3 Phase query - help!!

[polo1]

Ashamed to admit, but my 3 phase experience is limited:blush2:

What would cause me to loose the indication of a phase, when applying a load to that particular phase? It only happens with certain loads.

Thanks.

 

[harristeve]

Hi
Is it 3 Phase only or 3 phase and neutral?
And how are you testing it?

 

[polo1]

Sorry, first post was kinda rushed. 3P & N.
I've been getting pulled all over the place on this job and not getting time to do anything properly/methodically.

"Testing" has been simply checking phase to N. When load is applied phase appears to drop out. It's a sub board, serving three lighting and one other (unidentified) circuit and I have not yet found out where it's fed from. A thought, could this be voltage drop, as the sub main appears to be quite small?

 

[oxocube]

Seems like a loose connection, its good enough to give the indication, but when a heavy load is applied the connection cannot carry the current.

 

[telectrix]

Seems like a loose connection, its good enough to give the indication, but when a heavy load is applied the connection cannot carry the current.

agree. cherchez la loose screw

 

[harristeve]

hi
Also check the neutral as this could be causing you a problem. :17:

 

[Knobhead]

hi
Also check the neutral as this could be causing you a problem. :17:

The fault was sorted yesterday.
Our OP posted a duplicate thread, naughty boy!