ELECSA Certification Scheme Elecsa assessment soon questions about EIC for job

[lucus]

HI

Ive got my assessment with elecsa soon and im hoping someone can help me out with a few questions, the senario i have is:

A Garden shed which is fedd from a ring main in the house, spured off into a un sw fused spur, then from there 2.5 armoured cable in to a metal clad RCD fuseboard in the shed, there is a lighting circuit and 2 sockets on a radial in the shed.

what i am wondering is how do i do the EIC for this instalation as i am unsure about it and really want to get it spot on for the assessment.

Thanks in advance i really hope someone can help me out

regards
Lucus

 

[IQ Electrical]

Was this your design?

When is the assessment?

 

[lucus]

hi

yes it was the only way really to get power to the shed

assessment is in 2 weeks

cheers

 

[lucus]

would you test the ring main on one schedule off test results incuding the submain supply, and then have a seperate schedule off test results for the shed C/U?

thanks for your help

 

[telectrix]

one question. is the ring main in the house RCD protected. if so, you then have 2 RCDs on the shed circuit, presumably with no discrimination. a fault in the shed could take out the house ring main.

 

[brizospark]

2.5mm seems a bit small

 

[lucus]

hi

yes there is 2 rcd's with no descrimination would this be a problem for the assessment?
also is the cable too small? if its protected why is it a problem?

regards

 

[malcolmsanford]

To be honest Lucus this is perhaps not the greatest install to show on an assement, the very fact that you have no discrimination becasue of using a spur off the ring final circuit proves bad design.

As you had used SWA you had no need to RCD protect it going out to the shed. So it could have either come of the unprotected side of the CU if you had one or you could have henly blocked the tails and fitted a small single board or a shower enclosure type board.

Also fitting a small board of a ring final via a FCU be it unswitched or not, is not a good design. You could have spurred direct off the ring final to the Shed into again a single enclosure with a 16amp protection device then to your sockets and then a FCU for the light, with a 3amp fuse.

As this is a shed what earthing supply have you? if it is TNC-S then did you get permission from the DNO to export the earth.

The size of the cable will depend on the run, as you have backed the cable with a 13 amp cartridge fuse. How far is the shed and did you do the calcs for load and volt drop.

 

[lucus]

thanks for your reply, this is in my own house which is the only reason i put a cu in the shed as it didt cost me alot, would you recommend that i run a seperate 2.5 twin from the main cu and put it on a 20a mcb and connect this to the armoured, then remove the rcd in the shed cu and put a main switch in its place, then use a 16amp mcb for the socket radial and keep the lights on a 6amp, as for the earth im using the tncs earth is there a requirement to ask them ive not heard about this before, would i be better to use a earth rod instead?

thanks for your help everyone its greatly appreciated.

lucus

 

[gpz900jim]

this install could catch you out, if i was you, try to find something else, as you have seen by the replies, you may have difficulties.

 

[lucus]

do you think i would still have problems even if i put it on its own feed direct from the house fuseboard on a 20a mcb and disconected from the fcu?

 

[lucus]

hi everyone
not long now until my assessment with elecsa, i have changed this instalation now, it is as follows:
20a mcb in house consumer unit rcd protected, 2.5 twin and earth to external enclosure, 2.5 armoured to a 2 way consumer unit, and from there there is a socket radial feeding 2 double sockets on a 16amp mcb and lighting on a 6amp mcb, so i have discrimination for fault protection, i have a rcd in the 2 way mains at present but am not sure if i should change this to a main switch so its only protected by the house rcd, as i wont have any discrimination with 2 rcd's.

any advice would be greatly appreciated

cheers

 

[telectrix]

easiet way is to replace the shed rcd with 2 pole isolator, but, is there any way you could feed from non-rcd section of the house CU?

 

[lucus]

the house cu is a small single rcd board it doesnt have a non rcd option, also the twin and earth comes down the corner of the inside wall so would need rcd protection anyway.
cheers

 

[telectrix]

the ideal situation would be to replace the existing CU with a new board. RCBOs for the house. 20A MCB for the shed. RCD and 2 MCBs in the shed. As you say, its a small board, so cost would not be excessive, and you would have made a major improvment to the house installation, and have a job to be proud of for assessment.

 

[Deleted member 26818]

Could he then use both the house and the shed as two separate jobs for assessment?

 

[sparkysmate]

Could he then use both the house and the shed as two separate jobs for assessment?

I think the answer to this is yes, as they are 2 seperate Jobs

 

[telectrix]

yep. that'll save a bit of diesel/petrol.

 

[tony mc]

Change the CU and use this as your assessement,if it is your first which I think it is, concentrate only on the CU change in your house.(You only need one job on 1st well I did unless it has changed)

The assessor is not there to test your design skills but to make sure you are SAFE and COMPETENT to carry out electrical work.

He or She will ask you to demonstate basic testing procedure ie PFC ZE or RCD trip times or even continuity of protective bonding conductors along with asking questions re knowledge of the BRB.(Basic)

They will look at you EIC & both schedules to make sure you are testing correctley and recording correctley.

You will find that the assessor is only human and they were in the same position at some time in their carreer and will know that you are apprehensive and uneasy.


The info from the forum members is spot on and that what this forum is all about.(IMO).



Good luck and post how you get on.

 

[lucus]

hi
surely the shed feed would still need rcd protection from the board as the cable is a normal pvc twin and earth conceled within the wall down a corner, it is less than 50mm can someone correct me if im wrong

cheers everyone for the help.