lamps blowing on ring cct and lighting cct...

[crunchynut]

Hello folks,

Been to look at a house today where lamps are blowing 2-3 times per week. Though she may be exaggerating a lil!

Lamps in question are both on lighting ccts and on 3A plug tops. Have checked some of the switches and lamp holder terminals of affected fittings and are seemingly ok.

Thought vibration may be an issue but some fittings unlikely to suffer from that. Cust had a mix of cheap and Philips (branded) lamps; both blew at same rate....ish... Told her that GU10s are often carp and can blow a lot. Though most of the fittings affected have good old incandescents

A couple of fittings may have issues with heat dispersion due to 'tight' diffusers. But the plug top lamps have ample room.

Cust also said her 13 month old TV went kaput recently. Apparently the power-pack was buglered and the spark/technician said he had never seen anything like it.
Me not being au fait with electronics so much, am wandering if the power-pack issue could be indicative of overvoltage on the supply, and this maybe the cause of the problem.

Incoming voltage a little high at 249V (measured 5 times over a 40 min period). Going to pop back tomorrow to see if any change in that.

Out of curiosity, have many of you measured domestic supplies at much above the 253V limit. And how do DNO's turn it down; is it at the sub or is it done remotely..

Any thoughts/help/comments appreciated.

Ta

 

[crunchynut]

Sorry forgot to add that if V is ok still. Then am planning to ensure terminals on sockets are sufficiently tight.

Any other pointers welcomed. Thanks again.

 

[pjcomp]

Is she close to the substation (bottom of the garden...)? Might be getting high spikes - you obviously didn't get any lamp-blowing during your monitoring period. Do the lamps blow during a particular period of the day? Do they blow when she switches them on or while in service? Do they take out the MCB when they blow (not relevant if she's still on rewirable fuses)?

Can't think of any other clues to follow at the moment...

PJ

 

[electronicsuk]

Check for loose supply tails?

 

[flameport]

If there is a supply problem, the only way to prove this is to hire a power quality analyser and leave this connected to the customers supply for a week or so.

However a more likely cause is that the customer has a large number of lamps, and although has to replace lamps often, it isn't the same ones which are being replaced each time.
Poor quality lamps which last for 1000 hours sounds like a lot, but once you have 40 of them in a house, thats a failure on average every 25 hours of use.

This is a problem which is common where people have ceiling downlighters in every room, and they replace lamps here and there, rather than replacing the entire lot after a certain amount of time.

 

[sparkwright]

Check for loose supply tails?

Or loose wires/breakers at cu.

Or loose wires anywhere.

 

[crunchynut]

Thank you all.

PJ, nearest sub I know is approx 100m away, may be one closer though. Didn’t ask time of day though I thought that afterwards I should have done. Blows on switching and during use. From what I could gather they usually knock out the MCB. She was a bit preoccupied with sick toddler so didn’t quiz her to much. Thanks for thoughts gives me some other clues to go off.

Gonna check for loose term’s/tails tomorrow in greater depth as bit pushed for time today – Thanks Elec and SW.

Flame, did think of this if nothing else became apparent. Do ISS rent them (sorry can just google that!). Very good point re the statistics of replacement lamps! Will highlight this fact to her tomorrow. There are a lot of lamps in some of the fittings.

Thanks all, give’s me something to bite on tomorrow. I shall thank thee all!

 

[SUNRAY]

I had this problem at a house I purchased 30 years ago, it was the first of about 70 on the supply from the sub. 270V was quite common and a pen recorder showed spikes of 300v. Eventually Seeboard fed the street from both ends and retapped the sub.

Had a similar situation more recently (255 - 260V), Seeboard found nothing wrong but the problem went away after their visit to the sub.

 

[crunchynut]

Thanks Sun,

Will check for more local sub around tomorrow. A lot of lamps are still designed for the old 220V common throughout mainland Europe before harmonisation I believe, so 250+V spikes will not help em!

Just looked on wikipedia, apparently 'standard' mains voltage can often fluctuate between 160-280V in Afghanistan..Blimey.

RE 255-260V: Seeboard sparx prob just unwound a bit mate........!

Cheers.

 

[SUNRAY]

RE 255-260V: Seeboard sparx prob just unwound a bit mate........!

Cheers.

I'm sure they simply adjusted the tap at the sub, the regular readings I took prior to their visit were consistanty 10 - 15V higher than those I took after the visit

 

[crunchynut]

Thank you all for inputs. Have been round to house now 4 times; V ranged from 247- 252. Around 70 lamps in use in house (3 bed terrace, believe it or not!), 'chandelier' in lounge has 11 ses lamps in it....ridiculous..

Told client it most likely due to a combination of factors: too many lamps reaching old age at same time,mentioned how commercial premises often re-lamp to avoid this (Flameport); a nominally high voltage not helping over time & close-fitting diffusers compounding issues. She was somewhat put off by cost of an analyser to test mains over a week. Plan of action is to 'map' exactly where new lamps are fitted, and leave it for a couple of months to see what happens.

Thanks again.

 

[JohnD]

CFLs are very tolerant as well as long-lived and money-saving.

On a good day you can get them for 10p in Tescos and Wickes in my town. Most are the standard sticks but I stocked up on SES candles and small spots when they had them on offer. Where they show I use pearl globes but the 150mm ones are not cheap.

70 lamps at 1,000 hours should mean one filament lamp fails every 14 hours.

I find small kitchen spots have a particularly short life, and are very prone to tripping the MCB. You can get small CFL spots but they are bigger and more expensive.

Get a marker pen to write installation date on the base of lamps on the day they are fitted.

 

[ban-all-sheds]

70 lamps at 1,000 hours should mean one filament lamp fails every 14 hours.

Unless the industry has changed the way they describe lamp life, 70 lamps at 1000 hours means that by 1000 hours 35 of them will have failed.

 

[JohnD]

so if they're described as 1000hr lamps, what is the average lamp life?

 

[flameport]

Have been round to house now 4 times; V ranged from 247- 252.

If the voltage is consistently that high, and the customer uses lots of incandescent lamps, then another option is to fit a transformer to reduce the voltage on the lighting circuits by 20v or so.