John Chung wrote:

>One of the fuse on my MCB is causing the main circuit
>breaker to trip.
>
Is this your home or shop main circuit box you are talking about.  is 
the main CB a GFI type?
It is VERY unusual to see this. Against code in some places.

>Here is the problem. The *fuse* to
>the gate can be turned on for about 15 mins. After
>that the main circuit breaker trips. I hooked off the
>live and neutral wires from the auto gate box. Still
>trip immediately after I switch on again. So I gave a
>cool down period of 4 hours again. The same cycle
>happens.
>  
>
another problem might be The total current draw on each circuit is not 
enough to trip their own breaker or fuse but the total of all circuit 
will trip the main CB.
example 18 circuits each having a 15 amp CB  the main CB is 100 Amp. 
Just 12 circiuts drawing 8 or 9 amps each will total 96 to 108 amps and 
cause the main CB to trip. being it is warm  it will trip again if you 
try to reset it right away.  If you wait for it to cool and then reset 
it, the process will start over. 
 

>There are 2 possibility that I have accounted for.
>1) The wiring to the GATE to faulty! Still can't
>explain the 15 mins delay....
>2) The fuse switch to the gate is faulty! 15 mins
>delay? Not sure on this.
>
>I don't have any other possible clues.
>Guys do you have any other suggestion?
>
>John
>
>
> 
>____________________________________________________________________________________
>Never Miss an Email
>Stay connected with Yahoo! Mail on your mobile.  Get started!
>http://mobile.yahoo.com/services?promote=mail
>  
>

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist