Does a 208v plug need a neutral?

[mikeyv]

Hello all, I'm new here. Not sure if I'm posting in the correct section so forgive me if I'm not. I'm a 1st bracket union apprentice and have a couple questions in regard to a 208v or 240? I'm working on a commercial project (most of what we do is commercial/industrial) with a 3 phase 120v/208v system. Friday I was "making" up receptacles and ran across one of the plugs needing to be the top symbol that resembles a peace sign on the blueprint.

1) when working with a 3 phase system, is the plug to be 208v instead of 240v?

2) when "making up" the wires, does it need a neutral for the plug? I know it gets 2 legs for that roundhouse. I know a 240v residential plug does not need a neutral.

Thanks in advance,

Mike

 

[Dennis Alwon]

Most 3 phase systems are 208 but there is a 3 phase delta that is 240V.

In terms of the receptacle. They can be straight 208 single phase, 3 phase or single phase 208 with a neutral or 3 phase with a neutral.

 

[mikeyv]

Most 3 phase systems are 208 but there is a 3 phase delta that is 240V.

In terms of the receptacle. They can be straight 208 single phase, 3 phase or single phase 208 with a neutral or 3 phase with a neutral.

Hey Dennis, thanks for getting back to me. I'm still not sure how to make that box up then. Like I said, the print showed a symbol with a circle and inside was a peace sign. Tried to pasta picture here, but it was a .tiff file that is not supported. It needed two circuits but not sure if it needed a neutral. My main question is that: does this 208v plug need a neutral?

Thanks,

Mike

 

[mikeyv]

Most 3 phase systems are 208 but there is a 3 phase delta that is 240V.

In terms of the receptacle. They can be straight 208 single phase, 3 phase or single phase 208 with a neutral or 3 phase with a neutral.

Hey Dennis, thanks for getting back to me. I'm still not sure if the box I was going to make up needed a neutral - it is 3 phase and needed two circuits for the hots. As I said, on the print it had a circle with something resembling a peace sign inside - would have posted an image but all i could find was a .tiff file that is not supported.

Thanks,

Mike

 

[infinity]

Here are some NEMA standard receptacle/plug configuration charts so that you can familiarize yourself.

http://www.americord.com/nema-charts/

 

[Smart $]

... I'm working on a commercial project (most of what we do is commercial/industrial) with a 3 phase 120v/208v system. ...


1) when working with a 3 phase system, is the plug to be 208v instead of 240v?

...

Welcome to the forum(s) :thumbsup:

Kinda hard to make up a 240V plug if all you have is 208Y/120... :slaphead:

 

[Smart $]

Razzing aside, the plug and receptacle would likely be rated 250V.

 

[Sierrasparky]

Welcome Mike!:thumbsup:

 

[Rock Crusher]

In my brief experience, it depends on what the plug is for. If it has a neutral, it usually means there is some other elecronics involved. ie. a stove for the clock or dials, medical equipment for the displays.
But like I said, in my brief experience.
And btw, good luck with the apprenticeship.

 

[templdl]

Are you using a NEMA twist lock plug?
If you load does nt require 120v then a neutral is not required. You have L-L-L and an EGC.

ALso, this is a real nice chart to NEMA Plugs and recepticles.I would consider the 3pole-4wire grounding (not 3ph4w w/grd) then selecting the ampacity which you did not specify. Technically you could elect to use the 125/250 rating because the system voltage is less than 125v L-G since if most likele is a grounded 208Y/120 supply where the lione to ground voltage would be 120v.
NEMA L14-20
NEMA L14-30
NEMA L14-50
NEMA L14-60
The 250v rated plug and recepticle would be for a 240v delta where you would most likely have 240v from line to ground.

http://www.stayonline.com/reference-nema-locking.aspx

 

[mikeyv]

Are you using a NEMA twist lock plug?
If you load does nt require 120v then a neutral is not required. You have L-L-L and an EGC.

ALso, this is a real nice chart to NEMA Plugs and recepticles.I would consider the 3pole-4wire grounding (not 3ph4w w/grd) then selecting the ampacity which you did not specify. Technically you could elect to use the 125/250 rating because the system voltage is less than 125v L-G since if most likele is a grounded 208Y/120 supply where the lione to ground voltage would be 120v.
NEMA L14-20
NEMA L14-30
NEMA L14-50
NEMA L14-60
The 250v rated plug and recepticle would be for a 240v delta where you would most likely have 240v from line to ground.

http://www.stayonline.com/reference-nema-locking.aspx

I'm not sure what type of plugs they are using...I'm just in the making up phase and not trimming out devices. We're just splicing everything through at this point. I actually pig tailed the neutral out the other day for that plug and then realized just now that a neutral may not be required. I'm trying to get the knowledge here before asking my foreman.

So then the Y with circle around it indicates 208?

Thanks for the welcomes!

