jimbob Posted October 17, 2007 Report Share Posted October 17, 2007 i got three arcadia t8 fluro ballasts (they say model ac36nz type C5) along with a filter i bought on trademe. they are rated for 36/38w tubes. anyways, i need to light a 2ft tank so thought that two 18w tubes in series would be the same as one 36w tube. so off to the hardware store i go and buy 2 $7 tubes. when i turn it on both of the tubes flash periodically (as they usually do when you turn on t8s) but don't stay lighted (i left it trying for about 30s before i turned it off. should this have worked? if not, can i make it work? if not, is it safe to just run 1 18w tube off this ballast? i would really prefer one tube anyway... Quote Link to comment Share on other sites More sharing options...
jayci Posted October 17, 2007 Report Share Posted October 17, 2007 one tube would be fine. Quote Link to comment Share on other sites More sharing options...
Ira Posted October 17, 2007 Report Share Posted October 17, 2007 Running two tubes in series doesn't always work. The problem is...Well...You're doing it wrong. With magnetic ballasts when you turn on the power the starter puts electricity through the at each end on each of the tube to heat them up. This ionizes the gas inside the tube enough for it to become electrically conductive. Once both are hot the starter flips over and tries to run the current from one end of the tube to the other which makes it light up. If the gas inside isn't conductive enough you just a blink, the light goes out and you have to start over. That's why you get the lights usually flickering a couple times before they stay on. When you run two in a series if either one doesn't actually light it breaks the circuit so neither will light and then maybe the next time around the other won't light... I have though gotten it work several times reasonably reliably, but I think you might need an oversized ballast to have much chance. There are a lot of fixtures that do have two lights run off a single ballast though, I think they use a special type of starter. Quote Link to comment Share on other sites More sharing options...
jimbob Posted October 17, 2007 Author Report Share Posted October 17, 2007 thanks guys. i thought it would work because when i opened up the unit (the person i got it from had cut all the wires so i needed to solder them together again) there were 2 circuits. one with a single tube, and another with two tubes in series. perhaps i could run two 45cm t8s? 13/14w it worked fine with one tube. i just wanted to know that it wasnt going to overheat or anything like that. ill just run it with 1 tube for a while and monitor it. thanks for the help Quote Link to comment Share on other sites More sharing options...
Ira Posted October 17, 2007 Report Share Posted October 17, 2007 No, it's not going to overheat. With fewer tubes it will actually be running cooler because it will be drawing less current. Quote Link to comment Share on other sites More sharing options...
Warren Posted October 17, 2007 Report Share Posted October 17, 2007 You can get two tubes in series going on the ballast you have. You need to by two new starters. There's a special type of starter for series connected tubes that allows them to start either at the same time or at different times so they don't just sit there flashing at you. Can't remember the type - S20 maybe. The electrical store you got the tubes from should be able to tell you which starter to use and the circuit for wiring them is somewhere on the internet (if they don't know that as well)... Quote Link to comment Share on other sites More sharing options...
alanmin4304 Posted October 17, 2007 Report Share Posted October 17, 2007 When I have used two tubes in series I used a starter on each tube and they worked OK. Quote Link to comment Share on other sites More sharing options...
jimbob Posted October 17, 2007 Author Report Share Posted October 17, 2007 thanks guys, i will try and find out what starters i need and look for a circuit online. Quote Link to comment Share on other sites More sharing options...
jimbob Posted October 17, 2007 Author Report Share Posted October 17, 2007 for anyone interested this site contains a circuit: http://members.misty.com/don/f-lamp.html#wd9 however i think i should leave this fiddling until after my uni exams which start in a week Quote Link to comment Share on other sites More sharing options...
richms Posted October 18, 2007 Report Share Posted October 18, 2007 The ballast regulates the current, so if you put a 20 watt tube on a 38 watt ballast, you will be overdriving it. Wont last long like that, but will be nice and bright while it works, till it cracks from overheating Quote Link to comment Share on other sites More sharing options...
jimbob Posted October 18, 2007 Author Report Share Posted October 18, 2007 that was what i was concerned about re running one bulb. didnt know what the ballast did, and i was worried about something like that... think i will just hold off on everything til i have more time to investigate... the tank doesnt have anything in it at the mo, was just wanting to be prepared... Quote Link to comment Share on other sites More sharing options...
richms Posted October 18, 2007 Report Share Posted October 18, 2007 Bare magnetic ballasts are about $8 last time I bought one from an electrical wholesaler, so if you need a certain wattage, then go that route, but by the time you get endcaps and starter sockets and the .75mm solid core wire you need to wire it up, the pre made one on petplanet that does t5's looks like a better and better deal. Quote Link to comment Share on other sites More sharing options...
jimbob Posted October 18, 2007 Author Report Share Posted October 18, 2007 ha yeah, i got a twin t5 unit from there for my 3ft brackish tank. if you go into the shop michael is a great source of info too just that i have these three units that i got along with a filter i bought, so thought if i could get them to suffice it saves me spending money on a 2ft light. i am a student after all... in the holidays i will look at wiring one up with a second starter... or instead i could save the hastle and just work a few more hours to pay for a unit... hmmm... thanks for the info everyone Quote Link to comment Share on other sites More sharing options...
AMAZONIAN Posted October 20, 2007 Report Share Posted October 20, 2007 Hi All As Warren says ypu can connect the two 18 watt tubes in series and use "S2" Starters. The starter goes across the tube (from one pin on one end to the same side pin on the other end) The left over pin on one end goes to the other tube and the other to the "L" contact on the ballast. Good luck. Electrical Regn. I2887 Quote Link to comment Share on other sites More sharing options...
jimbob Posted November 2, 2007 Author Report Share Posted November 2, 2007 fyi the 2 s2 starters worked a treat. i now have 2 2fts running on a tank i temorarily set up to hold some fish until my saltwater tank is ready. only prob is i didnt know what tubes to buy from the hardware store, so 1 of the ones i bought is a horrible yellow colour. ha, oh well, its only temporary.... Quote Link to comment Share on other sites More sharing options...
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