Garage enclosure

[Mewff91]

Hi all,

Rewired my dads garage today for my part p assessment, i bought an enclosure and a 16amp and 6 amp mcbs for the circuits within the garage. The enclosure only had the din rail in. No earth or neutral bars. The garage is fed from a 32amp mcb from the cu in the house by 2.5 mm cable which is rcd protected. The problem i have is that i have no incommer. Ive seen the garage boards you can get with a main rcd as the incommer but my dad wants the rcd in the house so he knows it has triped if it does!

Seems silly but i feel that a 100a incomer would be too high rating wouldnt it?

Ive got an earthing block which i will fit into the cu for the cpcs of the circuits and i will do the same for the neutrals.

 

[Strima]

No neutral or earth bars? What make is the enclosure?

As for the 2.5 protected by a 32A??? What type of cable is it?

 

[electric will]

You've been given a 2 module enclosure and not a garage board, this is no good to you, also your 2.5mm cable is under sized, even if swa max is 31 amp is xple (I think)

 

[robsparky1975]

I would change the breaker for a lower rating,is it swa feeding the garage? ask yourself would you want your assesment job to be one where you have had to put something together? you can buy a 2 way garage board with a main switch and 2 cbs for about £30.

 

[electric will]

Also def have swa unprotected in house cu as assessor will have you do rcd test in garage, wouldn't be good if you kept tripping house rcd during tests, also no discrimination

 

[Des 56]

As rob as stated,cobbling a board together for an assessment would be not the wisest move
An assessment candidates "show jobs" are mostly done to his best installation skill,an assessor would be unimpressed by a less than top notch effort
Don't undermine your assessment this way

 

[Jimmy Boy]

What is the supply from the house ? TNS/TNCS ? Garages have lots of wonderful things in them
J

 

[Mewff91]

Thanks for the feedback guys!
Cable is 2.5 twin earth, and runs through the ceiling joists in the house straight into the garage.

I will also be doing a cu change in the house so will downsive there.

Think ill just get a garage enclosure like you said with the rcd in the garage!

Thanks for the help guys!

 

[telectrix]

yep, protect that 2.5mm at 20A, if part of it's buried in a wall < 50mm without earthed metallic conduit protection, then RCBO it. then no need for RCD in garage. don't forget if there are extraneous metal parts in the garage, these will have to be bonded back to the MET. in 10mm if it's a TNC-S installation.

 

[Mewff91]

Thanks tel! No extraneous metal parts within the garage.
With an rcbo in the house though if have to remove the rcd from the garage board, if i get one because of discrimination?
Just use a main switch then yes?
Sorry guys just want it to be top notch for the assessment

 

[sedgy34]

yep, protect that 2.5mm at 20A, if part of it's buried in a wall < 50mm without earthed metallic conduit protection, then RCBO it. then no need for RCD in garage. don't forget if there are extraneous metal parts in the garage, these will have to be bonded back to the MET. in 10mm if it's a TNC-S installation.

Tel there's no pme export here or have I missed something

 

[telectrix]

Thanks tel! No extraneous metal parts within the garage.
With an rcbo in the house though if have to remove the rcd from the garage board, if i get one because of discrimination?
Just use a main switch then yes?
Sorry guys just want it to be top notch for the assessment

. yes, you don't want RCDs in series because of discrimination. just use a D/P main switch in the garage. anything from 40A to 100A ( it's just a switch, the current rating is the max. it will stand).

@ sedgy, i assumed it was a TN system, probably PME, OP has not said as yet. but as no ecp's then it 's irrelevant anyway.

 

[telectrix]

1 other thing. the cpc in that 2.5mm is only 1.5mm, so measure the PEFC and apply the adiabatic. you still might have to add an additional cpc.

 

[Mewff91]

Cheers tel!
Sorry thought i put it in its tncs guys.

 

[Jimmy Boy]

typo sod it

 

[electric will]

Due to the twin and earth only having 1.5mm cpc wouldn't it be easier for him to rid the garage and tt it, rcd as main switch obviously?

 

[Strima]

rcd as main switch obviously?

Unless there is an RCD at the source of the distribution circuit???

 

[electric will]

Yeah was thinking the distribution circuit would be best unprotected but it's twin and earth, not always possible, still tt sounds good though?

 

[Strima]

Search for a thread on here about exporting PME, very handy to know.

 

[electric will]

Reason for me suggesting tt wasn't really to do with exposed conductive parts etc, more to do with a earth cable needing to be run aside the supply twin and earth, if bigger cpc neededm thought it'd look untidy, think op said it'd be clipped to fench. Now what about damage from uv rays? Sometimes you can ind a reg that'd stop you doing anything.