2 out of 3 phases installed the wrong way round!

[johni0]

Hello. I hope someone can help. I've just discovered that on a new build house built just over a year ago there is a problem with the wiring from the incoming mains fuses to the consumer unit. Phase 1 was wired correctly. But the cable from Phase 2 on the main fuse is connected to Phase 3 on the consumer unit. Similarly the cable from Phase 3 on the main fuse is connected to Phase 2 on the consumer unit. This has caused some problems with smart apps misreporting energy usage, and the MVHR system has reported high voltage errors. Could the mistake have caused any damage to single phase or 3 phase equipment? There is a 3 phase solar inverter and a 3 phase electric car charger. Everything else at the property is single phase equipment.

 

[snowhead]

No it won't have damaged anything, it's fairly common in Commercial sites for phases to be wrong.
It's not a problem as the person making any connections, in any 3 phase installation, should be checking that the phase rotation is correct on the equipment that they are connecting.

 

[UNG]

Hello. I hope someone can help. I've just discovered that on a new build house built just over a year ago there is a problem with the wiring from the incoming mains fuses to the consumer unit. Phase 1 was wired correctly. But the cable from Phase 2 on the main fuse is connected to Phase 3 on the consumer unit. Similarly the cable from Phase 3 on the main fuse is connected to Phase 2 on the consumer unit. This has caused some problems with smart apps misreporting energy usage, and the MVHR system has reported high voltage errors. Could the mistake have caused any damage to single phase or 3 phase equipment? There is a 3 phase solar inverter and a 3 phase electric car charger. Everything else at the property is single phase equipment.

I'm not sure why you have decided that the problem is with the mains connection, as snowhead has said this is unlikely to cause any problems
I think you need to look at the solar and the EV charger more closely to identify your problem, I suspect you already have a high incoming voltage and the solar is taking this higher, while the charger is in use this should pull the voltage down slightly but when the charge is complete your high voltage errors may be caused by the charger shutting down or switching to a float charge mode causing voltage spikes
Are there any battery packs (powerwall etc) on site

 

[johni0]

I'm not sure why you have decided that the problem is with the mains connection, as snowhead has said this is unlikely to cause any problems
I think you need to look at the solar and the EV charger more closely to identify your problem, I suspect you already have a high incoming voltage and the solar is taking this higher, while the charger is in use this should pull the voltage down slightly but when the charge is complete your high voltage errors may be caused by the charger shutting down or switching to a float charge mode causing voltage spikes
Are there any battery packs (powerwall etc) on site

Hi. Thanks for your quick reply. There is a Tesla Powerwall, and it was the installers of this that found the problem. The Powerwall had been installed 9 months earlier, but the Tesla app showed incorrect information about how much power the house was using vs how much solar panels were generating. These problems were fixed as soon as the cables were swapped around yesterday. Not sure if they caused any of the other issues like voltage spikes. Maybe I'm putting 2 and 2 together and making 5! Time will tell if there are any more errors from the MVHR system...

 

[James]

It may cause you issues if the only thing that has been done is to change the incoming phases round.
if the phases have not been changed on all 3 phase motors they will be going the wrong way.
has anyone actually done a phase rotation check?

 

[johni0]

It may cause you issues if the only thing that has been done is to change the incoming phases round.
if the phases have not been changed on all 3 phase motors they will be going the wrong way.
has anyone actually done a phase rotation check?

Hi James. Not yet, but again the solar inverter and the car charger are working fine (as they were when the cables were the wrong way around). Not sure if I should be worried or if I'm making a mountain out of a molehill.

 

[Lucien Nunes]

If the phase rotation is wrong (i.e. two phases interchanged):

• Single-phase devices don't care.
• 3-phase resistive heating doesn't usually care either.
• Some 3-phase devices (typically electronics) won't work at all, won't work correctly and/or will flag an error.
• 3-phase induction motors will run backwards and possibly damage the driven machinery.

