Interlocking as to not overload a 75kva

[Smart $]

Does unlikely have a diffrent meaning than cannot?

If so it should not mater who you talk to.

Should not, could not, would not doesn't matter....


... unlikely means the likelihood of occurence is nil or next to it.



People by their very nature may assign a different likelihood to the same scenario...


...and who are you to say they are wrong.

:jawdrop:

 

[justin13me]

I think this will work:
Timeclock1 pulls numerous NO poles closed when time. Closed contacts = lights on
TC1 also pulls numerous NC poles open disabling load 2.
TC2 can only allow current flow when 1 is not energizing contactor coils of load 1.
Timeclocks are in parallel and there is no way for both loads to be on at the same time

 

[justin13me]

I think this will work:
Timeclock1 pulls numerous NO poles closed when time. Closed contacts = lights on
TC1 also pulls numerous NC poles open disabling load 2.
TC2 can only allow current flow when 1 is not energizing contactor coils of load 1.
Timeclocks are in parallel and there is no way for both loads to be on at the same time

Sorry, please edit to:

I think this will work:
Timeclock1 pulls numerous NO poles closed when time. Closed contacts = lights on
TC1 also pulls a NC pole (from TC2) on an auxiliary relay, open disabling load 2.
TC2 can only allow current flow when 1 is not energizing contactor coils of load 1.
TC2 when time (NC aux) pulls in numerous NO contacts to turn on load 2.

 

[ptonsparky]

Sorry, please edit to:

I think this will work:
Timeclock1 pulls numerous NO poles closed when time. Closed contacts = lights on
TC1 also pulls a NC pole (from TC2) on an auxiliary relay, open disabling load 2.
TC2 can only allow current flow when 1 is not energizing contactor coils of load 1.
TC2 when time (NC aux) pulls in numerous NO contacts to turn on load 2.

Ladder diagram?

 

[iwire]

Yes. Unlikely = not probable to happen. Cannot = not possible to happen.

ofc that is assuming failsafe engineering and proper use of the terms in the first place.

It is unlikely that my home will burn down today due to the failure of a FPE breaker.

It would be impossible for my home to burn down due to electrical failure if I did not have an electrical service. I realize there are some incredibly far-fetched scenarios where this may happen, but for all intents and purposes it is so far beyond the realm of possibility as to be 0.

eta: interlocks are not intrinsically failsafe. I dealt with interlocked equipment for many years, and while they worked, you were not allowed to turn off a breaker to say the ash screw to the bin (last eqpt in the long chain of eqpt than must run) and use its interlock to shut off the bucket elevator; if you were working on the bucket elevator, its breaker must be secured.

would a lead/lag system work for the OP?

Again while I am talking code you are talking personal likes and dislikes. That is fine but the bottom line is the NEC uses the term 'unlikely' so physical interlocks not required.

 

[iwire]

Should not, could not, would not doesn't matter....


... unlikely means the likelihood of occurence is nil or next to it.



People by their very nature may assign a different likelihood to the same scenario...


...and who are you to say they are wrong.

:jawdrop:

I am saying it is wrong to look at 220.60 and state that section requires physical or electrcal interlocking.

Who am I to say so? A reader of the English language.

 

[Smart $]

Again while I am talking code you are talking personal likes and dislikes. That is fine but the bottom line is the NEC uses the term 'unlikely' so physical interlocks not required.

I am saying it is wrong to look at 220.60 and state that section requires physical or electrcal interlocking.

Who am I to say so? A reader of the English language.

Nothing wrong with your interpretation. :happyno:
But it amounts to nothing more than a personal opinion. :happyyes:

I'm not saying interlocking is required. Others may and do. They are not wrong either. A human mistake or programming error may make loads coincidental by accident. How does that weigh into 'unlikely'? Users choice IMO.

 

[iwire]

Nothing wrong with your interpretation. :happyno:
But it amounts to nothing more than a personal opinion. :happyyes:

I'm not saying interlocking is required. Others may and do. They are not wrong either. A human mistake or programming error may make loads coincidental by accident. How does that weigh into 'unlikely'? Users choice IMO.

