2D 28 Watt light fitting + emergency light fitting

[Si-Woz-Ere]

Hi all,

Got a problem with some 2D 28 Watt fittings, with some having emergency battery backup. I was asked to go to a block of flats where one of the residents had noticed that the power consumption for the communal lighting was using around 20-27 KW of power everyday depending when the lights came on as they are on a photocell sensor so they only come on when it's dark which is at different times depending on the time of year.
There are 34 28 Watt 2D fittings of which I think 12 of them are battery backup ones. He had a domestic energy meter which I put on the lighting circuit and sure enough the light was drawing approx. 2.5Kw an hour where it should only be drawing 952 or probably nearer 1Kw+ allowing for a slight discrepancy.
There were a few lights out and a few lights flickering and some battery backups not working either. I fixed all this and still get the same reading. I have tried putting lower wattage lamps in but the energy consumption goes up not down. I have taken all the lamps out and tested the energy consumtion of one 28 Watt lamp to be 66 Watts and and one 16 Watt lamp to be 95 Watts.

Any ideas how I can get the consumption down as I am a bit stumped as to why its doing this?
Many thanks

 

[polo1]

Hi, my first instinct would be to check what else may be being fed from the same circuit!

Regards.

 

[snowhead]

Block of flats?

Me thinks someone is getting some free Leccy, but they won't come rushing out and say the power has gone off.

What about 2 x 500w halogens on the roof or lights in the tankroom or in the lift motor room?

How many flats in the block?

Go back at night and turn off all the power except the communal area and see who's still got lights on

 

[onions1066]

Are they self contained or central battery system?

 

[Si-Woz-Ere]

They are self contained fittings. I can find nothing else fed from this circuit. There are about 30 flats I think. There is no lift and the basement and outside lights are off seperate circuits. I can't see how anyone would be able to take power from them due to where they are situated buut like I say I took all the lamps out and measured the consumption and then then I put one lamp in and mesured one 28 Watt lamp at 66 Watts and a 16 Watt lamp at 95 Watts. Should the power consumption increase with a lower wattage lamp?

 

[preston]

try measuring by other means EG.clamp meter and then calculate or may be the watt meter being used is not set right or not working properly...........

 

[snowhead]

Where was the resident measuring the Wattage, in the board on the outgoing cable?
Are you at the same point?

As above suspect the meter first, check it on a kettle.

 

[preston]

all the units cant be wrong and electronic calculating devices are not allways right ,,i would allways compare if confused....

 

[ayjay]

what size is the circuit breaker or breakers? clamp the outgoing circuit to see how much current is flowing

 

[Thomas123]

could be the insulation resistance is down? if you have a resistance of roughly 60 ohms between line and neutral it will allow 4-5 amps to flow.. which may be that extra kw thats being used..

unlikely but possible


its most likely one of the fittings, good luck

 

[SKY]

I have seen someone spur out of the back of a single socket in a communal area into a flat bedroom recently.
This fed an extention which ran most of the flat!

I do see a lot of naughty bits as one of the firms I do call outs for out of hours are the principial contractor for our police force.

 

[mackers]

i would say theres a flat connected! came across same thing couple yrs back old caretakers flat wired off communals!

or maybe theres a flat full of funny looking plants with lots of son lamps connected?

 

[ayjay]

thats what i was thinking mackers but surely the trip would well-- trip?

 

[i=p/u]

Cheap lights ,as you say you bought 28w but it pulling more so as you say turn all off and measure = 0 then add new 1 from wholesaler and = Or volt drop

 

[technospark]

Have you considered the power factor. If these fittings are wire wound rather than electronic, and do not have a pfc. capacitor then the consumption can rocket.

 

[accordfire]

Each fitting should be drawing around 0.15A running - allow maybe another 5mA for charging circuits on those with emergency lighting conversion.

20mA *34 fittings - 680mA or 6.8A allowing for variances, you shouldn't see more than 8A on the circuit at all.

Ohms law tells us that 8A at 230V nominal should be around 1.84kW. That's 1.8kW running - for an hour would be 1.8kW/h. You'd get to your figure fairly easy if the lighting is running say 14 hours a day - not unlikely in winter - and not unlikely if the dawn to dusk sensor isn't in a great daylight position. The official length of "daylight" is currently around 9 hours. That increases to around 16 mid July, and drops to a low of around 8 mid winter - end of Dec.

My guess, unlikely much is wrong at all, and figures as expected.....