Busbar - 1.2MVA generator install

**mikeruss** · 19-05-2009

Hi all

I hope you can help.

In short:

I think I am being spun a line from my supplier.

I am contracting the installation of a 1.2MVA generator (outside the building), and my supplier is claiming new regulations stipulate a busbar must be used instead of the normal cabling to run to the building. Of course it's more expensive, bigger trench etc etc

It's a complicated relationship, and therefore difficult to get other suppliers involved.

The questions I have are:

Are there new regulations that stipulate a busbar must be used irrespective of generator output?

Assuming there are no reg changes

What is the maximum distance you can run cables before you need to use a busbar.
Is there a benefit to using a busbar over cable?

Thanks in advance.

**benji** · 20-05-2009

anymore info.ie.what would the length of the run be,what is the gen.feeding,what switchgear are you using and where is the switchgear
yours benji

**stretchyboy** · 20-05-2009

ditto benji, we need more info to see what the choices are.

Are you hoping to cable a long distance? would it need parralel feed cables and does this make the BB more viable?

I haven't heard of anything relating to a must for BB use in this situation

**rhyslittle** · 28-05-2010

Found some pretty useful info on diesel generators here at Generators for sale, Generators for rent, Power protection | Shenton Group

**tonynulty** · 29-05-2010

1.2 mega watt is a big generator, the current this generator can produce on 415volts is very very high, to carry a current like this will probably require a busbar system, if you try to carry this type of current in cables you may need to parralell 4 250mm cables up, or whatever, not good practice.

**davelerave** · 29-05-2010

ya what's the limit on number of paralleled cables?

**Lenny** · 29-05-2010

Fair play, that is a massive genset.....be worth a read of appendix 8 in ol' red should you go down this route.

**tonynulty** · 29-05-2010

I dont think there is a specified limit as long as the load is covered,but the problem is connecting at each end, if you use 4 250mm 4core cables, thats 16 connections 4 on each phase + neutral, almost impossible connecting depending on the size of termination box.

**tonynulty** · 29-05-2010

I dont think your supplier is giving you crap, its easier and better practice to carry this kind of load using busbars.

if you parralell cables up they all have to be fed from the same set of fuses or breakers, you cannot feed these cables from different switch fuses because if 1 set of fuses becomes tired and blows the other 3 cables will be trying to carry the load , cables will be overloaded