Board Change

[m4tty]

Hi,

If you went to someones house to do a board change from BS3036 Rewirables to 17th Ed CU and noticed loads of non-compliences ie. garage wired in radial from 32A breaker in 2.5mm singles and all garage electrics were a bodge. Do you have to sort out the non-compliences whilst you are there or can you change the board and note non-compliences on cert.

Thanks

 

[Andy™]

if there are dangerous (i.e would be a code 1) then they wont get reconnected. anything else safe, but not to standards is marked on EIC make sure you state in T&C's that any dangerous circuits will not be connected

 

[ian932]

Hi,If you went to someones house to do a board change from BS3036 Rewirables to 17th Ed CU and noticed loads of non-compliences ie. garage wired in radial from 32A breaker in 2.5mm singles and all garage electrics were a bodge. Do you have to sort out the non-compliences whilst you are there or can you change the board and note non-compliences on cert.

Thanks

Its unlikely that all existing circuits will comply, 7671 say

 

[spinlondon]

The EIC has a space for noting defects in the existing installation.

How is the 32A breaker for the garage fed?

Simply changing the CU from re-wireables to MCBs does not necessarily mean the installation is safer.

Some MCBs have a lower maximum allowable Zs than re-wireables.

 

[m4tty]

Presently BS3036 Rewirable with 2.5mm singles run under garden path in plastic conduit. Garage about 200ft away from house. Been like it since 1970. In garage is Lathe, Medium sized Compressor, Welder & Lighting. When compressor starts up lights dim. Bad but 'works' lol

 

[spinlondon]

I'm Assuming that you are saying the Garage is fed from the CU.

If so, then you would be expected to use the correct rating of MCB to protect the cable, and then note any defects on the EIC.

 

[Andy™]

60+ mtr of 2.5 and a welder/compressor..... must be about 120V at the end!

 

[ian932]

Simply changing the CU from re-wireables to MCBs does not necessarily mean the installation is safer.

He is not just changing from 3036 to MCB there will be RCD's too

Some MCBs have a lower maximum allowable Zs than re-wireables.

Can you expand on that one please?

 

[Andy™]

Can you expand on that one please?

5A 3036 - 9.58

6A 60898 - 7.67

its all in the BRB

 

[ian932]

[quote name='Andy

 

[Andy™]

Cheers Andy I knew that, I was trying to establish what point spinlondon was trying to make.

the point of changing a 3036 to 60898 with a high earth loop means youve made something that did comply, now not comply. so you cant say youve left it safer than it was

 

[sarni31]

but as the 17th edition board will be RCD protected the zs becomes less important to 1667 ohms

Guinness

 

[Andy™]

what if its not in a house and doesnt need RCD'd?

 

[sarni31]

I understand it to be more down to the type of person using the installation...

shed

garage

house

unit

warehouse

factory .....

inside or outside ....

skilled, supervised, ordinary?

as to use an RCD or not

Guinness

 

[ian932]

[quote name='Andy

 

[sarni31]

as you say Ian

20A for garage shed

dual RCD protected consumer is safer (in this instance)than the bs3036 consumer due to both quicker disconnection times and the additional protection by rcds

Any deviations from the big red book ...

note down in the Deviations section of the cert .. thats what its for, you can't make customers rewire their property to suit BS7671.

Guinness

 

[m4tty]

[quote name='Andy

 

[Andy™]

did you measured the voltage at the end with the load applied (i.e compressor etc on?)

 

[safedepth]

Voltage fluctuates constantly Matty. 241 or 236, it matters little, regarding volt drop, with no load you will have no voltage drop. BRB Table 4D1B.

 

[m4tty]

Thanks for the replies, yeah hand up I measured it with no load ffs. sorry.

Im trying to work out VoltDrop using calculation. Can someone tell me if im doing the calculation properly Thanks

2.5mm Line & 2.5mm CPC (as wired in singles)

(14.82 x 30A x 60m) / 1000 equals 26.676v

Ive used 30A as thats what fuse its on (i know it should be dropped to 20A as 2.5mm cable) but is this the right way to work it out. Obviously it fails the 5% allowed

Thanks again for helping me understand

Matt