Feeder sizing for feed thru panel

[fandi]

Hello All,
Please see attached picture. The feeder of 4#250kcmil is currently sized for 250A feeding two MLO panels P1 and P2. If both of the panels P1 & P2 would be loaded close to its 250A limit, would the feeder be overloaded? The reason I asked because what if the 250A feeder breaker of panel 'T1' did not work properly or later on someone replaced it with a 500A breaker to utilize more loads from P1&P2 combo. Thanks.

 

[ptonsparky]

If both panels are loaded to the 250 buss rating, panel one buss will be overloaded by 250 amp, the feeder will be overloaded and the EE should be fired or better, held accountable. That goes for the person putting in a 500 A breaker as well.

You can't worry about what may happen in the unforeseen future. That is above your pay grade.

 

[fandi]

If both panels are loaded to the 250 buss rating, panel one buss will be overloaded by 250 amp, the feeder will be overloaded and the EE should be fired or better, held accountable. That goes for the person putting in a 500 A breaker as well.

You can't worry about what may happen in the unforeseen future. That is above your pay grade.

So everything looked OK?

 

[Buck Parrish]

If both MLO panels combined load is less then 250 you're okay.

As far as installing a 500. Like Ptonsparky said. Then you would be getting in to "What If's" and that something we can not do. Other wise we would go crazy. You would just have to assume whom ever works on it in the future knows what they're doing. Some times , not very often but some times I'll leave a small note inside a panel to describe my set up, And of course the panels should be labeled, too. 110.16 (B

 

[ptonsparky]

NM

 

[electrofelon]

A brother in law could strike at anytime, there's nothing you can do about it.

 

[infinity]

Hello All,
Please see attached picture. The feeder of 4#250kcmil is currently sized for 250A feeding two MLO panels P1 and P2. If both of the panels P1 & P2 would be loaded close to its 250A limit, would the feeder be overloaded? The reason I asked because what if the 250A feeder breaker of panel 'T1' did not work properly or later on someone replaced it with a 500A breaker to utilize more loads from P1&P2 combo. Thanks.

The design is good. The OCPD is 250 amps, the bus is 250 amps, and the conductors are 250 amps, so nothing can be overloaded. The thought of someone changing the CB to 500 amps is highly improbable and maybe even impossible.