Discuss wiring in dado trunking in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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nicsin02

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hi guys quick question, got sent out to a job today to connect in sockets that are lying on the floor in dado trunking for office computers etc, the whole room is wire in a ring protected by a 32a mcb to 5 seperate 20amp double pole switches, these switches feed about 5 or 6 sockets each on a radial, the electrician in before me wired an extra 16 sockets on to one of these radials meaning the douple pole switch is feeding 22 sockets, is this ok/ they are wired in 2.5mm single cables in trunking which can take 24a according to regs, so would the 20amp double pole switch blow if the radial load exceded more than 20 amps meaning the 24a cable will be protected, just making sure thanks
 
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ab1978

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  • #2
hi
the double pole switch is rated at 20amp not fused, so would overheat not blow i'm afraid. i would consider changing the radial with 22 sockets on it. don't understand why some would wire it that way to be honest
 
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Guest123

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I'd be a lot more worried about overloading the RFC at that point as technically there are now 22 spurs!!!!!
 
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Swicade

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Surely each 20a double pole switch should be seperately fused when spurred off the ring the way it is now.......

Seems to me a totaly bad install without the extra 16 sockets....the way i read it there's a total of 42+ spurs off a ringmain? (4x 5-6 sockets + 1x22 sockets)
 

Strima

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Sounds like a right bag of spanners and a fire waiting to happen.
 
Firstly, you are only allowed as many spurs off an RFC as you have sockets on it. Secondly, if I'm reading it correctly, you have several spurs off spurs, which is totally unacceptable unless they are fed from a 13 SFCU from the RFC. This sounds like it needs redesigning asap.
Your question "
so would the 20amp double pole switch blow if the radial load exceeded more than 20 amps meaning the 24a cable will be protected, just making sure thanks" has made me very worried....
 
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Adam W

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  • #7
If you're after a quick fix you could replace the DP switches with FCUs, but ideally it wants redoing properly.
By 'properly' I mean conventionally, not trying to be 'clever'.
 
In your position I'd be thinking about the load and how it could be spread around the RFC and splitting the suite up so it could be better served by more than one circuit.
Either that or, as some of my learned friends have implied, get some fire extinguishers in there:)
 
Would it not be easier to introduce another leg to the 22 points and make it a ring on its own if the board is not too far away.
 
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nicsin02

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sounds like a pretty ****ty install, so what does the "20 amps" actually mean on a douple pole switch i would have fought it would stop the cable exceeding 20 amps of current, the sockets only have single earthing aswell!!:banghead:
 
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Guest123

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  • #12
sounds like a pretty ****ty install, so what does the "20 amps" actually mean on a douple pole switch
Thats just the maximum rating of the contacts of the switching mechanism. Anymore and they will start to overheat.
 
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nicsin02

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  • #13
Thats just the maximum rating of the contacts of the switching mechanism. Anymore and they will start to overheat.
so what would u reckon would be the easiest way to fix this i have only an hour in this office 2morrow morning only thing i can think of is replacing swiches with fused spurs any ideas
 
sounds like a pretty ****ty install, so what does the "20 amps" actually mean on a douple pole switch i would have fought it would stop the cable exceeding 20 amps of current, the sockets only have single earthing aswell!!:banghead:
Are you really working on electrical systems without knowing the difference between a switch and circuit protection? Please tell me you are just teasing. :)
 
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nicsin02

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  • #15
Are you really working on electrical systems without knowing the difference between a switch and circuit protection? Please tell me you are just teasing. :)
simple mistake:sick: just have to replace with a fused spur and hope they dont exceed their 13 amp allowance
 
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Guest123

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  • #16
so what would u reckon would be the easiest way to fix this i have only an hour in this office 2morrow morning only thing i can think of is replacing swiches with fused spurs any ideas

Tell them what they have is pants and requires quite a bit of work to be put right....more than an hours worth!!!
 
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nicsin02

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  • #17
Tell them what they have is pants and requires quite a bit of work to be put right....more than an hours worth!!!
i will put that to them 2morro but i only have an hour to make it as safe as i can and i will say to gaffer about a re-wire
 
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1shortcircuit

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  • #18
i will put that to them 2morro but i only have an hour to make it as safe
Well that's easy peasy lemon squeezy...

Enter building, inform everyone that you need to switch off offending circuits for a little while, once everything is shut down and safe to isolate, enter consumer unit, identify offending circuits, swicth off, lock off, write down bosses number, give to person in charge and inform them that you have made safe in allocated time and to rectify the situation they need to speak with your boss..... Exit with smile from ear to ear knowing that installation is all safe and prepare yourself for a really sound nights sleep. :77:

:thumbsup
 
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nicsin02

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  • #19
Well that's easy peasy lemon squeezy...

