California plug, 50A per leg, etc.

Hi

Someone showed me a conversation and asked me if the information is okay. I couldn't really understand it and thought that should request you to help decipher it. Please have a look here. Could you make any sense of what is being said?

For you information, the system is star distribution with line-to-line voltage of 208 and line-to-neutral voltage of 120V.

Q1:
Perhaps, they meant CS6364C plug? CS6364C plug is a 3-pole 4-wire plug which, in my opinion, is a 3 phase plug. Please correct me.

This webpage mentioned several California plugs.

Q2:
What does it really mean? I think it means that each line can supply maximum of 50A current.

Here, "california connector" refers to CS6364C, in my opinion.

Q3:
I don't get where it says "so each plug uses 100 amps". What does it mean? If the plug is 3-phase one and each leg supplies 50A then shouldn't it be 150A?

Q4:
Why just 50A double pole breaker? Breaker's rating should be larger.

Thank you for the help in advance.

Regards
PG

My guess is that this is a conversation between two people with just enough knowledge to be dangerous.
Q1: Perhaps, they meant CS6364C plug? Yes. A simple case of dyslexia.
Q2: I think it means that each line can supply maximum of 50A current. Yes. It's a NEMA L14-50 plug. The 50 in the number stands for amps: 50 per phase. No idea where the "California" thing enters the picture.
Q3: I don't get where it says "so each plug uses 100 amps" This is where their lack of electrical knowledge begins to show. My guess is that they are using this to power something that normally requires 240 volts single phase plus neutral, and they are powering it from a 208 V 3 phase supply. So, they only need two phases and neutral. Sometime this is done with an electric stove when the mains supply is 120/208 3 phase. It works okay, but the stove doesn't get quite as hot.
Q4: Why just 50A double pole breaker? Perhaps the load is only 40A? There is no 40A connector, just 30 and 50. So they would have to go up to the next larger size which is 50A.

BobW said:

My guess is that this is a conversation between two people with just enough knowledge to be dangerous.
Q1: Perhaps, they meant CS6364C plug? Yes. A simple case of dyslexia.
Q2: I think it means that each line can supply maximum of 50A current. Yes. It's a NEMA L14-50 plug. The 50 in the number stands for amps: 50 per phase. No idea where the "California" thing enters the picture.
Q3: I don't get where it says "so each plug uses 100 amps" This is where their lack of electrical knowledge begins to show. My guess is that they are using this to power something that normally requires 240 volts single phase plus neutral, and they are powering it from a 208 V 3 phase supply. So, they only need two phases and neutral. Sometime this is done with an electric stove when the mains supply is 120/208 3 phase. It works okay, but the stove doesn't get quite as hot.
Q4: Why just 50A double pole breaker? Perhaps the load is only 40A? There is no 40A connector, just 30 and 50. So they would have to go up to the next larger size which is 50A.

Click to expand...

and what current flows in on one leg or prong must com out one of the other legs or be divided between the other 2 legs, so 40 in is also 40 out on the other leg or legs, they don't add.

Thank you, BobW.

BobW said:

Q1: Perhaps, they meant CS6364C plug? Yes. A simple case of dyslexia.

Click to expand...

So, they want to use CS6364C plug. I'm little confused about this. Please have a look here.

Q1:
i: In the conversation they are using the term plug to refer to CS6364C. Doesn't CS6364C a code for a 'connector' rather than a plug?
ii: I think that the connector goes into the inlet. Right?
iii: What is "IP60 Suitability"? Couldn't find any description on internet.

BobW said:

My guess is that they are using this to power something that normally requires 240 volts single phase plus neutral, and they are powering it from a 208 V 3 phase supply. So, they only need two phases and neutral.

Click to expand...

Q2:
So, they want to get 208V from the given wye/star 3 phase system. In my humble opinion, for this purpose, they can just use two hot wires and a ground conductor. Two hot wires will provide them with 208V. What's the need for neutral wire? For example, to get 240V from a home wiring like shown here only two hot wires are used which are 180 degrees out of phase with each other.

Q3:
I think that they were under the impression that having two hot wires (where it's 50A per leg) will give them double the current. Right?

Thank you for the help.

Regards
PG

References:
1: https://www.stayonline.com/reference-nema-locking.aspx
2: https://www.stayonline.com/reference-california-standard.aspx
3: Fundamentals of electric circuits by Alexander and Sadiku

Q1: IP60 is an environmental rating that tells how resistant the connection is to infiltration of dust and water. See: https://en.wikipedia.org/wiki/IP_Code
On the other hand the NEMA configuration type number simply defines the number and shape of the connector pins. The California designation may be a higher standard used there for weatherproof connectors. In the electrical trade the word "plug" often has the opposite meaning to what we are familiar with. Many times I've heard electricians use "plug" when referring to a what most of us call a receptacle. So, you can't rely on the meaning of the word "plug" without additional information.

Q2: Going back to my electric stove example, the equipment probably has a combination of 208V and 120V loads. For example, the heating elements on the stove are 208 (240) but the clock is 120V. So, you need the neutral to provide for the lower voltage part of the load. You can't use the ground for that. It's not legal. That's why they chose a connector that has the neutral pin as well as the ground pin. (It's also not legal to use a spare line pin for neutral. Neutral must only be run through a defined neutral pin.)

Q3: Yes, they just added up 50A per phase and came up with 100A, which is wrong, but an easy mistake to make.

Thank you, BobW.

