bulbs burn then smoke and go out.

Discussion in 'Landscape Lighting' started by n2h20, Jun 8, 2005.

1. n2h20LawnSite Senior Memberfrom Pasadena, CaMessages: 503

i dont know if it make a difference but now all (6-8) fixtures have no bulbs in them and she says the all blow out no matter which one you put the bulb in. I will try and stop by tomorrow to get the exact wattage of the transformer and how many fixtures..

2. fixer67LawnSite Silver Memberfrom Tryon NCMessages: 2,098

A lot of people here keep talking about "wattage" being the problem. It is not. The problem here is voltage. I can take a 12 volt 7 watt bulb and hook it up to a car battery which can put out over 12,000 watts of power for a short time(12 Volt 1000 AMP battery) and by the way I have an 800 AMP battery in my car right now. Any way the 7 watt bulb will run just fine with no problem. It is the VOLTS that is causing this problem. Either you have 6 volt bulbs on a 12 volt transformer or 12 volts bulbs on a 24 volt transformer or the transformer is messed up and needs to be replaced. I once seen a mess like this where there was no transformer. The man though he could just plug the lights straight into the 120 VAC wall outlet.

3. NickNLawnSite Bronze Memberfrom AlabamaMessages: 1,009

Well,with a 100 watt transformer and let's say 15V output,you would have 6.66 amps max.
As for all systems having a short,no they don't.Unless your talking about the filiment in the bulb as a short.The filitment though,is creating resistance,so it's not a short.It acts like a resistor.A short has very little resistance,approx. .1ohm.So,even with a 100 watt transformer,if their was a short(.1 ohms),yes you would still blow the bulbs because then you would be creating 1000 amps of current. (100 watts/.1ohm)
You would create even more current than the 500 watt transformer,because current is inversly proportional to power.(P=IxE)
As the power increases,the current and voltage will decrease,but as the power decreases,the current and voltage will increase.
This is why 110volts AC is more deadly than 220V AC.It carries more current.Current always finds the shortest path to ground.When someone is electricuted,they are the shortest path to ground.They are the conductor.

4. dvmcmrhp52LawnSite Platinum Memberfrom Pa.Messages: 4,205

[

O.K.,
If current is measured by amps as you've stated,How can a 100 watt transformer put out more current than a 500 watt transformer?
Or are we only speaking of more current out of a 100 watt transformer than a 500 watt when a short is present?

Let's see...........at 100 watts it takes more current to produce the same result compared to 500 watts?

When I said I think most systems have shorts I did not mean an absolute short......more like the spark plug wires on a vehicle when they are "leaking" and throwing "sparks"..........
Not an absolute short to my way of thinking but a short that reduces efficiency............Make any sense?

One last question................maybe........lol.
Why will a larger than necessary transformer reduce the life of the bulbs?......( a 500 watt transformer running only twenty 7 watt bulbs)

Maybe I'm just too feeble for all of this, but............lernin is good............

5. T EdwardsLawnSite Memberfrom Columbia, SCMessages: 230

n2h20

I would check the voltage across the output terminals of the transformer. Sometimes weird things happen in the secondary side. On the primary side if the windings are open you get zero output, and if they short it will trip the disconnect unit.

Sometimes you may find a transformer that has no business being in that circuit.

6. n2h20LawnSite Senior Memberfrom Pasadena, CaMessages: 503

thanks again i will get over there this weekend to take a look/...

7. NickNLawnSite Bronze Memberfrom AlabamaMessages: 1,009

Because current is inversly proportional to power.It's basic Ohm's law.
Let me see if this will work.
P
------
I * E

P,being power is over E(voltage) and I(current).In this formula,the current and voltage are proportional,but both are inversly proportional to power.
You can use this formula to find Power by multiplying I * E.You can also use it to find the current(I) if you know the Power and (E)Voltage by dividing the E(Voltage) into the Power(watts).
Or,if you know the power and the current(I),you can find the voltage by dividing the current(I) into the Power.Hopefully the formula above helps.

8. NickNLawnSite Bronze Memberfrom AlabamaMessages: 1,009

<i>Let's see...........at 100 watts it takes more current to produce the same result compared to 500 watts?</i>
In a way,yes,but it's more of a byproduct created by the power and voltage.
It's not necessarily needed,it just happens.Again,Ohms Law.

9. NickNLawnSite Bronze Memberfrom AlabamaMessages: 1,009

" Why will a larger than necessary transformer reduce the life of the bulbs?......( a 500 watt transformer running only twenty 7 watt bulbs)"
Too much power,just like a 500 watt amplifier will eventually blow a 10 watt speaker.The bulb is rated(or made) to withstand a certain amount of voltage,current,and power.If any of these is too high,it will reduce the life of the bulb,because the bulb wasn't designed to withstand the load.

10. NickNLawnSite Bronze Memberfrom AlabamaMessages: 1,009

I should have also stated,the Power itself being higher won't shorten the life a whole lot.