Enter building, inform everyone that you need to switch off offending circuits for a little while, once everything is shut down and safe to isolate, enter consumer unit, identify offending circuits, swicth off, lock off, write down bosses number, give to person in charge and inform them that you have made safe in allocated time and to rectify the situation they need to speak with your boss..... Exit with smile from ear to ear knowing that installation is all safe and prepare yourself for a really sound nights sleep. :77:

:thumbsup
i would get sacked for that mate, will just have to stick with 13amp spurs for now, cable wont go on fire so i WILL sleep sound, dont care if 13amps aint enough for their sockets they can deal with my boss about that, as long as it wont burn :cheesy:
 

darkwood

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What concerns me here nicsin02 is your basic lack of understanding to Reg's regarding the several areas mentioned above that you never even touched on yourself, as well as a lack of understanding of the function of a 20amp switch.

I assume its and office with computers and alot of them, so to re-enforce what farmelectrics said you have got a functional earthing system and these radials are unlikely to be set up to allow for this or the ring main in that case.
If the socket circuit isn't under the supervision of an instructed person then RCD cover will also be required and i wouldn't be wiring more than 5 or 6 computers to each circuit unless using a SI unit which allows for an increase in this no'.
Basic understanding of regulations which are clearly shown in picture form in the OSG or Reg's to the allowances for spuring of ring circuits seems to be missing from your knowledge which is of great concern.

What are your qualifications and experience as your post and replies are showing a lack of competence, you shouldn't be undertaking this work if your asking the questions you are and also having other major areas of concern been pointed out to you.

Let me make this clear Nicsin02, if you change, alter or make any addition to this circuit/s then you are responsible for its compliance and it will have to meet 17th addition once you do, the high integrity earthing and the need for it is a great concern in my mind as it is a safety issue if not done correctly.

I hope you can take this as valuable advice and not a dig in any way.
 
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1shortcircuit

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  • #21
i would get sacked for that mate, will just have to stick with 13amp spurs for now, cable wont go on fire so i WILL sleep sound, dont care if 13amps aint enough for their sockets they can deal with my boss about that, as long as it wont burn :cheesy:
How do you work that out?

You're given a ridiculous amount of time to rectify what sounds like a ballache of a job so you are making safe within the allocated time?:D I don't see the issue;)

So what have you told your boss and what has he suggested you do?

I love working for myself :devilish:
 

Marvo

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I would just make sure all cabling is protected by correctly sized MCB's or fuses. Explain to the customer the problems with the existing installation and quote accordingly for remedial work.
 
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doublecuff

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  • #23
To quote the band Orange Juice. Rip it up and start again.
 
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nicsin02

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  • #24
What concerns me here nicsin02 is your basic lack of understanding to Reg's regarding the several areas mentioned above that you never even touched on yourself, as well as a lack of understanding of the function of a 20amp switch.

I assume its and office with computers and alot of them, so to re-enforce what farmelectrics said you have got a functional earthing system and these radials are unlikely to be set up to allow for this or the ring main in that case.
If the socket circuit isn't under the supervision of an instructed person then RCD cover will also be required and i wouldn't be wiring more than 5 or 6 computers to each circuit unless using a SI unit which allows for an increase in this no'.
Basic understanding of regulations which are clearly shown in picture form in the OSG or Reg's to the allowances for spuring of ring circuits seems to be missing from your knowledge which is of great concern.

What are your qualifications and experience as your post and replies are showing a lack of competence, you shouldn't be undertaking this work if your asking the questions you are and also having other major areas of concern been pointed out to you.

Let me make this clear Nicsin02, if you change, alter or make any addition to this circuit/s then you are responsible for its compliance and it will have to meet 17th addition once you do, the high integrity earthing and the need for it is a great concern in my mind as it is a safety issue if not done correctly.

I hope you can take this as valuable advice and not a dig in any way.
listen "darkwood" i made a simple mistake with the 20a switch, it aint my job or site, i just started with the company and was told to check wot breaker worked which circuit and how many points etc.... spoke to the electrician and he told me what hes been doing, didnt think its sounded quite right hence the reason i posted it on form, i have to go out there tomorrow morning to connect 2 data points then i have to be at another job for 9am, the sockets are protected by a 32a mcb not an rcd, i know all about the earthing arrangements for a circuit for which computers are running, in this case this circuit has single earthing, so tommorow i will change the switches for spurs and let my gaffer know, it aint my job so the electrician who did it can take responibilty i will make safe as i can, and for your information kid i have 17th edition, 2391, PAT testing and my compex................. hope that doesnt sound too condesending pal.
 
" it aint my job so the electrician who did it can take responibilty"
You are going to be the last person working on this "circuit" so unfortunately it's going to be your responsibility if it goes horribly wrong
 
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Swicade

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  • #26
Fit the 2 Data points (your job)...leave the electrical socket install alone (as it's not your job)....report your concerns to your boss and let him/her deal with it.

Job done...alls good. IF you change the switches (not your job but is the right thing to do) you then take responsibilty for anything going wrong. The way OP was typed it sounded like it was your job to sort out tbh but that's obviously not the case.
 
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nicsin02

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  • #27
Fit the 2 Data points (your job)...leave the electrical socket install alone (as it's not your job)....report your concerns to your boss and let him/her deal with it.

