Discuss Testing for electrical separation 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

Pretty Mouth

-
Esteemed
Arms
Reaction score
2,812
Hi all.

I'm a member of a FB group for people trained through a particular training provider. Recently someone posted a query for testing for electrical separation for shaver sockets, and my ex trainer responded with the following method (cut n paste verbatim):

you need to confirm separation of the transformer in the unit itself, and then segregation of the circuit supporting the shaver from the rest of the circuits of the install. to test the shaver unit before install on the bench, lift off the cover from the terminals( this will be slightly different for each manufacturer) and link line to neutral on the low voltage side with a small cable link. then using the insulation resistance setting on 500v test for 60 seconds from primary side to secondary( brown probe on primary and green probe on secondary) . to test the segregation take the L,N and CPC of the circuit out of the board and clip them together with jumper leads, crocodile clip the brown probe on at 500v to the jumper leads and with green probe test to the other circuit terminals at the breaker, earth bar and neutral bar, the result should be an open circuit reading above 1Mohm to pass.

My problem with the above in bold, is that any parallel paths (eg sup bonding, circuits sharing the same metallic enclosure etc) between the CPC of the circuit being tested for segregation, and the earth bar will give low IR/continuity. Perfectly healthy and normal, but a fail according to the above method.

I am now locked in an argument with my ex trainer. I've tried explaining every way I can, including diagrams, to show how it doesn't work, but he is insistent that it does, so insistent that I'm starting to wonder if there's something I'm missing. I would appreciate it if the good members of the forum would put me straight on this.
 
Shaver sockets provide electrical separation.I don't understand the segregation part, what is being tested for segregation.
I'm not entirely sure myself. The bench test has to be to ensure separation between the electrically separated live conductors and the terminals connecting the unit to the main installation. That bit I get, and is where the testing would end for me.

A segregation test as I know it is to check that the live conductors of a circuit are not connected to those of any other circuit. Why this is deemed necessary when checking a shaver socket I cannot work out. Unless it's sharing a backbox with accessories from another circuit (highly unlikely) I can't see how there could possibly be any connection between the electrically separated part of the shaver socket and other circuits.

In any case the test as described simply doesn't work
 
There is no need for any additional electrical seperation of the supply circuit which feeds an isolating transformer used to provide a seperated supply.

There is also normally no need to test the seperation provided by a small self contained unit such as a shaver socket, it is manufactured and type tested to the appropriate British standard.
 
Was this just a college bench test to demonstrate the test for separation or are they suggesting you do this with any shaver socket you install. As above these things are type tested by the manufacturer to ensure they are compliant.
 
Westward, Davesparks, thank you both for your replies. What you have both said makes perfect sense.

IIRC we were taught to carry out the bench test on all shaver sockets to be installed. To be honest, I tried to do it once in real life and gave up as there was no access to the electrically separated conductors for the shaver socket I was fitting.
I don't remember being taught anything about testing the circuit feeding the shaver point for segregation, but possible I could have forgotten it. The only place I have ever heard of testing shaver sockets in this way is at the training provider, I have never read about or seen this test in books, guidance notes, youtube etc.

The argument is ongoing. I'm not sure if there's some pride thing going on and he's just arguing to be seen to be correct or what. I'll cut and paste it here so you can see what I'm up against.
[automerge]1576694477[/automerge]
Ok, maybe I won't cut n paste it, unless you guys want a major essay to read?
 
Last edited:
sometimes it is best to nod the head and let it lie,

then you can go about your business whilst casually ignoring a piece of bad advice.

I am with the rest of the guys, if its approved and tested for a particular task, it is not the installers job to try and replicate the tests they should have done before it left the factory.

do we test circuit breakers at 1.5 rated capacity and time how long it takes to trip?
just incase a 32A has slipped into the print line for the 16A ones?
 
sometimes it is best to nod the head and let it lie,

then you can go about your business whilst casually ignoring a piece of bad advice.

I am with the rest of the guys, if its approved and tested for a particular task, it is not the installers job to try and replicate the tests they should have done before it left the factory.

do we test circuit breakers at 1.5 rated capacity and time how long it takes to trip?
just incase a 32A has slipped into the print line for the 16A ones?
You are of course completely correct. The problem is I'm not very good at letting things lie, particularly when those in positions of authority/superiority are clearly wrong yet arguing to the ends of the earth that they are correct. I'm quite argumentative when I believe I'm right
 
A wise man only fights the battles that he knows he can win.

it is possible to win a battle but loose the war, look at it in the longer term.

I have known a few people who were technically great sparks or engineers but they struggled to climb the ladder because of there people skills.

YOU and only You can decide what the best way forward with this one is, but think before you act.

p.s. i know that you girls also do this electric stuff and i wasn't trying to exclude you.
so it is possibly better to say,
A wise person only fights the battles that they know they can win.
 
p.s. i know that you girls also do this electric stuff and i wasn't trying to exclude you.
so it is possibly better to say,
A wise person only fights the battles that they know they can win.

You can dispense with the politically correct garbage as far as I'm concerned.

I have no problem with words like Chairman, Fireman, Milkman... if sh1te like that is the only thing someone has to worry about then they need to get a life.
 
I suspect that the trainer is getting confused with what is needed when the isolating transformer is somewhere other than the point of use, with its secondary circuit being carried through installation cables. In that case, it is necessary to test for electrical separation between those cables belonging to the separated circuit and the rest of the installation, after disconnection of any earth fault monitoring equipment.
 
I personally think the trainer is demonstrating the testing of electrical separation but has gone totally off piste where he talks of segregation of the supporting primary circuit.
 
I suspect that the trainer is getting confused with what is needed when the isolating transformer is somewhere other than the point of use, with its secondary circuit being carried through installation cables. In that case, it is necessary to test for electrical separation between those cables belonging to the separated circuit and the rest of the installation, after disconnection of any earth fault monitoring equipment.

I think this is probably what's happened. Here are a few of the points he has made:

this test is to prove that the circuit with electrical separation is fully segregated from the others so there can be no fault cross paths

we teach this and demonstrate it on every inspection and testing course, it is to show that the conductors of the circuit supporting the shaver unit are not interconnected to another circuit to meet Part 6 of BS 7671.

So that you prove it is a complete separate circuit with no interlinks as per section 413 of BS7671, and the only way to do this is to test as described.

I honestly don't think the guy has a clue, but there's 3 trainers at the centre, all working together. You'd have thought 1 of them would have sussed it out wouldn't you? But as he said, taught on every course, so he's not going to back down when semi-publicly challenged by some domestic cabbage such as myself, even if he did see my point.

I do wonder sometimes how people get where they are in life.
 

Reply to Testing for electrical separation 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