MCB's

[apprentice87]

Hi All,

Does it matter "which way round" you wire an MCB?? in other words, does it matter which you use as load or line side??

If the thing is marked "line" and "load" it would be obvious, same if the terminals were numbered, but most of then have no marking at all..

Reason for asking, is that i would, left to my own devices, wire all fuses or MCB's with the bottom end as line and the top as load, just seems sensible to me, but i have seen some MCB's with terminal markings that mean they are intended to be fed from the top, what you all usually do???? Do they vary??

john...

 

[NozSpark]

Well, most single phase db's have the supply at the bottom of the mcb whereas mcbs designed for three phase db's have the supply at the "top".

But they usually aren't sensitive to which way they are connected.

 

[M107]

Load to the top as most single phase cu's are made with the busbar along the bottom.............but I dont suppose if you say had an mcb inline of a conductor then it makes no difference which way you connect it, might be adviseable to label as load & supply though

Bloody hell Noz that was quick mate.

 

[NozSpark]

Just beat you to it mate

 

[kerching]

Well I am not sure if it is Hager or Dorman Smith but, on one of their 3 phase boards you HAVE to fit the MCB the wrong way around to make the darned thing fit [there is even a sticker in the board to tell you just that............ :coat

 

[apprentice87]

Thanks all, I was just wondering what you would all do if just sticking one in an enclosure on its own. I would feed it from the bottom, as i guess that is what most people are used to, unless of course the makers have printed terminal numbers on it that say it goes the other way up, bit like this one!!

View attachment 2876

john..

 

[steptoe]

and, some MG boards have the busbar at the top, but, they are odd-ball thingies and I dont think other MCBs fit.