How is 208 volts different than 230/240 volts?

In this quick video Bryan talks How is 208 volts different than 230/240 volts.

Read all the tech tips, take the quizzes

[sergiobost]

Concise and dense with knowledge. Liked.

[jizzwad]

No one has been able to explain this to me and get it through to my simple brain the way that you just did. Thank you!!!!

[brucevrooman]

You explained this subject better than I was taught in 10 months of trade school. Thanks !!

[googacct]

I am not an HVAC tech, but do a bit of electronics. I had always been a bit confused about the 208 versus 240, but now I understand why there is difference. Thanks for the quick and clear explanation.

[triangledetecting]

Thanks that explains it pretty well. I was in a panel or a three phase disconnect trying to figure out how to put a single phase unit and only get about 211 V off of two legs. Yours was the first video to explain what was going on.

[SavedByFaithInJesus]

I'm an electrician, Thank You for this video, you cleared up some questions I didn't know I had.

[jmiller]

208 can only be obtained from a 3-phase wye system. 240 volts can be obtained from either a 120/240 residential system or a 240 volt 3-phase delta system.

[HVACRCERTIFIEDTRAINING]

Congratulations You have a special talent to communicate the most important factors in the HVAC industry, not all technicians are electricians and electricians are not always technicians, in this field you must have holistic qualities, that is, knowing how to do everything !!! Thanks for the incredible contributions from your school and your channel.

[toofastws]

Great video, I've been doing hvac for 14 years and still learning new things everyday.

[jeffhival]

In a 240volt /120 volt spilt phase system the phases are absolutely not 180 degrees out of phase. The winding of that transformer is wound the same direction from L2 to the center tapped neutral and from neutral to L1 hence no change in phase relationship. If the transformer winding was wound one direction from L2 to neutral and wound the opposite direction from neutral to L1 then you would have 2 120 volt sine waves that are 180 degrees out of phase from each other but you would have no voltage available when measured from L1 to L2. You would have 120 volts from neutral to L2 and 120 volts from neutral to L1 and u could power 120 volt loads off of these but when you hook up a load across L1 and L2 you are going to find that there is not 240volts available. There is zero voltage. The reason why these sine waves appear to be 180 degrees out of phase is because the oscilloscope leads were not hooked up correctly to show the actual relationship of the signals. It is the same thing as hooking up a multimeter to a 12 volt dc car battery backwards. If you touch the black lead of the meter to negative and the red lead to the positive then the meter show a positive voltage but if you reverse the meter leads on the battery the meter displays a negative voltage. For anyone who doesn't believe and wants to be properly educated go over to Dave Gordon's youtube channel and find the video on 120/240 volt systems that describes what I am saying in great detail with a live demonstration board absolutely proving that it is not electrically possible for the phases to be out of phase and have L1 and L2 add up to 240 volts and power a load.

[Ghostman]

Thank you very much! Your an expert here and I got a lot of info from you that I needed concerning wiring my air compressor. Wish I had your understanding of this voodoo we call electricity 😕 lol. Thanks again man.

[SA-buev]

i thought this video gets straight to the point and this guy did a great job. Thank you

[spencernoseworthy]

You explained this really well and kept it concise, thank you.

[extremekilla]

I learned this lesson the hard way when I told the hvac company 230v exhaust fans were good for our welding shop . We have 120/208 coming off a 480v panel to transformer. Needles to say i ordered a few buck boost transformers.

[ymjjdpq]

First time this ever made any sense! Thank you

[stevenweber]

Thank you. helped allot. you are going to make me sound like i know what im talking about at work tomorow.

[Sparky-wwre]

Many apartments and townhouses will have 120/208Y 3ø. Each unit, however, will be fed the two legs out of three, and of course your neutral and ground, and will alternate between A-B, A-C, & B-C so as to balance the loads. It's more efficient than a single phase service but of course can present problems with motors as you described. The electric range and dryer will have 75% power for heating.

[devindecater]

Thank you. I noticed this and was wondering. I have solar on my house and regularly see 250-257 when the sun is shining direct. It’s less than ideal for my CNC controls, I’ve blown a few capacitors and servo drives.

[freguy]

I’m interested in your backstage demonstration setup, looks like something that could be built to get visuals on all sorts of things and on top of that do electrical tests, is it up anywhere?

[jkbrown]

The "old" voltages are the plus or minus range on the nominal voltage. Lower stamped on load devices, higher on switches and things. Some areas only at nominal, say 120V, +/- 10% which ranges from 130-110, =/-5% from 125-115. Now North America has +/-5% and it's generally baked in on modern devices given the good control of the grid. Might also be what the meters read in the past as well.