Random voltage/Power loss

[Shorne]

Hello everyone I am a new member to this and was wondering if anyone can help.

We have a client at a pub that randomly loses power to several circuits for about 2 seconds, then comes back on. We are trying to establish whether the problem is coming from the incoming supply or a sub circuit. The electrical suppliers are saying that the problem is not on the incoming supply , is there any tests I can do to establish why and where they are having this?

Thanks

 

[westward10]

Sounds like a loose connection. If you are losing several circuits sounds like it maybe within a dist board.

 

[telectrix]

first your visual tests. check all terminations applicable to the suspect circuit/s. then it's logical sequence of dead testing followed by live testing, as in the book/s.

 

[Shorne]

The problem is that it's not just one final circuit that loses power, its several and its random.

Also the problem is coming from 2 separate fuseboards. We have done visual checks. We originally found one fuseboard had internal busbar damage which we have since replaced but the problem still persists.

It's so random that they could go days without anything happening.

 

[Andy-1960]

Is it a 3 phase supply?

 

[Specialist]

The problem is that it's not just one final circuit that loses power, its several and its random.

Also the problem is coming from 2 separate fuseboards. We have done visual checks. We originally found one fuseboard had internal busbar damage which we have since replaced but the problem still persists.

It's so random that they could go days without anything happening.

Is it just random circuits or a whole Dis board that drops out ?.

 

[Pete999]

Get an EICR done, any loose connections bad wiring should be higlighted

 

[Shorne]

It's just random circuits, but varies each time it happens. It's racking my brains, thinking of getting a voltage logger set up

 

[Octopus]

I think the clue is "at a pub" - pubs are notorious for carp electrical installations..... best get some more facts..... but the basic checks on live and neutral connections would make sense........

 

[Specialist]

If the faults are that random then a voltage logger won't do much good, what circuits would you connect to ?

As Murdoch said, pub wiring is notorious. Especially if a brewery in house job.

 

[telectrix]

go in with an open mind, set an hourly rate of 3 pints per hour. all will soon become crystal blurred.

 

[Specialist]

You forgot food tel, but at that rate I'll meet you there

 

[Shorne]

I'm thinking of putting voltage logger at main incomer i.e supply side of main switch to see if any issues at source. Asked UKPN to come out to set this up but that could be other side of Christmas

 

[Specialist]

The problem is that it's not just one final circuit that loses power, its several and its random.

Also the problem is coming from 2 separate fuseboards. We have done visual checks. We originally found one fuseboard had internal busbar damage which we have since replaced but the problem still persists.

It's so random that they could go days without anything happening.

Sorry just re read this, are you saying that after changing 1 board the problems still exist on that board ?

 

[Shorne]

Is it a 3 phase supply?

Yes it's a 3 phase supply Andy

 

[Shorne]

Sorry just re read this, are you saying that after changing 1 board the problems still exist on that board ?

Yes changed the kitchen DB but still problem exists

 

[Pete999]

You forgot food tel, but at that rate I'll meet you there

Can you get fined or something if you are caught DIS drunk in charge of a screwdriver?

 

[Specialist]

I'm thinking of putting voltage logger at main incomer i.e supply side of main switch to see if any issues at source. Asked UKPN to come out to set this up but that could be other side of Christmas

Sorry mate: Maybe I'm getting dense with age, but how would that help ? If it was a supply problem then all circuits on that board would drop out not one or two random circuits.

 

[Octopus]

Think there is more to this then the OP is letting on.....

Why would you change a CU for "just" busbar damage?

 

[Pete999]

 

[Shorne]

Think there is more to this then the OP is letting on.....

Why would you change a CU for "just" busbar damage?

DB is obsolete, no replacement parts available

 

[Octopus]

I think you need to charge the pub to ACCURATELY map ALL outlets, all CU's and then once you have that you may have an idea of which unit(s) are causing problems.

Most pubs are so lashed up, actually working out which circuit is which is like a mensa exam...

 

[Specialist]

@Shorne: Are both affected DB's 3 phase ?. Does the problem affect all phases ?.

