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On Site with Matt Connecting up a new Cooker and Testing the Circuits Earth Fault Loop Impedance Zs



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so last night I got called out to a

customer's house to disconnect a cooker

because they're having a new cooker

delivered today and they need gold on

disconnected and taken away and so I'm

back here this evening to connecting the

new cooker a couple of things happened

yesterday so I thought I would perhaps

to a video on me connecting up the new

cooker circuit I thought it'd be

interesting to a couple of things that I

found which are very it must be very

common when we replace or when we when

people come across connecting up cooker

circuits so a couple of things that I

happen to me it must happen to other

people so I thought our video this one

the old cook has been taken away and and

the cooker is just our camera at the

moment and so one of the things I wanted

to to show you on the video when I

disconnected the old cooker was the fact

that it was wired up in the older red

and black 2.5 million CPC as you can see

the CPC isn't even there it's actually

broken off inside because it burns out

completely burns out and as you can see

there the line conductor is also

completely melted the cooker still work

though but when I actually disconnected

it the neutral was okay but this line

conductor was really loose in the

terminals and softly that's no good but

you know they're the sort of things that

we do come across so I've got rid of the

2.5 and we're going to wire it up in six

mil it's a couple of reasons what I'm

going to do it in six mil is because the

circuit at the moment is wide open six

mil it's protected by theta amp circuit

breaker and the cooker that I'm wired up

is a eight kilowatts cooker

freestanding cooker now when you apply

diversity to that and it means that the

cooker when diversity is applied the

amount of current that's going to be

used and is about 25 26 amps the actual

customer that I work at I'm working for

she does do a lot of cooking and so the

cooker will often be used in sort 2 to 3

hobbs and both ovens because the circuit

itself is already wired up in 6 mil the

cable that goes from the back of the

help plate the cooker outlet plate to

the actual cooker should also be the

same size as the circuit cabling it's

the circuit cable which is Marcos head 6

mil so is the 6 mil and so I'm going to

now turn the camera around and we're

just going to connect up ok this 6 mil

into the back of the cooker so here we

have the back of the cooker and this is

the actual connection plate here so what

we have is the line the neutral and the

CPC and so sometimes it can be really

awkward to know which one is the line

and neutral connections because

sometimes they're not very clear but it

you may not be able to see very well on

there but you can I can't clearly see an

L there and an end there then I can see

the earth symbol here on this one on

this cooker as well we also have this

sticker just here also says the

connections there so it's got the supply

load and then it's got the terminal one

which is their line or though says live

there

turn or two is the neutral and then it's

got the earth symbol just there I'm just

gonna prepare the six mil so what I do

is just Nick around the counter for gray

protection than that kind of cool

protection and then I just run my knife

nice and gently down along the CPC I'm

just just to where as you can see

they're just where I've knit mixer there

and then I should just should just come

off same with this one

it comes off relatively nice and neatly

so now it comes to actually connecting

you it's bit of cable into the cooker

initially what I'm gonna do is just lace

on a into position and CPC I'm just

gonna move out the way for the time

being I'm just gonna concentrate on

these to the line in the neutral

sometimes it can be a bit fiddly

especially while I'm wide trying to

record it as well it's a bit tricky but

it's gonna be in a position something

like that so what I do is just cut the

cables off

okay so there we have reject the ends of

the to expose roughly about 1215 mill of

copper and I'm just going to twist those

up like so and then I'm just gonna cut

the ends off flush so they're nice and

late and say that one looks just like

that I've also noticed that I've caught

a little bit of the gray mechanical

protection it's a little bit annoying

but I'm not gonna I'm not going to

change that now into the connections and

just make sure this is the on done

really I think they already are so I'm

just gonna off them up into it just to

make sure

we have enough rocks are these can be

really offered sometimes I think that as

I count you cut a slight little bit more

off that let's see how that looks now

and we offer it up I think that looks

nice and neat there so what I'm going to

do it's just tight connections up just

so it takes hold of the cable just like

that and then we've got this bit here

and so this bit there's a little clamp

and it just clamps over into there so

let's go in there

just tighten this up and these can be

really quite awkward

and there's unlike a little ratchet on

this so as you have to keep pushing it

in

okay then so the CPC as hopefully you

can see there it just goes into there

there's not an awful lot of it's quite

often people just take it straight

across into there but I don't quite like

doing that what I would oh I'll bend it

up and then I'll bring it back and then

I'll take it in something like that

something like that

so what I can do I can just cut that

about there let's try again and

obviously we need to remember the

correct sleeving on so I'll opt for

something else leaving

sometime today swell coming up it's

really quiet so that one should nice and

neatly into there and then hopefully

that's relatively nice and neat

certainly need to them what it was and

then we can just tighten up these

connections here

okay so I think that there looks okay so

now we've I now have wired up the actual

cooker all that's left to do now is to

actually wire it up into or connected up

into their cooker plate on the wall here

and then behind me just up here is the

isolation switch for that cooker it's

mostly I've taken the front cover off

and we've exposed three terminals

as the line as the CPC or the earth

terminal and the neutral terminal on the

right hand side yesterday when we did

this we carried out the safe isolation

as many of the other videos that we've

done this time however I thought I would

do it slightly differently maybe how it

may be done on site but I just want to

do a different slightly different way

just so we can maybe get some

discussions going some thoughts and

ideas of is this a good enough way to do

