short circuit capactiy bs3871 type 2

[Strickers]

could anyone help me with the short circuit capacity and maximum permitted zs of a BS3871 type 2 MCB please. And if using the sheath on a micc cable as cpc what do you put in the cpc mm2, is putting sheath acceptable.

Thanks Paul

 

[sparkylad]

It depends on the rating of the CB.

 

[Sintra]

Short circuit capacity

There should be an M number on the MCB

M1 1000A
M1.5 1500A
M3 3000A
M4.5 4500A
M6 6000A
M9 9000A

Have a look here

http://www.beamainstallation.org.uk/assets/pdfs/CircuitBreaker.pdf

 

[scotsparky]

Page 102 of OSG has a great table on it showing max ZS MCBs

 

[sparkylad]

Keep in mind though that these are the adjusted values and not the values to be entered on certs.

 

[Guest123]

And if using the sheath on a micc cable as cpc what do you put in the cpc mm2, is putting sheath acceptable.

Thanks Paul

Cross sectional area in mm squared of regular MICC.

Effective area of cable sheath......

2L1 ****** 5.4 mm2
3L1 ****** 6.7mm2

2L1.5 ****** 6.3 mm2
3L1.5 ****** 7.8 mm2
4L1.5 ****** 9.1 mm2


2H1.5 ****** 11 mm2
3H1.5 ****** 12 mm2
4H1.5 ****** 14 mm2


2L2.5 ****** 8.2 mm2
3L2.5 ****** 9.5 mm2
4L2.5 ****** 11 mm2

2H2.5 ****** 13 mm2
3H2.5 ****** 14 mm2
4H2.5 ****** 16 mm2

2L4 ****** 11 mm2
2H4 ****** 16 mm2

2H6 ****** 18 mm2
3H6 ****** 20 mm2

2H10 ****** 24mm2
3H10 ****** 27mm2

2H16 ****** 30mm2
3H16 ****** 34mm2

 

[Strickers]

Thanks for your advice everyone i've got all the information i need. I know this might sound bit weird but has anyone got a old 15th edition im doing quite a bit of testing and might be of use.

 

[scotsparky]

15th?? remember when your testing it to CURRENT regulations the 15th are 20 years old.

 

[sparkylad]

Ive got a copy of its Daddy. The 14th Edition.........only a keepsake now though

 

[Strickers]

Im aware that were testing to the 17th edition doesn't mean that all earth loop values for old mcb's will be in the 17th.

 

[Sintra]

Also when doing a PIR you still need to know if the installation meets the standards of the edition to which it was wired.

So an installation wired and complying to the 15th edition would be perfectly satisfactory you would only have to note the items that do not comply to the current edition as code 4.

It might be worth trying to source one if you do PIR's.

 

[pevvers]

Also when doing a PIR you still need to know if the installation meets the standards of the edition to which it was wired.

So if you found a building wired to the 1st edition, would you be saying that you would only put code 4's down?

I know that's a bit extreme, but in essence that's what your argument is, no?

 

[Sintra]

Hopefully an installation done in 1888 would be out of comission by now but you could still have fully servicable and compliant installations to the 14th & 15th editions which can not be deemed unsatisfactory just because there is a newer addition to the regs.


Take for example a 16th edition installation installed in 2005 and due it's 1st periodic now. This installation will not have all socket outlets RCD protected nor will it have RCD protection on all circuits in bath / shower rooms etc. but the installation can still be satisfactory.


All opinions welcome.

 

[scotsparky]

Im aware that were testing to the 17th edition doesn't mean that all earth loop values for old mcb's will be in the 17th.

there in OSG page 102 and ther the 80% correction has been applied.

 

[pevvers]

Hopefully an installation done in 1888 would be out of comission by now but you could still have fully servicable and compliant installations to the 14th & 15th editions which can not be deemed unsatisfactory just because there is a newer addition to the regs.


Take for example a 16th edition installation installed in 2005 and due it's 1st periodic now. This installation will not have all socket outlets RCD protected nor will it have RCD protection on all circuits in bath / shower rooms etc. but the installation can still be satisfactory.


All opinions welcome.

So would you be happy with a fused neutral, as it was compliant with the regulations at the time of construction?

Or no RCDs on socket outlets that are likely to supply portable equipment outside the equipotential zone? A requirement for quite a while, and all the big players agree that it is a code 2, but there are enough BS3036 boxes out there with no RCD protection.

Just a few thoughts!

(I like to chat me, )