Table 41.1 and Reg 411.3.2.2

[SgtTrojan]

Ayup chaps,

Would you be bale to confirm this for me please?

Quoting the red bible.

411.3.2.2 - (Table 41.1 TN system) Any final circuit at 230v not exceeding 32A must disconnect in 0.4s.
411.3.2.3 A TN circuit can disconnect upto 5s as long as it is a distribution circuit or exceeds 32A.

Therefore.. does the 17th no longer recognise fixed equipment/ portable equipment? That being said.. lighting circuits now have to diconnect in 0.4 seconds?

confused.com

 

[NotHimAgain]

Ayup chaps,
Therefore.. does the 17th no longer recognise fixed equipment/ portable equipment? That being said.. lighting circuits now have to diconnect in 0.4 seconds?

Well it is true to say that it no longer uses those distinctions for this aspect of shock protection.

This is a significant improvement because it removes the (hard to defend) situation where a portable hand held appliance would have to disconnect within 0.4 seconds, but a hand gripped fixed appliance (a lathe for example) would not. However, the decline in the use of fuses for final circuits has done much to make these distinction irrelevant in most installations.

 

[holmslaw]

..

 

[NotHimAgain]

The nominal supply voltage in the UK is 230 volts.

 

[holmslaw]

..

 

[NotHimAgain]

I repeat - the nominal supply voltage in the UK is 230 volts.

This is a matter of European harmonisation - it would breach an EU Directive if it were not.

Look here under amendment 4

http://www.opsi.gov.uk/si/si1994/Uksi_19943021_en_1.htm

Now the voltage at your house could be 240V or even 250V that does not matter - the nominal voltage is 230V.

 

[SgtTrojan]

Yeah, I am assuming we are still required to use the 230 column hence, 0.4s.

Well... this could mean having to put lighting circuits, immersion heaters and fused spur radial circuits on RCDs to achieve the 40ms trip time?

 

[plugwash]

Assuming you are using type B or C MCBs .4s vs 5s disconnect time will make virtually no difference at all. To get under 5s you need to hit the fast trip and once you hit the fast trip the MCB will disconnect extremely quickly (.1s iirc)

 

[SgtTrojan]

Or if they are fuses to achieve the 0.4s the max. Zs should not exceed 41.2 values?

Crikey..

 

[17thman]

I think what Gareth might be getting at is or i am getting at is what is the use of table 41.4 for the 6A thru 32A columns.

 

[17thman]

by the way, team fortress 2 is better.

 

[SgtTrojan]

Aye, that's what I was thinking.. but then you could supply a 2 way unit for a couple of daft lighting circuits off a 6 amp fuse I suppose?
Then that being classed as a distribution circuit it can take upto 5s to trip.

 

[SgtTrojan]

TF2 :O I've seen the vids.. looks like fun. I am CS 1.6 all the way though dude. (Head admin of britishsergeantsmess.com)

 

[17thman]

true

 

[SgtTrojan]

So the big question is...

Why did they change it?