the safe isolation or not so is the

double pole switch no normally turn our

safe isolation we would isolate the

circuit in this case I haven't isolated

the circuit all I'm relying on is the

actual double pole switch because it is

double pole so that means it will switch

both the line in the neutral off so all

what I'm going to do is actually rely on

this switch now I know that this is how

it is often done okay and I just want to

see what people's thoughts are whether

or not it's safe or or not so first I'm

going to do is just confirm polarity

okay so the circuit breaker is turned on

that switch is turned on so those

terminals there are live okay

so to confirm privacy so first we're

just going to go on to the neutral

conductor then we're going on to their

my conductor and as you can see they've

got 240 volts I'm then going to go onto

the earth terminal and then the neutral

terminal a zero volts and then I'm gonna

go back between the neutral and I'm

gonna go between the earth and the line

terminal

okay that's 240 on dolls so that parity

is confirmed

not only is priority confirmed it's also

confirming that these these voltage

indicators are working so now I'm going

to turn this off simply by operating

that switch so then I can carry out to

see if these terminals have actually

turned off or if not if they're still

live so again we'll just go on to the

neutral terminal first going to the line

there's nothing there we'll go between

the neutral and the the earth and the

neutral again there's nothing there and

then last we'll go between the aligned

as you can see there's nothing there and

then I've confirmed that this is now

dead now obviously when we came out safe

isolation there is one more test to do

and that is also to confirm these I

can't say known source again we have a

proven unit so now we have the meter

wire up the six mil

into this strip so we'll just strip it's

under six mil so this time we don't need

strip back as much so I'm just gonna

Nick the sides I'm gonna just run down

the CTC to the neck but while I'm making

sure is

I've got sufficient amount of cable so

this so the curtain can be pulled

completely out and can potentially be

worked on without having to disconnect

it straight away so again I'm just going

to pour the CPC up away because I don't

want to do anything above that just yet

so what I'm trying to do here is just a

for both the line in the neutral and

just roughly position it into a position

that I'm happy with something like that

and also the CPC will go to there as

well and then you'll cut it pops me

right up there and then we'll double

back this once I come to there so

something looking like this yeah

just on those up

and I put this clamp back on

not to these too tight because it'll

quite easily snap this clump if I'm not

careful and so I think that looks okay

now you can see there's a way you can

see where I've double back the CPC but

it does go in there quite sufficiently I

should be okay

that's just time its terminals up nice

and tight

okay that's quite nice just double-check

them okay

off the ice okay now so now I'm gonna

turn it on I'm going to put back the

cover plate

so we have that was the double pole

isolator we have here again the back of

the cooker what's what we're gonna do

now is I've actually already tested the

circuit I've tested the circuit of the

continuity the CPC to make sure that it

is continuous all the way through to the

circuit and I've done the insulation

resistance test for so done there's also

an RCD protecting these circuits so

again I've done the RCD testing that was

relevant one test I haven't done is a

live thought Luke impedance test

otherwise known as the Zed s test so I

think what we're going to do I can um

it's working like it does mean working

live but I'm going to carry out that

test now and so I'm just going to turn

the circuit on and the test

automatically tests it detects 240 volts

takes approximately five to ten seconds

ARCA said if we'd use the to lead high

test that would probably knock the

circuit out the test automatically

carries out it detects the voltage and

automatically carries out the test I

said previously five to ten seconds and

some a very low current to not trip the

RCD and that has given me a reading of

point

6 6 ohms the circuit breaker protects

this circuit is a 32 amp breaker and so

we are below the maximum zs value it

needs to be below 1.1 ohms which is the

maximum zs for the for a 30 amp circuit

breaker that's nice

below that the 80% value of the on

sarcoid value therefore if there is a

problem this circuit sure to the circuit

breaker should disconnect in time so

what I'm also gonna do is do the same

test but now I'm gonna actually just

clip on to the metalwork of the cooker

so I've put my crocodile clip onto

the actual metalwork of the cooker and

then I'll just do the test again in the

line and neutral just to confirm but

that is also ok I'm also carried out an

RCD test

I've also carried out the dead testing

as well the continuity of the CPC's and

insulation resistance of the circuit

also carried out the bonding ok to make

sure that the bonding goes to both the

gas and the water is also sufficient

which it is to another video I think of

how I would possibly do a minor work

certificate for this job I know there's

people out there saying they wouldn't

bother doing a minor work certificate

for a job like this but it doesn't hurt

doing one and so I think we'll do that

but we'll do it for another video so a

cooker is now installed it needs to be

run out for about an hour or so as per

the manufacturer's instructions

obviously the packaging and the contents

need to be removed and we'll make sure

that it all works like I've said

I took the cooker out yesterday and

found that there was various problems

and so today all I've done is I've

replaced the two and a half mill cable

with a six mill cable because the old

one had burrs out anyway they just

wasn't good enough I've carried out the

safe isolation using the double pulse

which only not the normal safe isolation

method that we would probably adopt but

again I haven't moved from this location

and so there's been no there's been no

risk shall we say on me having to walk

away and leave it in a dangerous

position and so now we have a cooker

it's been tested the various tests have

been carried out such as the luke

impedance here thought load impedance

all those NS tests are that's the most

important test the RCD test and the

dentist has also been carried out along

with the along with the bonding of the

gas and water extraneous some conductive

parts all that's left to do now is to

tidy up and then I'll fill out a

certificate a minor works if occur and I

think it will be the first 18th edition

certificate I filled out now that the

18th edition is live

you