no worries, i just don't have the ability to explain the difference. basically you are just adding up the voltages per leg... 120+120=240. but in a 3 phase you have 3 120v legs. if you calc'd the way you went, the system would be 360v versus the 208v that it actually is
electrical help! 208v - 120/240
- Thread starter irobot sd
- Start date
no worries, i just don't have the ability to explain the difference. basically you are just adding up the voltages per leg... 120+120=240. but in a 3 phase you have 3 120v legs. if you calc'd the way you went, the system would be 360v versus the 208v that it actually is
depending on the insulation rating, which is listed on the cable jacket, that will help determine allowable ampacity. that could be betweenn 40-45 amps.
so here is the math on the amount of lights you can run given you said you are running 600's. I'll calculate at 120, 208,240:
600w/120v=5 amps
600w/208=2.88 amps
600w/240=2.5 amps
so you can see that you can run twice as many lights on a 240v circuit versus a 120.
with any circuit, you don't want to exceed 80% of the wire rating.
So first... can your ballasts run at 208v or not? yes, i know they will do 120/240, but this is important. if it doesn't run at that voltage, can you return them? can you get a ballast that runs at 208v? can you return the cap controllers?
i can explain alternatives, but i need to know what options are there. worst case you run everything at 120v and don't use the controllers.
electricity is serious stuff and unless you know what you are talking about, you can seriously lead someone in the wrong direction that can be both expensive and costly to life. the problem is that most people don't really get how it works, or just have enough information to be dangerous, or think they know more than they actually do.
an example of a quad tap ballast:
http://cgi.ebay.com/1-600-Watt-High-Pressure-Sodium-Ballast-Kit-Quad-Tap-/150501286911#vi-content
something like this allows you to use your crap controller.
http://cgi.ebay.com/1-600-Watt-High-Pressure-Sodium-Ballast-Kit-Quad-Tap-/150501286911#vi-content
something like this allows you to use your crap controller.
dgr
Member
irobot,
You sorta forgot to mention that minor detail that you'd be running 16 lights.
What brand are your ballasts? There are ballasts out there that are labeled as 120V/240V that can be converted to 208V. E.g. SG ballasts have a 208V tap in them. Someone with the knowledge pops the cover, disconnects the 240V tap from the feed and connects the 208V. Then labels the ballast that it is now 208V. DONE.
You sorta forgot to mention that minor detail that you'd be running 16 lights.
What brand are your ballasts? There are ballasts out there that are labeled as 120V/240V that can be converted to 208V. E.g. SG ballasts have a 208V tap in them. Someone with the knowledge pops the cover, disconnects the 240V tap from the feed and connects the 208V. Then labels the ballast that it is now 208V. DONE.
i know that is kinda crucial detail = ) . That is my next action I'm heading to the hydro store to open one ballast. They are the extra sun 600w hydrofarm. Hopefully they have a 208 tap and I can get them all switched. They look very similar to the SG ballasts you suggest. Thank you everyone who helped me out in here! Lots & lots of useful info in this thread.
Frequently Asked Questions
Q: Will my dual voltage 120/240v ballast operate on 208v?
A: Yes, all of our magnetic ballasts have a 208v lead coming out of the transformer located inside the ballast housing. You may have them specially ordered to operate 208v instead of 240v, or if you already have a Hydrofarm ballast, consult a certified electrician to rewire this for you. It is a very simple process.
ok there is a quote straight from the hydrofarm website so I am finally feeling like things are moving forward
Q: Will my dual voltage 120/240v ballast operate on 208v?
A: Yes, all of our magnetic ballasts have a 208v lead coming out of the transformer located inside the ballast housing. You may have them specially ordered to operate 208v instead of 240v, or if you already have a Hydrofarm ballast, consult a certified electrician to rewire this for you. It is a very simple process.
ok there is a quote straight from the hydrofarm website so I am finally feeling like things are moving forward
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yep.
so now you just need to wire two hots to your control panel in order to input 208v. make sure they are on the same side of the panel and in sequential order.
glad it worked out well for you!
moresntoil
Member
the voltage to ground on a DELTA wild leg is 240 not 208, if you have a 3ph 208 service wild legs do not exsist due to the fact that they have a center tap wye neutral, with 240 delta there is no "center" tap so you need the center of a winding to be grounded to get a neutral for 120, but renders your high leg useless to ground but useable phase to phase....
...but yes good point bro, not trying to sound like a prick just want to share the love of electricity
its pretty easy to check. Put a meter hot to ground, you get 120. hot to hot you should get 208.
I have not checked the specs on those MLC's but I would bet heavily regardless of your voltage, 120,208 or 340, they will control it. Those MLC's should just be big switches/contactors
you just need to make sure the ballast is configured to the proper voltage
I have not checked the specs on those MLC's but I would bet heavily regardless of your voltage, 120,208 or 340, they will control it. Those MLC's should just be big switches/contactors
you just need to make sure the ballast is configured to the proper voltage
