Bus Bar Chamber

[THE FLUTE]

Been doing some work today at a site and the 2 electricians that work at the place are putting in a new. Busbar Chamber for some machines.
They have come from the main switch with some 70mm swa into a Fused switch and into the chamber with some 70mm TRI rated. All looks good. I then notice the fisrt set of cables they have taken off into a 63Amp switch fuse are only 25mm off the bus bar. Now I am missing something here as when ever I have done one I have used the same size cable to every out going switch as the cable must be rated to 160amp?? :tounge_smile:

 

[MDJ]

16mm2 would probably be big enough, I am suprised they installed 25mm2 to be honest as the switch is 63 amp rated and directly connected to the Busbar.

 

[Pete999]

How far away is the 63Amp Switch Fuse?

 

[MDJ]

How far away is the 63Amp Switch Fuse?

Good question pete I may have slipped up here, I assumed it was bolted to the Busbar, I suppose I shouldn't of.

 

[MDJ]

Now I am missing something here as when ever I have done one I have used the same size cable to every out going switch as the cable must be rated to 160amp?? :tounge_smile:

So how would you get 70mm2 cables into a 20 amp red Fire alarm switch fuse then? they are quite commonly bolted onto Busbar Chambers, you may well break the guinness book of records if you can manage that.

 

[Pete999]

Have a butchers at 434.2.1

 

[Plonker 3]

been lots of discussion on this lately, reg 434.2.1 covers this.

 

[MDJ]

Have a butchers at 434.2.1

Me or the OP???

 

[Pete999]

Me or the OP???

Sorry mate the OP LOL

 

[THE FLUTE]

Have a butchers at 434.2.1

Thanks for the Helpfull advice Just read that regs

 

[MDJ]

Was hoping you could explain your comment in post 1 regarding the fact you said and I quote "when ever I have done one I have used the same size cable to every out going switch as the cable must be rated to 160amp??" Seems kind of strange IMO, as the majority of switch fuses under 160 amps will be difficult to get 70mm2 tails in, Even a 100 amp switch fuse can be awkward with 50mm2 tails, unless it takes lugs rather than has connector pots, so a 63 would be impossible, was hoping for some clarification from you fella.

 

[MDJ]

:waving: still waiting

 

[THE FLUTE]

Sorry in Isle of Man getting ready for this years TT so not been on here.
I must be getting confused then its been a while since i did any bus car chambers. And can never remember fitting any thing less than 100amp stuff on to them. I was just thinking about the short or fault current on the cable. But guess over such a short cable run it will be fine.

 

[Engineer54]

You're basically allowed 3 meters, before needing to meet rating of cable supplying the bus bar. Assuming that everything else is in compliance!!