When L21-30 just isn't big enough
- Thread starter Rick Stansby
- Start date
Re: When L21-30 just isn't big enough
You are so helpful! Thank you so much!!
You are so helpful! Thank you so much!!
Re: When L21-30 just isn't big enough
I got to thinking, if you feed an amp rack with 4 L530's they each go back to their own breaker right? The only difference with the L14-30 would be sharing a neutral and ground. Which with an L5-30 the neutral and ground is also shared in the panel. So really no difference?
I got to thinking, if you feed an amp rack with 4 L530's they each go back to their own breaker right? The only difference with the L14-30 would be sharing a neutral and ground. Which with an L5-30 the neutral and ground is also shared in the panel. So really no difference?
Re: When L21-30 just isn't big enough
The neutral and ground are only bonded at the service entrance.
Re: When L21-30 just isn't big enough
Nobody said anything about bonded, And no they are not always bonded at the SE entrance.
what I said was that the difference between running 4-L530's, and 2 L14-30's is that you are sharing a ground and neutral in one cable with an L14-30. If you run 4 L530's you are still sharing them in the panel. I'm having a hard time putting this into words that everyone can understand.
Nobody said anything about bonded, And no they are not always bonded at the SE entrance.
what I said was that the difference between running 4-L530's, and 2 L14-30's is that you are sharing a ground and neutral in one cable with an L14-30. If you run 4 L530's you are still sharing them in the panel. I'm having a hard time putting this into words that everyone can understand.
Re: When L21-30 just isn't big enough
I will take shot at it.
Only YOU know what your use of a connecter is. There is no way for the circuit breakers to know if there are just 120v things connected or that a 240v thing is connected. It would be dangerous if on an overload it only tripped one side of the line as it would leave voltage still on other pins of the connector. Depending on the use, it could kill someone.
Your example isn't the same at all because of way the circuits are protected. A L5-30 is considered a circuit as is a L14-30. The circuit has a single disconnect.
Also, the code does require bonding or ground and neutral at one and only one location. See Article 250.24 of the NEC for a full explanation. The usual case is to bond in the service panel connected to the service drop after the meter.
I will take shot at it.
Only YOU know what your use of a connecter is. There is no way for the circuit breakers to know if there are just 120v things connected or that a 240v thing is connected. It would be dangerous if on an overload it only tripped one side of the line as it would leave voltage still on other pins of the connector. Depending on the use, it could kill someone.
Your example isn't the same at all because of way the circuits are protected. A L5-30 is considered a circuit as is a L14-30. The circuit has a single disconnect.
Also, the code does require bonding or ground and neutral at one and only one location. See Article 250.24 of the NEC for a full explanation. The usual case is to bond in the service panel connected to the service drop after the meter.
Re: When L21-30 just isn't big enough
You are talking about separating the 120V circuits into 4 cables instead of having the capability of using 240V from one cable.
The difference is that if you choose to run anything in your rack on 240V and 120V simultaneously, than you cannot do it with 4 530's. Also, you are using extra neutral wire, increasing weight.
Using a 240V/120V system, the triplen currents in the neutral are 120 degrees out of phase, giving you the option of running 2 simultaneous loads on a single neutral cable because they occur at different times. When you use all L530's, every individual neutral must carry all the current supplied by the hot.
If it was my system, I would use a california connector wired 208 three phase, not 240/120. That would get you 3 phases of 208 at 50A, but no 120v capability. I believe the number is different than cs6365/4.
You are talking about separating the 120V circuits into 4 cables instead of having the capability of using 240V from one cable.
The difference is that if you choose to run anything in your rack on 240V and 120V simultaneously, than you cannot do it with 4 530's. Also, you are using extra neutral wire, increasing weight.
Using a 240V/120V system, the triplen currents in the neutral are 120 degrees out of phase, giving you the option of running 2 simultaneous loads on a single neutral cable because they occur at different times. When you use all L530's, every individual neutral must carry all the current supplied by the hot.
If it was my system, I would use a california connector wired 208 three phase, not 240/120. That would get you 3 phases of 208 at 50A, but no 120v capability. I believe the number is different than cs6365/4.
Re: When L21-30 just isn't big enough
You know what Ill just give up since you guys are not understanding what I am saying. Like I said I have a hard time putting it into words. I know whats going with my gear and thats all that matters to me. Electrical inspectors that have inspected my distro's many of times have also found no fault in how I am doing what I do.
Peace out.... I got shows to go pack for with my fucked up wiring....
You know what Ill just give up since you guys are not understanding what I am saying. Like I said I have a hard time putting it into words. I know whats going with my gear and thats all that matters to me. Electrical inspectors that have inspected my distro's many of times have also found no fault in how I am doing what I do.
Peace out.... I got shows to go pack for with my fucked up wiring....
Still from my phone here...
The codes apply to a variety of circumstances, against a variety of possible dangers. One such danger with mwbc's in regular wiring is that a breaker can be turned off but the neutral can still be carrying electricity for the other circuit. If you disconnect the neutral and something is turned on upstream to the still energized circuit, the upstream neutral can use your body (perhaps your left hand to right hand - across the heart) to reach the downstream neutral.
You may never do this, but the code is there for a reason.
Re: When L21-30 just isn't big enough
Finally someone answered my question! You are right though probably will never happen. Thanks for explaining and not just throwing Code numbers around like others...
Finally someone answered my question! You are right though probably will never happen. Thanks for explaining and not just throwing Code numbers around like others...
Re: When L21-30 just isn't big enough
I am sorry you feel that way. I provided the code references to you as a courtesy in case you wanted more in depth explanation. I explained as good as I could (but you diss me anyway).
By the way, I don't recall anyone saying your gear isn't right.
Have a great day.
I am sorry you feel that way. I provided the code references to you as a courtesy in case you wanted more in depth explanation. I explained as good as I could (but you diss me anyway).
By the way, I don't recall anyone saying your gear isn't right.
Have a great day.
Re: When L21-30 just isn't big enough
The difference between multiple, single leg connections and a connector or wiring device with more that ONE hot leg is exactly that. In your example, EACH hot leg is protected, but there is only one hot leg per connector or wiring device. Code requires common trip for circuits that present more than one hot leg in a connector or wiring device. It's a life safety thing to prevent a person from being electrocuted while performing trouble shooting or service. The idea is that ALL hot conductors for each circuit open together.
If you don't grok that concept I'm not sure how else to explain it other than referring you to the Code itself... and I'd suggest you begin with NEC Chapter 2 and Chapter 3.
The difference between multiple, single leg connections and a connector or wiring device with more that ONE hot leg is exactly that. In your example, EACH hot leg is protected, but there is only one hot leg per connector or wiring device. Code requires common trip for circuits that present more than one hot leg in a connector or wiring device. It's a life safety thing to prevent a person from being electrocuted while performing trouble shooting or service. The idea is that ALL hot conductors for each circuit open together.
If you don't grok that concept I'm not sure how else to explain it other than referring you to the Code itself... and I'd suggest you begin with NEC Chapter 2 and Chapter 3.
Re: When L21-30 just isn't big enough
The Code is quoted because absent any local variations it IS the Code. I anticipate those posting the Varsity forum to be capable of reading the Code on line or at a public library.
In the example Marlow provides, not only is there current on the neutral of a circuit with an open hot leg, the other leg is still HOT. While you might think this is a good thing (only part of your gear goes down), it's not safe.
The Code is quoted because absent any local variations it IS the Code. I anticipate those posting the Varsity forum to be capable of reading the Code on line or at a public library.
In the example Marlow provides, not only is there current on the neutral of a circuit with an open hot leg, the other leg is still HOT. While you might think this is a good thing (only part of your gear goes down), it's not safe.
Re: When L21-30 just isn't big enough
Scott,
In the Varsity forum we do things to code. Code mandates linked breakers for the type of service you are talking about.
If you want to talk about building and using a non-code electrical distribution panel do it in DIY. Certainly the risk is low, but there is a right way and a wrong way. The varsity forum is for the most correct and legal way.
Scott,
In the Varsity forum we do things to code. Code mandates linked breakers for the type of service you are talking about.
If you want to talk about building and using a non-code electrical distribution panel do it in DIY. Certainly the risk is low, but there is a right way and a wrong way. The varsity forum is for the most correct and legal way.
Silas Pradetto
Graduate Student
Re: When L21-30 just isn't big enough
You could die. And that's enough reason for the NEC to read like it does.
You could die. And that's enough reason for the NEC to read like it does.
Re: When L21-30 just isn't big enough
I was going to leave this alone until I saw an idiot comment like this one. This isn't my first rodeo dude...
I was going to leave this alone until I saw an idiot comment like this one. This isn't my first rodeo dude...
Silas Pradetto
Graduate Student
Re: When L21-30 just isn't big enough
Scott, I know that, we've met, you know what's up. I just thought of a scenario that helped me picture things:
There are two amplifiers connected to an L14-30 circuit. One is across both hots, and the other is hot to neutral. Something happens where the 120V wired amplifier trips it's circuit, but rather than the whole L14-30 going down, only half does. The amp wired for 240 volts is not seeing a complete circuit anymore, so it shuts off.
What someone might not guess is that the the hot of the 240V amplifier on the tripped leg is still probably hot--it's just waiting to see a path to ground or somewhere else to complete the circuit, because it's drawing through the 240V amplifier.
To make things worse: I can't think of a problem scenario where the ground stays intact, so let's say the ground on the whole rack is missing. And let's say that when the other amplifier died, it shorted hot to the chassis. Now the whole rack is hot, but it looks like everything is off, and it's half tripped. Next person to touch the rack gets severely shocked or dies.
Probably not a likely scenario, but I'm also trying to bend my mind around situations where this would be deadly, and I think the main problem is going to be that voltage will be where it's unexpected if only half the connector shuts off.
I hope this helps, I wasn't trying to leave you an idiot comment.
Scott, I know that, we've met, you know what's up. I just thought of a scenario that helped me picture things:
There are two amplifiers connected to an L14-30 circuit. One is across both hots, and the other is hot to neutral. Something happens where the 120V wired amplifier trips it's circuit, but rather than the whole L14-30 going down, only half does. The amp wired for 240 volts is not seeing a complete circuit anymore, so it shuts off.
What someone might not guess is that the the hot of the 240V amplifier on the tripped leg is still probably hot--it's just waiting to see a path to ground or somewhere else to complete the circuit, because it's drawing through the 240V amplifier.
To make things worse: I can't think of a problem scenario where the ground stays intact, so let's say the ground on the whole rack is missing. And let's say that when the other amplifier died, it shorted hot to the chassis. Now the whole rack is hot, but it looks like everything is off, and it's half tripped. Next person to touch the rack gets severely shocked or dies.
Probably not a likely scenario, but I'm also trying to bend my mind around situations where this would be deadly, and I think the main problem is going to be that voltage will be where it's unexpected if only half the connector shuts off.
I hope this helps, I wasn't trying to leave you an idiot comment.
Re: When L21-30 just isn't big enough
I had a rough day, I should not have said idiot comment. Sorry bout that. Really don't want to talk about this topic anymore, but I do see your point. We don't run any amps at 240v.
I had a rough day, I should not have said idiot comment. Sorry bout that. Really don't want to talk about this topic anymore, but I do see your point. We don't run any amps at 240v.
Re: When L21-30 just isn't big enough
Neutral imbalances, electrical fires, electrocution... pshaw! I'll just make sure the rider specifies a fire extinguisher with a Class C rating and carry an AED.
Neutral imbalances, electrical fires, electrocution... pshaw! I'll just make sure the rider specifies a fire extinguisher with a Class C rating and carry an AED.