Bulbs constantly blowing

[Northernladuk]

We have a small club with a number of wall lights and ceiling lights. The wallas are plasterboard and ceiling is suspended. For some reason we have a few fittings that will blow a bulb in less than a day, other will alst a few days and the bulb blows.

Can anyone shed any light on why the bulbs are blowing so often? They don't flicker and the fuses arn't going. They stay on for about 16 huors a day but some don't even last that long.

Many thanks

 

[Big_Spark]

Couple of things to consider.

1: Loose connections...this will shorten the life of lamps due to spiking on the circuit.

2: Cheap and nasty lamps.

3: Replace lamps for compact fluorescent lamps (Energy saving bulbs to most people)

I would suggest you get someone who KNOWS what they are doing to check out the lighting circuit. The loose connection could be a dodgy switch or simply old wiring.

 

[BR]

Another point to consider would be high voltage, however it would have to be significantly above the standard (222VAC - 244VAC) to be the cause of your problems. Are you running any other electrical equipment in the building?

 

[Northernladuk]

Interesting comment about the other electrical stuff in the building. It is a converted old building so each floor is rented off and has it's own electrical supply. Wonder if it is anything do with that.

I will take all the lamps back off and check all the connections I think. It across the whole floor and the outside lights so they are on diff circuits. Some worse than others granted. Different bulbs going as well so the high voltage sounds interesting.

I presume this is something the electric company will have to check?

 

[Big_Spark]

It is unlikely to be constant high voltage, you would see damage to other equipment in the area.

However, it could be spiking due to local influences or a faulty power Tx on the distribution side.

It would be a good idea to talk to the other residents of the building and finding out if they are experiencing similar problems, if they are then you should call your landlord and the supply company and get the supply checked.

If it is only onl;y occuring to your unit, call your landlord, they have a legal requirement to ensure your installation is safe, ask to see the last Periodic Inspection and Test certificate, it should be no more than 5 years old, if it is then he MUST arrange for a new one to be undertaken.

I would urge you not to spend your own money sorting out a problem that your landlord has a legal requirement to do.

 

[BR]

High Voltage is 99% of the time down to the supply company. Ask them to test it for you but ensure that they install a meter that will record the readings over a week or two, not just a once off measurement.

If the building is suffering from high voltage, then the entire building will be affected, not just the lighting circuit. This is why I am wondering if other apparatus is in use, Items like t.v.'s , P.C's etc are more sensitive to HV or high voltage transients than lamps. I was thinking that this was perhaps a hall or something where only lighting was in use.

It is not unusual to come across HV in domestic installations. I have often measured upwards of 300V P/N in houses.

If other appliances are functioning normally (especially the ones listed above) then the problem is much more likely to be loose connections as FWL pointed out

 

[BR]

Your post 'got in' before mine FWL! sorry if I've repeated any of your comments.

When I say the entire building, I am referring to each ‘floor’, which has its own electrical supply in you case.

 

[Big_Spark]

It is not unusual to come across HV in domestic installations. I have often measured upwards of 300V P/N in houses.

If other appliances are functioning normally (especially the ones listed above) then the problem is much more likely to be loose connections as FWL pointed out

Jesus you must have some dodgy generating companies in Ulster BR, the highest I think I have ever recorded on single phase circuit in the UK was no more than 260V, and this was traced to a 11KV transformer in the basement of the building that did not have symetrical windings.

The average in the UK will come in at about 242V, but this will vary between 238 and 244V as a rule.

 

[BR]

Jesus you must have some dodgy generating companies in Ulster BR, the highest I think I have ever recorded on single phase circuit in the UK was no more than 260V, and this was traced to a 11KV transformer in the basement of the building that did not have symetrical windings.

The average in the UK will come in at about 242V, but this will vary between 238 and 244V as a rule.

As your new here, I'll give you the benefit of the doubt, I am the area engineer with the only electricity company here, the ESB

As you can probably imagine, It is extremely difficult to accurately calculate the exact voltage that is going to be produced at the end of a transformer loop, especially when the area is large and large fluctuations occur in load.

The 300VAC was the exception rather than the rule and this was many years ago in new houses. New controls, AFT correction etc. has widely improved this problem.

Has the U.K’s actual voltage not now been corrected to 230VAC. We had to do so with our’s.

 

[Big_Spark]

230V is the voltage of design. I use it when doing the calculations, however in reality it is still 240V.

Normally if you measure it you get these readings.

Single Phase: 238.6 V
Three Phase: 413.2V between phases.

I suppose as generators update alternator sets and newer plants come online over the next 20 to 30 years then it will drop to 230V and 400V respectively.

 

[altec]

Br & FWL_engineer, ye are probably the most knowledgeable people here and the guys I would love to spend a day with! However there are a few terms being used which i don’t understand and perhaps if either of you get a chance you might answer some of them

(a) faulty power Tx

(b) symetrical windings

(c) alternator sets

(d) SWA

(e) AFT Correction

Also I note FWL speaks about a disconnection time of 5 secs should a fault occur. Does this refer to a short circuit fault (5secs seems like a very long time) or an overload or what exactly?

Thanks BR & FWL for your time

 

[Big_Spark]

(a) faulty power Tx

(b) symetrical windings

(c) alternator sets

(d) SWA

(e) AFT Correction

Also I note FWL speaks about a disconnection time of 5 secs should a fault occur. Does this refer to a short circuit fault (5secs seems like a very long time) or an overload or what exactly?

Faulty Power Tx refers to power transformer. What I am referring to is the 11KV/415V three phase transformers located in substaions on street corners, in building and on poles. They varyn in size depending on the load to be put through them.

Symetrical windings was simply a term I used I jnew BR would understand what it meant. The windings of any 3 phase power transformer must be symetrical, ie, all three input and all three output windings must have the same number of turns forming the respective windings and the ratio's must be the same to ensure that the output of all three phases is identical.


Alternator sets = the very large Alternators used for Power generation in Power Stations

SWA = Steel Wire Armoured, this is a type of cable used in the electrical industry.

AFT correction??? Not sure where you got that one from so without any context I cannot see what you mean. The nearest I can think of at this time of night is Power Factor Correction (PFC), and if that is it, I will not enter such a discussion here at 11pm!!

The disconnection time does indeed refer to the MAXIMUM permissable time taken for a protective device to disconnect the supply to a given circuit should a fault occur.

5 seconds may seem a long time, but in reality it should never be anything like that long if the circuits have been designed correctly and you have MCB's or RCBO's in place.

A lot of the disconnection times date from the days of the old BS3036 rewirable fuses.

In commercial, industrial, temporary installations and structures outside the equipotential zone (outside buildings) the maximum disconnection time should never exceed 0.4 seconds.

 

[securespark]

I use 240 in calculations like FWL says it might be 230 on paper, but in the real world...

My lowest and highest V readings are 229 and 251.

 

[BR]

AFT correction is a new technology which will be introduced in Ireland in the "coming years" . It involves the taps on a transformer, along with many other components, being computer controlled. One of the main aims of this system is to prevent excessive voltage fluctuations with load. In theory the entire thing sounds great, but as courses that I'm doing at the moment show, I has it's problems.

This is of course a issue concerning power distribution at supply level and not a diy issue as such.