelavent as they can be pluged in either way around.
No 2 core lead set should be capable of pluginging into a class 1 appliance, all 3 pin plugs and socket lead sets should be 3 core otherwise a fail.

 

[grantr37]

printers and scanners commonly have a functional earth(earth used) to screen interference(electrical noise) as mentioned, and when still connected to a USB port/Network port (connection point on computer) can cause funny results, and also if testing a large format printer or combination printer/scanner/fax can cause damage if you do a 25A earth bonding test on the computers metal case....as they have a small (removable and changeable-screwed into the side of the printer in a slot) network card to connect to the office network so that all computers can share/use the printer and scanner.....the earth bonding test can damage that network card if you leave the network lead connected and dont take it out of the side of the printer before testing the computer......cards can cost around £100 to replace...