I am sticking with 'they' are wrong using the NEC as justification, the words in the NEC do not support it.



We will remain in disagreement on this one.

 

[iwire]

220.60 Noncoincident Loads. Where it is unlikely that two or more noncoincident loads will be in use simulta-neously, it shall be permissible to use only the largest load(s) that will be used at one time for calculating the total load of a feeder or service.

 

[justin13me]

Line/ ladder (?) Diagram above.. I'm not too good with making drawings but I like to work it out this way to make sure things'll work out on site.
The 4 timeclocks control 2 rooms. Only 1 (same) room can be on at a time. Being inductive loads, one room turns on half, 10 minutes before the other half. When that happens it's not possible for the other room to be on, thanks to the auxiliary relays.
Hours later the first half turns off, then 10 minutes later the second half of the room (turns off). Then after about ten minutes, half the second room turns on then the other half another ten minutes later.
If for whatever reason the first room was to turn on; the second would turn off automatically (overide). The second room however can not overide the first but the interlocking /physically not possible part is still achieved.

 

[ptonsparky]

Line/ ladder (?) Diagram above.. I'm not too good with making drawings but I like to work it out this way to make sure things'll work out on site.
The 4 timeclocks control 2 rooms. Only 1 (same) room can be on at a time. Being inductive loads, one room turns on half, 10 minutes before the other half. When that happens it's not possible for the other room to be on, thanks to the auxiliary relays.
Hours later the first half turns off, then 10 minutes later the second half of the room (turns off). Then after about ten minutes, half the second room turns on then the other half another ten minutes later.
If for whatever reason the first room was to turn on; the second would turn off automatically (overide). The second room however can not overide the first but the interlocking /physically not possible part is still achieved.

Looks like it should work but you can drop to two time clocks by letting TC1 directly control RM1 1st half coil. Parallel a TDR1 with that coil and have the timed contacts control RM1 2nd half. Disadvantage being if TC1 fails open, no lights come On in Rm 1 or fail closed, they're always on.

Repeat for Rm 2.

Set the time clocks differently to achieve "unlikely" and add seriesed NC aux contacts to each RM1 contactor to "ensure" RM2 does not come On.

Repeat for Rm 2.

Metall Halide or HPS in a grow room? A few seconds delay would work otherwise.

 

[Smart $]

...
We will remain in disagreement on this one.

Actually, I agree with you. I just happen to know others that do not.

 

[kwired]

Should not, could not, would not doesn't matter....

I still do not like green eggs and ham

Sam I am.

 

[kwired]

Simple solution, manual double throw/transfer switch, needs a low pay employee to switch it every 12, 24, 48, or whatever hours though.

 

[don_resqcapt19]

I agree with Augie, in post #2. There is no reason to do anything other than provided the correct OCPD for the secondary conductors.

 

[Smart $]

I agree with Augie, in post #2. There is no reason to do anything other than provided the correct OCPD for the secondary conductors.

That puts you on the noncoincident loads side of the fence.

 

[ptonsparky]

I agree with Augie, in post #2. There is no reason to do anything other than provided the correct OCPD for the secondary conductors.

Very true. Code wants it done to a minimum safety standard. Nowhere does it say that the lights must turn On or Off. That is optional.

 

[don_resqcapt19]

That puts you on the noncoincident loads side of the fence.

I really don't have an issue with both loads being on at the same time. Based on the numbers given, the primary OCPD will clear before there is any damage. This assumes that the secondary conductors are protected per the one of the rules in 240.21(C).

 

[Smart $]

I really don't have an issue with both loads being on at the same time. Based on the numbers given, the primary OCPD will clear before there is any damage. This assumes that the secondary conductors are protected per the one of the rules in 240.21(C).

As I said, you are on the noncoincidental side of the fence. Otherwise, the installation is noncompliant, being improperly sized for the load.

 

[don_resqcapt19]

As I said, you are on the noncoincidental side of the fence. Otherwise, the installation is noncompliant, being improperly sized for the load.

I don't care if the load it twice as large as the supply...that is really a design issue and not a safety issue, but yes, the code rules would says that it is noncompliant if both loads are likely to be on at the same time.