New Build Housing Project

[trev]

New build housing project in the middle of a very hot summer (anyone remember both those things?) so everything is bone dry. One of your colleagues did the first and second fix so you have the job of testing IR is down just under 2 meg.
Discuss.

 

[Paul.M]

I'm guessing this is a global IR Trev?

 

[trev]

Oops well spotted mate. The IR on the lighting circuit is down to just under 2 meg. Sorry guys.

 

[Baker1988]

im honestly not sure about this one if its newly rewired why would it have only 2 meg, the only thing i could think is that they have cut abit of the isulation from pulling the cable in probily caught it on some thing, i would start by doing global ir then switching 1 circuit at a time off till i find the circuit that is the problem say its the sockets then i would guess about half way on the circuit undo the socket and disconnect both legs and do a ir on each leg that would tell me which side of the leg the fault is on then work my way back doing the same till i find between which socket it is and replace that bit of cable but as i say im not sure so a guess but isnt 2 meg ok according to regs any thing over 1 megohm is ok but any thing under 2 megohms should be investigated so in all fairness 2 meg is ok

 

[High Tower]

Ok forget the base value of 1Mohm we know this just scrapes it, problem is its a brand new install and should be >500

 

[Baker1988]

Ok forget the base value of 1Mohm we know this just scrapes it, problem is its a brand new install and should be >500

yeah it should be off the scale for ir that is what you would expect but as i said i dont know why this should happen except they have sliced the insulation while pulling in the cable

 

[Floody]

Ill go with what we already know to start.

its a hot summer, possible heat damage to insulation?

 

[Baker1988]

Ill to go what we already know to start.

its a hot summer, possible heat damage to insulation?

thats a good point i totally forgot about where it said hot summer it probily has melted a bit

 

[Floody]

The insulation must be able to withstand some heat as current flows through it. But on a boiling day in the back of a van where cable is left, it can become like an oven in there.

your collegue has done first and second fix, so you have no idea what the state of the cable was going in.

 

[Paul.M]

Ok forget the base value of 1Mohm we know this just scrapes it, problem is its a brand new install and should be >500

HT I dont understand your figure of >500 M Ohms for a new install. Rather I've forgotten something or I dont know something???


Ha, I now understand what you are saying HT. Yes it should be BUT that will never be in a C&G exam question.


Ok lads, 2 points on IR testing.

1. A global test on a new or existing installation should be higher than 2 M Ohms, lss than that requires further investigation.

2. An individual circuit IR test should be greater than 1 M Ohm.

But saying the above, if I got anywhere near these levels on a new install I would be testing everything that my work mate has installed to find out why. It should be over 500 M Ohms with new cable etc. Scratchy head time for the I&T lol.

 

[Baker1988]

The insulation must be able to withstand some heat as current flows through it. But on a boiling day in the back of a van where cable is left, it can become like an oven in there.

your collegue has done first and second fix, so you have no idea what the state of the cable was going in.

well normal thermoplastic cable (pvc) has a operating temperature of 70 degree c so it can withstand that before it starts melting and there is also thermo setting cable which can withstand 90 degrees c

 

[Paul.M]

Post #3, concentrate on the lighting circuit lads

 

[Baker1988]

the only other thing i could think of is that there is either a light bulb still in one of pendents or that there is a small neon light somewhere like on a fuse spur or something that would drop the ir by a lot so disconnect the bulbs and change the fuse spurs with neons and connect then with a chock block or something

 

[Paul.M]

the only other thing i could think of is that there is either a light bulb still in one of pendents or that there is a small neon light somewhere like on a fuse spur or something that would drop the ir by a lot so disconnect the bulbs and change the fuse spurs with neons and connect then with a chock block or something

I like your answer and the way your thinking but when would we put a neon fsu from a lighting circuit? Yes that is possible but I really like the idea of light bulbs/lamps

 

[Baker1988]

I like your answer and the way your thinking but when would we put a neon fsu from a lighting circuit? Yes that is possible but I really like the idea of light bulbs/lamps

true there wouldnt be any need to really as its only 6amp mcb and you wouldnt be down grading the cable size so no real reason too, there could be a celing fan/light

edit:
there could be an emergency light on the circuit they have a neon light and a battery pack

 

[trev]

Having been absent from the thread for a wee while I'm giving the point to Baker for post 4. It was a case of the plasterer striking yet again. A loop had been left in a cable and the insulation had a tiny little nick in it having been pressed hard against a joist by the idiot boarder.

I'll pay a bit more attention next time but I have to admit, I like putting the easy ones up as they're easy to overthink.

