This is about a garage.

[Seanisok]

Hello Ladies and Gents.

Apologies in advanced, i doubt my self a little too much.

I have ripped the old fused bored of the wall, pulled the cables out. Well, 2 reasons. I have NAPIT coming around to assess me and Its definitely a job that needed doing... A rewire I mean, of the garage.

I am going to reuse the supply cable - 2.5mm 2 core SWA, about 13 meters long - I have tested it an yet it might be old as the hills but its in good condition. Plus it buried and there is a patio. I really want to use it.

So i have decided that there will only ever be a maximum load of 3.5Kw - There is a dryer in it. Buried conditions. I cant tell if its 70 degree Celsius or 90 thermoplastic, so i did the math to 70 - if it every gets to 70 degree Celsius the Zs will approx 0.96 The RCD 20 Amp 80% Max Zs is 1.75Ohms

Ref Method D for that cable is 29 Amps a ambient temp of 30, i think, of the top of my head.

the post is really about this next bit

I have wrote EIC for the supply, stating exactly what I'm doing and what I'm not doing. I have wrote Schedule Of Inspections for new works. 2 Schedule of Test Results, one for the sub main feed to the garage and one for the garage electrics.

does all that sound alright?

cheers guys

 

[telectrix]

if the cable is SWA and buried direct (no ducting) you an add approx. 10% to the ccc. and always work to 70 deg. as even if the cable itself is rated to 90, the gear it's terminated into will generally be 70.

 

[Dartlec]

That all sounds reasonable to me. Though if you haven't altered the OCPD at the source, or touched the cable, then the EIC perhaps only needs to cover the new work in the garage though nothing wrong with adding more information and additional testing, just be clear in the "extent of installation work" what you've done and not done (sounds like you have that covered)

It does still need to be assessed as suitable for the load, etc of course - and since you are being assessed on it, then I would print out a copy of any calculations you've done to confirm that - it will show a thorough approach to the job.

One other thought since this sounds like a detached garage- Is the supply PME? If so have you verified that there is no need for bonding of any extraneous parts in the garage? Armour on 2.5 SWA wouldn't meet requirements for either PME or TN-S so hopefully it's not an issue - but something to be aware of so you can answer confidently if the question is raised.

 

[Seanisok]

if the cable is SWA and buried direct (no ducting) you an add approx. 10% to the ccc. and always work to 70 deg. as even if the cable itself is rated to 90, the gear it's terminated into will generally be 70.

Thanks you for the information Telectrix

 

[Seanisok]

That all sounds reasonable to me. Though if you haven't altered the OCPD at the source, or touched the cable, then the EIC perhaps only needs to cover the new work in the garage though nothing wrong with adding more information and additional testing, just be clear in the "extent of installation work" what you've done and not done (sounds like you have that covered)

It does still need to be assessed as suitable for the load, etc of course - and since you are being assessed on it, then I would print out a copy of any calculations you've done to confirm that - it will show a thorough approach to the job.

One other thought since this sounds like a detached garage- Is the supply PME? If so have you verified that there is no need for bonding of any extraneous parts in the garage? Armour on 2.5 SWA wouldn't meet requirements for either PME or TN-S so hopefully it's not an issue - but something to be aware of so you can answer confidently if the question is raised.

Hi Dartlec

I have done all the maths on paper, following your advice I'll definitely put them in the folder with the test certs for the day I'm assessed along with a few brand new ten pound notes... I have not actually altered anything from source, I'm content that particular circuit OCPD is suitable. The garage is feed is terminated onto 20A MCB and a 30mA RCD. The supply to the House is PME and I have no extraneous parts in or near the garage. I think I might just get away with the SWA fingers crossed.

Thank you for they bringing up the bonding, I feel like I have some extra ammo now.

cheers