Advice required

[Michael001]

Hello all, hope somebody can shed some light on an ongoing problem I’m experiencing on an old property.

I have installed and replaced 3 Heatmiser neo stats and a pump. Basically the internal relays have blown on the neo stats, I didn’t get a report back on the pump but this has also packed up within less than a year -not had a single problem with these pumps in other installations. I have checked all the connections a number of times, spoke to the tech guys at heatmiser and the pump suppliers and they have both advised there shouldn’t be a problem as the neo stat relay is capable of switching larger pumps. I then wired the pump and neo stat via a heatmiser wiring station that has a larger relay and to date have not had any further problems. I have been installing these heating controls and pumps for years and I do it exactly the same way and have never experienced a problem.

Next - same property, I installed a Extraflame wood pellet burner, it is now on its second winter. A few months ago I had to change the ignitor, I understand that this is a wear and tear part but I was surprised that it needed changing so soon, I’ve been installing extraflame pellet boilers for around 7 years and this is the first ignitor I have had to change. The burner is now experiencing other electrical problems, I recently linked the burner up to the internet so the tech people could carry out diagnostics, they couldn’t find any problems. Since then the burner has failed again and may possibly need a new motherboard.

The property is divided into 3 properties, the property that is experiencing all the problems has an old consumer unit, the lady that lives there advised that part of the property has electric under floor heating and she often has to reset the times on the programmer as they are lost as if there had been a power cut however she can’t recall a powercut.

My question is: Is it possible that there could be a problem within electrical system causing the problems. It just seems so bizarre that I have only experienced these problems at this property. As I have already written, I have installed many of the systems the same before and after this installation which are not experiencing any of these problems.

Many thanks for reading, hope somebody can help.

 

[Lucien Nunes]

It's unlikely but possible. Bad power quality often gets blamed when no other cause can be found to link together unexpected failures, so one must tread with caution and look for specific evidence of a specific type of fault. The loss of programming on the UFH controller is interesting corroborative evidence but one must not read too much into it at this stage, not least because even if it is highlighting PQ issue it does not tell us of what kind, in the way that a logger would.

The only failure mode that is truly likely to cause widespread component damage is a broken or high-resistance neutral in a 3-phase cable serving single-phase loads, such that the phase with the lowest demand sees an overvoltage. There are often very clear signs - the lights flicker and dip in response to any appliance being turned on, using the cooker stops the dishwasher working etc, and sometimes things randomly go pop. If any of these symptoms is present and/or the property uses one phase out of a 3-phase service, I would check this as a possibility. A broken neutral in the single-phase section, or even a broken CNE (which can be a shock risk) will not cause overvoltage damage.

Voltage spikes on the mains from elsewhere can cause damage but tend to be a rare-but-severe kind of phenomenon rather than an ongoing issue, unless they are caused by a piece of heavy plant disrupting the line. Again there would usually be other clues visible to the householder throughout the installation if the transients were so severe as to blow up the equipment.

Some equipment does not like having its supply frequently interrupted as would occur with a bad connection, which could be localised to a single circuit and so not cause any other symptoms. But if it is bad enough to keep blacking out a circuit so much that the equipment blows up, it is likely that there would be periods of time where it would be clearly dead, and then come back on, and the customer would report that fact. Also, a connection can only arc for so long before it goes open altogether or starts to burn up and thereby reveal itself.

 

[Michael001]

It's unlikely but possible. Bad power quality often gets blamed when no other cause can be found to link together unexpected failures, so one must tread with caution and look for specific evidence of a specific type of fault. The loss of programming on the UFH controller is interesting corroborative evidence but one must not read too much into it at this stage, not least because even if it is highlighting PQ issue it does not tell us of what kind, in the way that a logger would.

The only failure mode that is truly likely to cause widespread component damage is a broken or high-resistance neutral in a 3-phase cable serving single-phase loads, such that the phase with the lowest demand sees an overvoltage. There are often very clear signs - the lights flicker and dip in response to any appliance being turned on, using the cooker stops the dishwasher working etc, and sometimes things randomly go pop. If any of these symptoms is present and/or the property uses one phase out of a 3-phase service, I would check this as a possibility. A broken neutral in the single-phase section, or even a broken CNE (which can be a shock risk) will not cause overvoltage damage.

Voltage spikes on the mains from elsewhere can cause damage but tend to be a rare-but-severe kind of phenomenon rather than an ongoing issue, unless they are caused by a piece of heavy plant disrupting the line. Again there would usually be other clues visible to the householder throughout the installation if the transients were so severe as to blow up the equipment.

Some equipment does not like having its supply frequently interrupted as would occur with a bad connection, which could be localised to a single circuit and so not cause any other symptoms. But if it is bad enough to keep blacking out a circuit so much that the equipment blows up, it is likely that there would be periods of time where it would be clearly dead, and then come back on, and the customer would report that fact. Also, a connection can only arc for so long before it goes open altogether or starts to burn up and thereby reveal itself.

Many thanks for your detailed reply, I do believe the electricity supply is 3 phase serving single phase loads. Is it an easy task to find if there is a problem with neutral? Is this a task that can be done by general electrician or is there specialist fault finding equipment required? Sorry If I may come across a little dim.... It’s not my profession.
cheers M

 

[UNG]

Any electrician "should" be able locate the problem although I know many that don't do and claim not to understand three phase

 

[radiohead]

I had a similar issue in a rural property with an unexpectedly high rate of appliance failure and identified a voltage which reached 270v at various times of the day. Without a logger I resorted to leaving a megger earth loop plugged in and asking the owner to record the voltage every hour.
The DNO took some persuading that there was a problem as on two separate visits by them the voltage was acceptable, but a couple of days later the owner called me to say they admitted an issue and had transferred her to a genny until a replacement transformer could be sourced.