crazy voltage

[bethelec]

testing sockets in a school classroom (new installation) and had a reading of 196volts. Went back an hour or so later and had 240 volts. Tested another circuit which was on the same phase and had 196 volts again. All phases to earth and neutral read 245v and fuse board. All I can think is a possible loose connection on the supply busbar. Could anyone else shed a bit of an idea. Thanks

 

[rallyandy]

was thinking the same, sounds like a loose or dirty connection somewhere

 

[telectrix]

as you say, sounds like the fault is on or around busbar, but also could be on the incomer of the affected phase, even on it.s cut-out fuse or meter tails.

 

[RWJ]

Are the sockets in a lab using (Blakley Unit)??? ..... Just throwing in ideas!

 

[bethelec]

it is a new installation so no load on the sockets as yet

 

[Superspark23]

Test L-E then L-N if the 196v returns on both then you have a loose live, on L-E then you have a loose earth likewise for neutral

 

[fire]

this could be a loose connection but being a sub station worker, i think the origin of this problem could be the local sub station. there was probably a surge in demand and the transfomer at the sub station didnt tap into the widdings to increase the voltage.