 

[Baker1988]

Having been absent from the thread for a wee while I'm giving the point to Baker for post 4. It was a case of the plasterer striking yet again. A loop had been left in a cable and the insulation had a tiny little nick in it having been pressed hard against a joist by the idiot boarder.

I'll pay a bit more attention next time but I have to admit, I like putting the easy ones up as they're easy to overthink.

YEAH i win haha i love these posts

 

[Baker1988]

think i may put my profile address on my cv it may help me get a electrical job if they come on this forum and see my profile

 

[Paul.M]

Hoy Trev, you said nothing about plasterers. You said it was "dry" so therefore I put aside the muck spreaders mishaps of putting their cr4p onto our cables. Mind you, I should have asked lol.


Last year on a hotel rewire the plasterer turned on the mcb so he could have the lights on. Whoops he touched the perm live to a switch and got a shock and tried to blame me pmsl. (it was my faut, I did'nt lock it off lol). Thats what you get when you touch something you know nothing about and get a belt. He was'nt happy with me but he soon calmed down once I raised my level of voice to his, fooking rounded door handle. We became good mates after that but he still blames me :rofl:

 

[Paul.M]

think i may put my profile address on my cv it may help me get a electrical job if they come on this forum and see my profile

Just be careful of doing that mate, it back fired on me 2 years ago when an employer (sub contracted to him and he wanted to pay me less than what was agreed) wanted to have a go at me. Tried to make me look like a fool but all the members stuck up for me and he fooked off quick. Besides I told him that I would inform the forum of his "professional conduct within his working practice's" and then inform his scheme MD (I have his scheme membership company director phone number in my phone lol, nice guy, I get on with him).

Do what you think is best for you but just be careful mate. It takes 1000 posts to become respected within our community and only 1 post from a kn0b head to take it all away. What you say on here stays for the history of time. Your unborn children and childerns children will be able to see what you have posted up in decades to come, just be aware of that.

 

[Baker1988]

Just be careful of doing that mate, it back fired on me 2 years ago when an employer (sub contracted to him and he wanted to pay me less than what was agreed) wanted to have a go at me. Tried to make me look like a fool but all the members stuck up for me and he fooked off quick. Besides I told him that I would inform the forum of his "professional conduct within his working practice's" and then inform his scheme MD (I have his scheme membership company director phone number in my phone lol, nice guy, I get on with him).

Do what you think is best for you but just be careful mate. It takes 1000 posts to become respected within our community and only 1 post from a kn0b head to take it all away. What you say on here stays for the history of time. Your unborn children and childerns children will be able to see what you have posted up in decades to come, just be aware of that.

yeah thats a good point actually, dont think i will do it now i dont want that to happen

 

[High Tower]

Well done yet again lads, dont forget the goal isnt to have you guys answering every situation correctly, the goal is to get you guys thinking and figuring things out, so far you are doing brilliantly.

No employer will ever judge you on the posts that you make on a forum somewhere, you chance to shine above other applicants is your ability to reason a problem and think latterally, this you are both doing well!!

 

[High Tower]

Also........... further to this thread, i will give you 3 IR readings found on a lighting circuit, can you interpet them and give the most like causes???

A, 0.00 Mohm

B, 0.02Mohm

C, 1.85 Mohm

 

[Paul.M]

No employer will ever judge you on the posts that you make on a forum somewhere, you chance to shine above other applicants is your ability to reason a problem and think latterally, this you are both doing well!!

In this section we are all protected by a very strict admittance rule, so no worries in here.

In my situation I subbied for a small firm and I told him that I was on here. After a large house rewire that he tried to over charge the customer by a couple of grand he tried to attack me via this forum to reduce the amount of money he needed to pay me. He made me look like a fool by the words he wrote but it did'nt work. I did not rise to his condescending remarks and I just phoned him to have it out with him. 2 months later he paid up and we sat down over a few beers and sorted things out. I was very p1ssed off with what he said on this forum and he is aware of my retaliation if he tries to do it again. (most of it was made up to show me up btw).

This is one of my many experiences of forums V's real life. Only had one other bad experience but the other dozen are/still are brillient. I've made some great real life friends from this forum and made about £2k from diy posters (doing a job tomorrow infact) and another couple of grand from working for/with other sparks on here so its not all bad. Just be careful.

 

[High Tower]

Mate i think any of us that know you appreciate your honesty and integrity

 

[Paul.M]

Mate i think any of us that know you appreciate your honesty and integrity

Thank you HT, very kind of you.


"It takes time, effort and hard work to build a good reputation, but it only takes one mistake and a man with a sledgehammer to take it all away and knock you down to your foundations."

Paul Maddinson of Leeds said that years ago and I still stand by my words to this day.