One of the major causes we've had with random circuit drop outs in older pubs, is bad junction boxes in floor voids.
Seemed to be a matter of pride with some sparks, seeing how many JB's they could cram in.
Another thing we found a lot of, was crushed wiring where it had been laid in shallow beam notches under floor boards. But that usually causes random MCB / RCD drop out.
Obviously this will show up more as people walk on the floors above.

 

[Andy-1960]

I was thinking you may have a bad connection on one or more phases at the origin of supply to the building.. around the cut-out / meter.

It is also not unknown for the DNO to loose a phase, may be worth setting up a logger on the incoming supply.

 

[Specialist]

Hi Andy: OP says its only one or two random circuits dropping from a board, not a whole DB or even a particular phase.

 

[LankyWill]

Think there is more to this then the OP is letting on.....

Why would you change a CU for "just" busbar damage?

Such a pessimist Murdoch, although it is a bit suspicious.

OP why don't you start logging when these faults occur and start building a picture of circumstances surrounding the fault. Wouldn't harm tracing the offending circuits and doing some basic testing. Does any switchgear operate?(mcb,rcd etc)

 

[Octopus]

Such a pessimist Murdoch, although it is a bit suspicious.

Not a pessimist... more a realist!

Time and time again, people open threads with half, or less of the facts and information and don't come back with facts.......

We can only really help if we are presented with facts and answers....

 

[onions1066]

The story actually goes........... the landlord at my local asked me to swap the board in the kitchen ever since I did this there has been a problem with circuits dropping out. Can anyone help????

 

[onions1066]

Well seeing as you asked........I would put a logger at the incoming supply for a start as the previous posts said. It must be a loose connection somewhere

 

[Specialist]

The story actually goes........... the landlord at my local asked me to swap the board in the kitchen ever since I did this there has been a problem with circuits dropping out. Can anyone help????

Yep: Call an Electrician
Sorry, couldn't resist .

 

[davesparks]

Get them to write down exactly when this happens and where it has been noticed.

I expect it is happening to the same circuits every time, but the people who notice it are in different places when it happens so it appears to be affecting random areas.

 

[ruston]

Yes I would go with that too. Have you actually witnessed the fault .
How many staff have contributed to the story? It gets to be Chinese wispers.

 

[Shorne]

Yes I've witnessed the fault myself. In my experience it tends to only happen in the afternoon/ evening. Originally they were only noticing it on the first floor, which is the Kitchen and Office. This was obvious as each time it happens they have to reboot the computers, music, CCTV, Gas Interlock, Extract and Supply Fans. This is was all fed from one DB in the Kitchen. So the main incoming supply the Kitchen DB was tested, connections all check and was all ok. After looking further into the DB there was signs of Arcing on the Bus Bars behind the Breaker for a Three Phase Hoist Motor. We then replaced this DB. We originally didn't think that this was a supply issue to the building as Manager and Staff reported this as only affecting these circuits on the first floor. After nearly a couple of weeks with no issues, the pub have now reported that it has returned but now affecting circuits on the ground floor as well as the new DB in the Kitchen and apparently it wasn't before. These circuits for the ground floor are all fed from a separate DB in the basement. So even though UKPN have said there is no issues, our next step is setting up our own Monitor at the supply.

 

[Shorne]

The story actually goes........... the landlord at my local asked me to swap the board in the kitchen ever since I did this there has been a problem with circuits dropping out. Can anyone help????

No we are better than that, to rip of the customer

 

[Andy-1960]

Keep us posted of your findings

 

[onions1066]

No we are better than that, to rip of the customer

I was just messing chill.

 

[snowhead]

Don't forget that loss of supply can also be loss of Neutral.

 

[Andy-1960]

Don't forget that loss of supply can also be loss of Neutral.

I agree, but loss of neutral on three phase system would result in a much higher voltage across all single phase connected equipment, this would result in failure of some of these items and I do not think this is the case.

 

[Shorne]

Yes there is no failure in any of the equipment, everything comes back on after 2 seconds or it either requires resetting.

 

[dmxtothemax]

Careful analizes of the distribution system will reveal the fault
what part is common to all the affected systems ?
assuming it's just one fault
But it could also be several faults
but again they must have common points ?