Christmas lights or lack of.....!

Have you checked the 'earth leakage'' current (protective conductor current) from the driver (both static, and inrush)?

When  you say the circuit has failed - what exactly has happened - has the trip popped and refused to reset, has the driver stopped creating an output, has something actually gone bang  ?

Does it recover if taken indoors and warmed up for a couple of hours ?

My money on anything outside failing is usually water ingress or condensation due to hot/cold cycles. Have you done any kind of autopsy on the failed units?

Looking at the data for connect pro there are a number of variants, many of which seem to be double insulated 230V dasiy chain - so I presume its not those. Do you have data for the exact model as I cant see any mention of flash bulbs ?

Mike.

The product is MV002 - ten metre string with flash bulb.

As a product they are good VFM - especially on a business account rate !

It is double insulated 230 V - IP65 which is better than most on the ingress rating i reckon.   The sheath is HO3 which is just ok imho.

Further investigation points toward sheath failure on products in the quayside area where the wind was at its most strength. We use 316 stainless catenary to stop the chance of rust crystal chafing.

Further into the town area the product sheath is intact.

There were a number of whole town supply failures on Saturday - one for three hours. One phase on Sunday was causing a lot of problems with erratic voltages. At 1630 on time the MV002 products were off but all other products from same company worked and continue to do so.

I guess the question is how do the flash lamps work/fail ? 

Onward to today and 1200 metres of replacement ( non flash) have been ordered for installing this weekend.   At least it will be dry but cold !

OK well there is not a lot of paperwork is there!
I am assuming that as the LEDs will have a voltage drop of a couple of volts each, all in any short stringette are in series, so the 'flash' bulb has to break that, while the mains sails past to the next segment. but it is just a guess.
PDF

Might be worth connecting the lights to a small UPS fed from the RCBOs as this will help clean the power some what but also help to mitigate against power fluctuations especially in these current times of power cuts where the real damage can happen when the power is restored.

Is it inrush current related? I specify lighting circuits to be protected by type C MCBs / RCBOs.

The RCBOs are type C.

The one circuit of flash lamp product supplied by a different sub station in the town continue to work normally.

Which whilst slightly annoying I think proves that the supply variation destroyed the other 1200 metres.

Two days spent replacing the full quantity with NON Flash product !

Thanks to one and all for your thoughts.

Which whilst slightly annoying I think proves that the supply variation destroyed the other 1200 metres.

I suspect the flash ones would have some extra electronics, perhaps making them more sensitive to overvoltages. Were there any SPDs in circuit?

   - Andy.

There were no SPD devices - but most certainly will be for next year!

A number of devices in town - boiler PCB, Sky boxes etc were also fried on the same day..

A common cause when there are a lot of over voltage failures on the same substation is a wandering neutral -  if the neutral is high resistance or disconnected at the transformer end, then the single phase loads on the 3 phases pull what should be the centre of the triangle off, in the direction of the most heavily loaded phase the less heavily loaded phases then see an unnaturally high L-N voltage - up to almost 400V if you have maximum imbalance.

A surge arrestor, while from the name you might think it would deal with that, is aimed at much larger over-voltages, but of very short duration, perhaps kV and tens of microseconds  and  is not really designed to deal with modest over-voltages for a very long time - there is no-where for the power to be dissipated.

In countries where the mains is more unreliable than the UK, it is common to have something that disconnects the load if the supply is out of limits - say above 270V or less than 170V, and that reacts within a second or two, as well as the SPD.

A suspiciously cheap example https://www.aliexpress.com/item/32977199617.html

I have not seen one on a normal installation in the UK however I have specified something rather more up-market on kit intended to go overseas and be used with "power of opportunity" supplies.

Mike.