busbar theoretical....

[ColJack]

if you feed a busbar ( the type for linking breakers together in a panel ) from the center intead of one end, does that double it's rating?

if for example a 63A busbar had 100A worth of breakers ( 5 x 20A breakers for arguments sake ) and was fed form one end, in theory you will be pulling 80A through the busbar at the feed end if the breakers were all loaded to capacity ( 4 x 20A remaining, the first breaker wouldn't draw current through the busbar )
if you feed it from the middle then you would have 40A each side ( again the breaker being fed wouldn't draw through the busbar, so 2 x 20A each side )

 

[plugwash]

From an electrical theory point of view what you say is correct provided the arrangements at the point of feeding into the busbar can safely handle the currents. How it would relate to regs I have no idea.

 

[ricicle]

Yes you can. Our old factory was designed so that the 400A busbars were fed in the centre via 800A supplies. The only possible problem being that you could overload the one half if too much equipment were plugged in but that is why us competants were there to stop such occurences

 

[Lectrician]

You would need to consider how you fed it into the middle.

 

[holmslaw]

..

 

[ricicle]

Forgot to mention, I was talking about overhead busbars !

 

[vsynth]

Yes you can. Our old factory was designed so that the 400A busbars were fed in the centre via 800A supplies. The only possible problem being that you could overload the one half if too much equipment were plugged in but that is why us competants were there to stop such occurences

I would suggest that the answer is no since unless people like you are on hand to oversee that the load is balanced we could have a fire on our hands.

 

[wingcoax]

I would hope that the incoming circuit breaker (as well as the others) would have an overload protection device fitted. This would obviate the need for constant monitoring and give protection

 

[Spark123]

If it was possible to physically cut it in half safely I don't see why you couldn't class each half as being able to carry FLC.

 

[Stoday]

Hey you could then have a real ring main, one leg from one busbar and one from the other.

Of course, real ring mains are always operated with an open point somewhere.

 

[Lectrician]

Most TPN boards are available in 125 and 250 amp versions. If you look at where you fit the incomer, on the 125amp boards there is a single piece of copper busbar, and on the 250amp there is two pieces. I am not sure if the two busbars are also jointed elsewhere in the assembly or if they rely on the load being shared equally.