Hi folks, I've got a customer who has rented a farm unit and used it as a joinery shop for about 9 years the supply is 60/80 amp three phase underground service, from a pole mounted transformer about 200m away, the transformer also supplies a farm house via an underground supply, these are the only buildings off the transformer.

The supply is also sub metered to a a joining unit that has been up to now used as storage, however now a car alarm installation company have the unit, the loading on this is low with no car ramps or air con units and at the time just one 2kw panel heater. The lighting in the car workshop are low bays.

The problem is when my customer starts up a planing machine the low bays go out and some of the fluorescent tubes dim.

I want to look at this about 8 weeks ago and found that even when a small chop saw that a chippy would use of site was started the lights flickered.

My first thought was a loose connection, but due to the fact I could not isolate much at the time I tired another method which was to go into the farm house and test the voltage as loads were added in the work shop, my MFT which is in calibration registered 197 volts with a 45amp load across three phases in the workshop, the load without any machines running is 20amp per phase, remember this is a separate service off the same transformer.


I then at the joinery shop incomer carried out a loop test which was all fine.

The motor that seems to cause the problems has a 6 kw start up current which is a bit of a spike but not massive, even without this the voltage heads south with every another thing is switched on.

UKPN were called in and fitted logging equipment at the service head, the customer told me after a week they returned and found it was not working as it had been installed incorrectly, it was then refitted and they seem to think its within the limits it should be.

I'm intending to return with a number of heaters and my spare testers to double check the voltage to load it up to about 50 amps per phase.

Naturally the transformer is in the usual asset managed condition, in a field on a pole leaning at 40 degrees is stained black around the bushings with oil that's run down it, also the customer told me two lv fuse holders burn out in the last five years one causing a small fire.

I don't know the rating of the TX but its the biggest you could fit on a single pole.

UKPN have told the customer he needs to pay for a supply upgrade which i think is totally unnecessary, what do you think?