In a factory, reversing two phases of the supply and hence the rotation would cause havoc. It is sometimes wrong at the supply and carelessly put 'right' by uncrossing them elsewhere. Putting them right at the supply then makes it wrong everywhere else.

In a domestic scenario there might not be anything that will malfunction as a result, and most of the load is likely to be single-phase anyway. As above, the incorrect rotation is probably not responsible for the high voltage alarms.

 

[UNG]

Hi. Thanks for your quick reply. There is a Tesla Powerwall, and it was the installers of this that found the problem. The Powerwall had been installed 9 months earlier, but the Tesla app showed incorrect information about how much power the house was using vs how much solar panels were generating. These problems were fixed as soon as the cables were swapped around yesterday. Not sure if they caused any of the other issues like voltage spikes. Maybe I'm putting 2 and 2 together and making 5! Time will tell if there are any more errors from the MVHR system...

I'm a little bit suspicious that this was the issue, to swap the cables round would have needed isolation of the power which has more than likely reset a number of the components within the system and thereby cleared the fault maybe only temporarily.
Was the fault present immediately prior to swapping the cables or does this fault only occur under particular conditions.
I think with faults like this the only real way of identifing the problem is using a power quality analyser to moniter the electrical system for a number of days
Do you have powerwalls on all 3 phases

Hi James. Not yet, but again the solar inverter and the car charger are working fine (as they were when the cables were the wrong way around). Not sure if I should be worried or if I'm making a mountain out of a molehill.

I'm assuming you only have the EV charger and solar inverter that needs a 3 phase supply and all the other equipment is single phase

 

[johni0]

I'm a little bit suspicious that this was the issue, to swap the cables round would have needed isolation of the power which has more than likely reset a number of the components within the system and thereby cleared the fault maybe only temporarily.
Was the fault present immediately prior to swapping the cables or does this fault only occur under particular conditions.
I think with faults like this the only real way of identifing the problem is using a power quality analyser to moniter the electrical system for a number of days
Do you have powerwalls on all 3 phases

I'm assuming you only have the EV charger and solar inverter that needs a 3 phase supply and all the other equipment is single phase

The fault existed continuously for 9 months and disappeared as soon as the cables were swapped yesterday morning. The powerwall is on all 3 phases (but only provides backup on one phase). The installers are convinced the incorrect phase cabling was the fault. Time will tell if the problem is permanently gone, but so far so good.

You're correct that only the EV charger and solar inverter are 3 phase.

I'm more comfortable with the replies received that no real harm has been done. Thanks to all for your helpful responses.

 

[UNG]

The installers are convinced the incorrect phase cabling was the fault.

I'm not too convinced. Was this the first time they had come across this problem in how many installs sounds like a clutching at straws fix to me with no reason as to why the cable swap worked, or were the 3 phase cables connected wrongly at the powerwall and they didn't want to admit it
There are a lot of supposedly competent people out there that don't understand 3 phase

 

[timhoward]

When I saw the thread title I thought "Liverpool?" Nope, completely wrong train of thought!
(For historical reasons the Liverpool local distribution network has phases 2 and 3 swapped with the national grid every time they connect. I believe it's the only place in the UK like this. They tried to fix this in 1948 and gave up within 24 hours.)

Even though this isn't relevant at all, it might nonetheless reassure the OP that chances of any arising damage is almost zero for most things as an entire area has 2 phases reversed. Of course any 3 phase motors in this area are wired accordingly too!

 

[Algarve Sparky]

So the power wall was installed some 9 months earlier, the original installer of the power wall is at fault for not doing a full supply service check, and assuming the three phase rotation is suitably arranged for the power walls configuration was also their mistake, not the incoming supply phase rotation.

EV charging installations are not need taken seriously enough by many installers who have been on the one day course, with solar installs also subject to poor installs and poor design the chances for mistake to be made increase.

How did the power wall install get signed off if there was a configuration fault ? this should of flagged up when commissioned !