Wiring HF Flourescent Lights

[roger-bernhardt]

I am trying to wire a simple set up of two 6ft 70w high frequency twin tube fluorescent lights to be plugged in at a wall socket. These are the type with an electronic ballast/ no starter. I wired the mains cable to the terminal block of the 1st light and then a cable from the same terminal block to the second light. The second light worked fine, however the 1st light cuts out after 30-60 seconds. Afterwards, I tried the 1st light alone but it still goes out after 30-60seconds. I have tried changing the lamps.

Is it likely that I have a faulty unit? Could the wiring configuration I used have damaged the ballast? What is the correct way to wire two HF lights from the same power cable? Any help appreciated, Thanks.

 

[holmslaw]

..

 

[roger-bernhardt]

Thanks. Sorry I am not an electrician. I understand Live goes to Live, Neutral to Neutral, Earth to Earth, but could you explain the loop in more detail please?

 

[holmslaw]

..

 

[roger-bernhardt]

The lights do not have a separate block for a loop, only one terminal. I had the the L, N, E for the power cable wired to the terminal block in the 1st light and the L, N, E of a cable leading to the 2nd light twisted together with the L, N, E wires leading out on the opposite side of the terminal block on the 1st light. Was this correct? Thanks.

 

[Steve]

The lights do not have a separate block for a loop, only one terminal. I had the the L, N, E for the power cable wired to the terminal block in the 1st light and the L, N, E of a cable leading to the 2nd light twisted together with the L, N, E wires leading out on the opposite side of the terminal block on the 1st light. Was this correct? Thanks.

FOR THE 3RD AND FINAL TIME

yes. You wired them correctly. I dont know what other way you think you could have wired them.

 

[roger-bernhardt]

Well. It wasn't a faulty unit. I replaced it with a new unit. It worked fine for the first couple of tries, then the same fault occurred: lamps cut out after 30-60 seconds. Wired up as described above, so I've no idea why. Any ideas?

 

[crystal ball]

Another faulty unit? I worked on new factory where all the fittings had duff ballasts and had to be changed 200+

 

[roger-bernhardt]

I don't know, it seemed to work at first.

 

[crystal ball]

I spend a lot of time renewing HF fittings in a local school, quite often a tube will strike up for a short period and then go off when the ballast is faulty

 

[flameport]

I have tried changing the lamps

Are the tubes the correct type? i.e. 70W T8, rather than 75W T12 ?

 

[roger-bernhardt]

Yep. They are 70w T8.

 

[mikehammer69]

I spend a lot of time renewing HF fittings in a local school, quite often a tube will strike up for a short period and then go off when the ballast is faulty

do you know if a 35W HE fitting is comparable 'light output' to an older T8 58watt w/magnetic ballast

 

[bernardgreen]

Can you try the units one at a time to see if they work when only one is connected to the plug ?

It might be that the ballasts are taking power from the mains in very short but high current pulses from the mains and this is causing local voltage fluctuations ( on the cable from plug to lamps ). The voltage fluctuations caused by one ballast then disrupting the working of the other ballast and vice versa.

Sometimes this is "cured" by a capacitor across Live and Neutral, often mis-named as a power factor correction. If the lamps do work reliably one at a time then contact the supplier / manufacturer for their advice / recommendation as to how to prevernt this inter-action between ballasts.

On ordinary flourescents it is a power factor correction device, but on "rogue" high frequency ballasts it is a suppressor device.