Q1:
In the post above, I said that for a NEMA L14-50 plug (or, CS6364C plug) each line can supply maximum of 50A current. I don't think that what I said is really correct. In my opinion, it should mean that the material NEMA L14-50 plug is made of can handle maximum current of 50A per leg.

Further, it shouldn't be taken to mean that the system can only supply 50A of current per line/leg because current is dictated by resistance or impedance of a load.

Note to self: In a 3 phase system each phase voltage differ from the other by 120°. Also the line voltages lead their corresponding phase voltages by 30°.

Q2:
I was looking at 3 phase NEMA plugs here and I couldn't find neutral terminal, i.e. "w", in any one of them. I understand that delta 3 phase system doesn't have any inherent neutral wire therefore for a delta system such plugs are okay. But a star system has an inherent neutral wire and it can used especially in case of unbalanced load although star system can also work without a neutral

Thanks a lot for the help.

Regards
PG

Reference:
1: https://www.stayonline.com/reference-nema-locking.aspx

Q2: I didn't really look all that closely at the number of pins in the connector that you originally posted. However, there is a 3 phase 5 wire connector with the 3 phases and both neutral and ground. It's a NEMA L21-50, and would be appropriate for a 3 phase application where neutral is needed. It's shown near the bottom of this page:
https://www.stayonline.com/reference-nema-locking.aspx

So, if they don't need the neutral to provide for 120V loads, then they would only need a connector that has the line (phase) pins and a ground.

Thank you.

And please don't mind my asking, is that what I said Q1 correct? Thanks.

This is a side question. Personally I don't have any experience with 3 phase loads. Suppose a 3 phase load comes with three line terminals, one neutral and one ground, and the electric supply doesn't come with a neutral wire. I ignore the neutral terminal of load and connect its line terminals and ground to the supply, will it cause any problem? In other words, do 3 phase loads which has neutral terminal differ from the ones who don't have one?

Regards
PG

Yea, nasty topic. I know this discussion is about 3 phase, but to illustrate some confusion, I'll talk about 240 single phase or split-phase in the US.

Ok, we talk about 200 A service. It means 200A at 240 V. It ALSO means 400 A at 120 V. It also means the Neutral wire takes the difference of the loaded legs and can have effective "opposite signs".

What people do is add up the breaker values and that's totally wrong. With sub-panels, the main breaker could be 200A and the panel could only support 40A. It's legal to do so if the feed is protected at 40 A. Sub-panels don;t have to be main-breaker. Again, confusion.

In the home we have dryers and stoves which could use plugs. The water heater and the AC usually don;t. They use disconnects. Some outdoor disconnects have the facility to incorporate a 120 V outlet. It would actuallly be fed from a separate circuit.

The electric water heater normally operates on 240 V with a ground and is hard wired. All it has is a 240 VAC resistive element and ground. Now, it probably requires a disconnect within 3 feet.

With electric dryers we start to have problems because they were initially 3 wire and the wrong three wires. See this: https://www.electriciantalk.com/f2/dryer-plugs-3-4-prong-38228/

So with 240 single phase (split phase) L1 L2 and ground are mandatory. Neutral SHOULD be the optional one.

Confused?

In some equipment I made, I used a twist lock on the instrumentation back that could either be 120 or 240 VAC and the rack had mixed equipment on it.

On a different RACK system, we actually attached a main breaker panel to the rack and plugged it into the wall with a 60 A, 240 V 4 wire plug.

Here's https://en.wikipedia.org/wiki/NEMA_connector a verbal description of the various plugs. To me the L18 is very odd and the L21 makes much more sense. The L15 makes more sense than the L18.

Some of the plugs may be essentially from an earlier time where Ground didn't really exist. There, at one time, existed a non-polarized 120 V receptacle. I may even have one somewhere where both prongs were narrow, Houses at one time were wired knob and tube. https://en.wikipedia.org/wiki/Knob-and-tube_wiring

The house I live in was built in the 1960's, so a fiberglass covered Romex (NM) was used, Now we have yellow themoplastic jacketed to (20 A, 12 AWG) and white jacked cable (14 AWG, 15A) They are sold as 14/2 with ground. The ground is a bare conductor and of a lower ampacity. The original outlets all lack the threaded green ground screw hole.

Code says that the metal box, if used, and the outlet has to be bonded to ground. There is a special outlet where the requirement does not have to be followed, but for all intents and purposes, it does. It tales all sorts of contortions to make the grounding happen.

I usually undo the ground connections to the box, which was to a Romex clamp and take a piece of solid to a ground clip. Then I use an integrated wirenut/stranded pigtail and U terminal to screw all of those together, Usually two Romex grounds, and the solid green wire to the ground clip. The pigtail exits 180 degrees from the normal wire side of a wirenuts. These are made by Ideal as Term-a-nuts.

I like to wire Hot/N and ground using the stranded Term-a-nuts of the proper color. https://www.idealindustries.ca/products/oem/twist-on/term-a-nut_pigtail.php Usually the outlets are daisy chained.

I think all of them have been replaced. One room I wired with Tamper Resistant receptacles when it got painted. These are inherently "kid safe". You have to stick something in both Hot and Neutral at the same time to allow entry.

The bottom line is standards have evolved.

EDIT: Minor corrections

I saw IP was forgotten. Lok up "Ingress Protection" Each digit has a meaning.

EDIT: https://en.wikipedia.org/wiki/IP_Code