Periodic inspection report help needed

[dandawson1983]

Hi I have recently come across a property with questions I need an answer for and I hope the more experienced sparks can help. The property has an old consumer unit with no rcd protection and 3036 fuses. The boiler is wired in 2.5 t and e on a 5 amp breaker! The downstairs lighting is run in metal conduit in singles with no backboxes to light switches and twin cable to light fittings with no earth. The upstairs lights have an earth at each light but a constant low voltage of around 50-70 volts is present with lights on or off. Could this be to do with induced current or a borrowed neutral? Also no cooker circuit present however kitchen is on own ring and cooker plugged into socket ( also no cooker switch present because of this). If anyone could help out with any of this and any codes for the above I would be extremely grateul. Also if no earth present on downstairs lights I assume I can't do test readings for the periodic on that circuit!

 

[Dunc]

Boiler on a 5A breaker is no problem on the assumption that there is a FCU with a 3A fuse in it for the boiler controls. Wooden back boxes would get a code 2 IMO. On the upstairs lighting, what are you measuring between to get the 50-70V? Regarding testing the downstairs lights the only test you can do is a IR between L and N and comment on the lack of CPC giving it a code 4 so long as no Class 1 fittings are present. Finally, what is the rating of the cooker?

 

[mattmoo1974]

If you google the no earth on lighting mate theres a guide from C@G i think about what to do, I had/have it as PDF if i find it i ll send it on to you.

 

[dandawson1983]

measured between live and earth and live and neutral on voltage setting as tried to do my zs on each light and it will not register because of the low voltage. also light fittings are ancient so assuming they will be class 1.

 

[roukel01]

Sounds like a nice rewire to me!

 

[dandawson1983]

by the way supply is tns

 

[dandawson1983]

what do u mean by vehicles?!

 

[mkoffulham]

Hi when doing a pir i found on zs test that sockets were 1.2 ohms is this ok cos max zs in bs7671 32amp breaker is 1.44ohms why do you have to mulitply by 0.8?? to get 1.15ohm cheers

 

[telectrix]

you multiply by 0.8 to allow for increase in resistance with temperature rise. so your reading is borderline. probably either a spur off the ring or poor connections.

 

[pushrod]

Hi when doing a pir i found on zs test that sockets were 1.2 ohms is this ok cos max zs in bs7671 32amp breaker is 1.44ohms why do you have to mulitply by 0.8?? to get 1.15ohm cheers

If the circuit is protected by a 30mA rcd then it is fine as you can take 1667Ω as your max. If not then it is probs a case of finding poor connection, although upgrading main earth and or tails (if appropriate) could also be just enough to improve your 1.2Ω reading.

 

[mkoffulham]

i also dont know much on the voltage drop side of thing how do i work it out ??
also when measuring the pscc what sort of reading should you get and what if ze is too high??
do you have to install an isolator on cable if main head is more than 3meters away from meter??

 

[pushrod]

was my last answer useful, ie worthy of thanks?

 

[malcolmsanford]

Hi when doing a pir( I assume that your a competant person then or even an electrician) i found on zs test that sockets were 1.2 ohms is this ok cos max zs in bs7671 32amp breaker is 1.44ohms why do you have to mulitply by 0.8??(you don't know this and your doing a PIR) to get 1.15ohm cheers

i also dont know much on the voltage drop side of thing how do i work it out ??( is this a general question as VD is something you would do at the design stage, or if there was a problem with an appliances)
also when measuring the pscc what sort of reading should you get and what if ze is too high??(why would the Ze be high, what would you expect the Ze to be)
do you have to install an isolator on cable if main head is more than 3meters away from meter??(normally yes)[/QUOTE]

Can I ask do you feel competant enough to do PIR work after what really are basic questions.

 

[nickblake]

was my last answer useful, ie worthy of thanks?

i thought it was a great answer so ill thank you

 

[mkoffulham]

i also dont know much on the voltage drop side of thing how do i work it out ??( is this a general question as VD is something you would do at the design stage, or if there was a problem with an appliances)
also when measuring the pscc what sort of reading should you get and what if ze is too high??(why would the Ze be high, what would you expect the Ze to be)
do you have to install an isolator on cable if main head is more than 3meters away from meter??(normally yes)[/QUOTE]

Can I ask do you feel competant enough to do PIR work after what really are basic questions.

HI i am an electrician but have not done my 2391 yet. i have been collage but they dont teach you much just to pass the exam i am trying a pir at home to get use to it and i thought i would ask some questions that iv had diffrent asnwers for.
is this a crime??
alot of people just write down results and dont now why that are what they are!! not everyone has the experience like others that why it is useful on here. we dont need sarcastic comments just trying to lean!!

 

[mattmoo1974]

Ze is external ie what teh DNO gives you, So it shouldnt be high TNCS 0.35 and so on.
I think you mean if your Zs is high, Then you look at the tabluated value for the MCB and may have to put in a smaller 1 or larger cble to bring your Zs value down.
Oh and MK i total agree with you on the college front. Testing sadly is over looked i feel, Needs to be one to one not a huge group exercise
Hope this helps mate. Oh buy yourself a GN3 but these are changing soon so either get 1 now or wait.
Think this book will explain a few things your asking here.

 

[malcolmsanford]

I think if you had posted your reply that you have, to my post first, then help would have been a lot more forth coming.

It sounded from your OP that you were carrying out a PIR as a job. I just thought it was prudent that someone pointed out that if it were a job, then the basic questions you are asking, belies the fact that you are not competant enough to be carrying out PIR's safely and/or interpret the results you get to give a formative assement on the installations condition.

I do now appreciate that your doing you own home, and that you are in the process of learning. I'm sorry if you felt my post was sarcastic, and if you had led with I'm doing a PIR on my home to learn ....................then as I mentioned I would have been more helpful.

There are quite a few people in our industry that are not as ethical as you, and decide to learn at the expense of the public, which IMO is selling our industry short as it tars everyone with that same brush of being incompetant. As like me the forum will know that your learning and I'm sure will be of a great help to you.

 

[mkoffulham]

ok so when doin a pir what would you code if service head was 10meters away from meter or meter was 10m away from fuse board and had no isolator to protect cable??

 

[mkoffulham]

also in commercial if the shop had no emergency lights or fire alarm systems what would you code that? do you have to code?

 

[nickblake]

First question is a code 4 2nd question there would be no code as its not a requirement in the regulations to install fire and emergency lighting in commercial premisis ,that would be down to the council and fire service , how ever under building regulations in domestic premisis it is that is for new builds , but if i was doing the PIR i would reccomend the installation of smoke detectors etc