Mike

 

[templdl]

Mike,
Are you referring t o a figure on the chart that I referred to?
A circle with a line through if represents the word "Phase" which is normally preceded be a 3 for 3phase.
The, it is common to have a 3ph4w system with ground which is 208Y/120 w/grd for example but it doesn't have to be should 120v not be required. If so one could have 208v 3ph3w w/grd.

I hope that you have a good boss that doesn't intimidate you. A good boss will explain this to and teach you. You are asking some good questions.
The question to ask is if there any 120v L-N loads that need to be supplied. Might there be any added in the future if there aren't any to be fed at the present time? The, he may just tell you to run a neutral without any explanation. Then you jsut do it.

Dave

 

[mikeyv]

Mike,
Are you referring t o a figure on the chart that I referred to?
A circle with a line through if represents the word "Phase" which is normally preceded be a 3 for 3phase.
The, it is common to have a 3ph4w system with ground which is 208Y/120 w/grd for example but it doesn't have to be should 120v not be required. If so one could have 208v 3ph3w w/grd.

I hope that you have a good boss that doesn't intimidate you. A good boss will explain this to and teach you. You are asking some good questions.
The question to ask is if there any 120v L-N loads that need to be supplied. Might there be any added in the future if there aren't any to be fed at the present time? The, he may just tell you to run a neutral without any explanation. Then you jsut do it.

Dave

Hey Dave, here is the symbol I'm talking about which just designates 208Y - http://www.cfm.va.gov/til/sDetail/Div26Elec/SD260511-13.pdf it is the first symbol. 208v right?

Ok, so just to get to the bottom of this. Normally the 208v plug will not need a neutral unless it is for a clock or something 120v like a stove. I think it is some sort of appliance like a stove because it is in a food concession area. The 208v plug is similar to the 240v plug in that a neut is not needed.

Thanks,

Mike

 

[Smart $]

Hey Dave, here is the symbol I'm talking about which just designates 208Y - http://www.cfm.va.gov/til/sDetail/Div26Elec/SD260511-13.pdf it is the first symbol. 208v right?

Well according to that, the first symbol can represent any of 8 types of receptacles. See the list to the right. The letter at the beginning of each line is the designator to go with the symbol on the plan to indicate the type that goes there. For crude examples, (Y)A, (Y)E, (Y)G, etc.

Ok, so just to get to the bottom of this. Normally the 208v plug will not need a neutral unless it is for a clock or something 120v like a stove. I think it is some sort of appliance like a stove because it is in a food concession area. The 208v plug is similar to the 240v plug in that a neut is not needed.

First thing to get straight is, there is no normal. Unless you know for absolute certain, a questioning attitude is the only thing that should be normal. There are 8 types of receptacles that can be designated with that one symbol and only having the designator will narrow it down to one. From there, it gets wired as noted to the right of the designator letter.

Keep in mind, for new installations, one terminal is [almost] always for the EGC (embossed with a G in most cases). Look through the NEMA chart and find the receptacle having the number-letter combination at far right of the list: 14-60R, for example. Notice it has four terminals, G, X, Y, and W, and listed to left as single phase 125/250V. This receptacle would be wired, in your case, 208 (X to Y) with a neutral (W) and EGC (G) conductors.

 

[Smart $]

Also note the letter designator information lists poles and number of wires (3W or 4W). A single phase receptacle with a 3-pole 4W configuration is a tell that it gets a neutral.

 

[Dennis Alwon]

If that is the legend you have to work with then there must be one somewhere else that is more specific. Look on the plan where the specific outlet can be found and see if they say 3 wire 4 wire etc. I would expect it to either give the nema number or perhaps say 120/208-- this means there is a neutral. If it has just 208V then it should not require a neutral. If you are pigtailing the neutral there must be more than one of these recep. on the circuit. I would ask at the job site so you can learn how they knew a neutral was needed-- if it is needed.

 

[templdl]

Mike,
As this post continues one learns more about the application which is not unusual. I am to now understand it's for a heating appliance of some type. If so often times the different heat setting are based upon turning on multiple 120v elements and one does in a common 120/240 1ph3w residential range.
Dave

 

[Smart $]

If that is the legend you have to work with then there must be one somewhere else that is more specific. ...

Why?

The only time I would question the legend is if the wires spec'd on the plan didn't match the configuration noted in the legend... such as two hots, a neutral, and a ground running to a 3? 4W receptacle.

 

[mikeyv]

Wow thank you ALL for your informative replies! This site is awesome. I will check out the print tomorrow and also ask my foreman if the receptacle needs a 120 L-N load.

 

[Dennis Alwon]

Why?

The only time I would question the legend is if the wires spec'd on the plan didn't match the configuration noted in the legend... such as two hots, a neutral, and a ground running to a 3? 4W receptacle.

So when you see the first symbol on the plan what wires would you run-- there are 8 choices. Now if the plan has the first symbol and the letter next to it then I got it but I thought it was just the peace symbol