Job done...alls good. IF you change the switches (not your job but is the right thing to do) you then take responsibilty for anything going wrong. The way OP was typed it sounded like it was your job to sort out tbh but that's obviously not the case.
correct changing the switches is the right thing to do, nothing will go wrong if protected with a 13amp fuse, still wont be rcd protected, still wont have correct earthing... but wont go on fire, it is an office that has been built for a while i think , i think my boss has priced for putting in an extra 16 sockets not knowing that the earthing arrangemnt isnt suitable so he will hace to arrange a price for rewiring an earth back to DB, our company fiited the sockets so i will make safe and they can iron out the other details!!
 

Rockingit

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listen "darkwood" ..... for your information kid i have 17th edition, 2391, PAT testing and my compex................. hope that doesnt sound too condesending pal.
Doesn't sound condescending at all. It sounds like you're a Electrical Trainee DI chancer, kid.
 
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nicsin02

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  • #29
Doesn't sound condescending at all. It sounds like you're a Electrical Trainee DI chancer, kid.
"Electrical Trainee DI" ???

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really are alot of big heads on this forum!
 

darkwood

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Wasn't trying to get your back up, and from your reply i assume this other electrician is part of your company too, if this is the case then do as you suggested but you have to be clear to the boss in doing so he should bring the job up to reg's as part of the work and not as a later thought, think of the senerio where you swap for spurs but couple of days later a serious injury/death happens because of a fault on say a computer; ok might sound like im been over dramatic but you last one to make changes and do you think your boss will take the fall cos i dont i think he throw the blame at your feet.

As goes my other comment pls understand we have to make a judgement call over the abilities and understanding that the OP has (yourself in this case) and sometimes we make a bad call but you questioning and replies suggested otherwise, it wasn't your original question that rang bells only your further replies to the posts so apologise if offended but did enjoy you 'KID' comment not often an old man (well 40) gets tagged with that.

If you check all the posts again you'll see im not the only one who came to the same conclusion but other well established members did too regarding the other issues brought up which do bare as much importance as to the safety of the circuit and require addressing at the same time.

I understand you time constraints and possible a boss who dosn't want to hear problems but just wants jobs done .... been there walked out but in your shoes id at least talk to your boss explaining you cant do what is ask of you without addressing the other issues at the same time, if he still tell you to get on with what you were asked to do then at least hes aware.... and as for this other electrician i hope he isn't part of your firm as he'd have been sacked for that level of work if i employed him.
 

darkwood

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"Electrical Trainee DI" ???

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really are alot of big heads on this forum!
Its not been bigheaded to explain to the OP that we believe the level of questioning he is asking should already be understood by him, as an electrician you should have an OSG (on site guide) with you and what is strange about your question is this is explained both clearly in word and picture form in both regs and OSG and dosn't give much room for mis-interpretation hence we questioned your level.
 
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Swicade

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  • #32
At the age of 41 I still wait in hope that one day when buying my ciggies the cashier will ask "are you old enough?" when the register beeps asking for age verification *sighs*.
 
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nicsin02

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  • #33
apoloigies if ive annoyed any1 2nite, too tired and going to have a crappy day at work tommorow, goodnight and peace
 

darkwood

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No worries Nicsin02 i personally dont get annoyed im too layed back, i wouldn't be on here for yrs if i got wound up, its a brilliant site for keeping my knowledge tweaked and yes i mess up sometime but take it on the chin ive asked and said some stupid things myself but been a regular i dont get away with it as easy they are like bloody vultures when against their own on here lol
 
[/QUOTE] it aint my job so the electrician who did it can take responibilty i will make safe as i can, and for your information kid i have 17th edition, 2391, PAT testing and my compex................. hope that doesnt sound too condesending pal.[/QUOTE]

Going from your pervious posts, you don`t sound to `competent`(Having the necessary ability, knowledge, or skill to do something successfully) to me.

If you are the last one working on that circuit then YOU are responsible for YOUR actions!
 
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nicsin02

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  • #37
it aint my job so the electrician who did it can take responibilty i will make safe as i can, and for your information kid i have 17th edition, 2391, PAT testing and my compex................. hope that doesnt sound too condesending pal.[/QUOTE]

Going from your pervious posts, you don`t sound to `competent`(Having the necessary ability, knowledge, or skill to do something successfully) to me.

timbobelfast get a grip!!!!!!

If you are the last one working on that circuit then YOU are responsible for YOUR actions![/QUOTE]
 
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shocking_eg

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  • #38
getting slightly heated here :p

either way, as soon as you start work on this installation it becomes your responsibility in some terms so make sure nothing is too dangerous as they will be looking at you thinking your the culprit !

good luck with the job, let us know how you get on fella ?

:)
 
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nicsin02

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  • #39
was on-site this morning never touched the circuit and recommended to other electrician that he changes spurs and wires an earth back too board, i will sleep easy
 
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shocking_eg

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  • #40
was on-site this morning never touched the circuit and recommended to other electrician that he changes spurs and wires an earth back too board, i will sleep easy
good mate, best keep clear of that one i think ! lol

worrying however by the current install you described, its surprising how much current a few pc's can pull and could probably easily overload those isolators ! :S

hopefully its rectified soon !
 

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