Strange PIR today.....

[Crosswire]

OK, so went to do a PIR on a pub today. Had a 3 phase supply head and board, but only 2 of the phases were used.

However, the yellow/black phase was used twice - i.e. there were two 25 mm cables in the yellow/phase of the supply head, and none in the blue/black

The subsequent boards were treated as 3 phase boards, and were identified as such with regards to colours of the phase tape on the tails.

In my opinion this must have been a mistake by the meter man, but my question is this....


How do I code this as a fault? All I can think of is 'incorrectly identified phases'...

Are 'two phase' boards acceptable?

Any thoughts?

 

[needasparks]

Two phase supplies are quite common. Don't think i've come across a three phase board with it though only two separate single phase jobs. Are you saying two phases are linked at the main switch to use the spare last phase in the board ?

Some installs only have two phases available and may not be a true 120degs and be 180degs from each other.

 

[Crosswire]

Phases not linked at switch , rather, instead of one 25mm double insulated tail in each BS1361 fuse on the supply head, there is one in the red/brown phase, two in the yellow/black phase, and none in the blue/black phase.

From there on in all switchgear and boards are of standard arrangement, i.e. treated and wired as a standard 3 phase board, and identified as such.

It seems no-one has noticed that the three phase board is in reality a '2 phase board' !


Took photos on phone but can't upload to forum cos I'm too thick:blush5:

 

[needasparks]

Does sound more like what i said, I don't think a meter installer makes that kind of mistake. same rules apply to the install as three phase though for the purpose of testing.

edit
should of asked, is this install out in the sticks by any chance ?

 

[Guest55]

How do I code this as a fault? All I can think of is 'incorrectly identified phases'...

Are 'two phase' boards acceptable?

Any thoughts?

Unbalanced loading of the installation springs to mind.
Plus if the yellow / black phase goes down they'll lose 66% of their circuits instead of just 33%.
As for 2 phase boards being acceptable , well no more dangerous than 1 or 3 ph boards if approached with the same level of caution.
But i'd want to acertain with the meter fitting outfit that their connections are correct , you can be fairly certain the unused phase is active / live.
Carry out your PIR as normal and make a note of it in the report , wouldnt give it a code though as its part of the suppliers wiring.
Oh and hi all

 

[Crosswire]

Not in sticks, inner London believe it or not !

 

[plugsandsparks]

Assume there are no TP devices being used and its all single phase. Would be interested if the blue/grey phase is actually lit at the head end and i would expect you would not get correct phase rotation at any of the boards.
So you could code as incorrect iedntification of conductors, i.e. no blues or greys in reality, you could also code the TP rotation just in case he thinks he has a regular TP supply and tries to connect a big chip fryer up.
In any case if the blue/grey phase is lit - this could be a recommendation to use it. BUT this does seam very odd, Also might be worth just checking the neutral for any over-heating

 

[Knobhead]

Read this and didn’t think much of it and wandered off. But then thought “wonder what’s gone on in the past?”
OK this is a wild shot but at some time in the past a phase could have gone down and as a quick fix the DNO have just doubled up on one phase. As is usual “if it’s working, forget it”. There’s probably a ten year old work order for remedial work to be done by the DNO at the bottom of a pile of paper.
The danger is the neutral getting toasted.