Selective Coordination

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fauxfly

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I was at a code class this week and one of the puttin this on was a engineer from the state. He went on for about an hour and a half about how this type of work is to be done...the calcs, circuit lenght, primary V, secondary V, tons of other things that quite frankly lost me for most of the time.

I understand how breakers operate and how a one line diagram is to be layed out and how to read it, my question is that in the past I've allways looked to the EE on site, to verify that breakers are what they need to be as far as their AIR rating.

This is new to me, you guys have any thoughts on this, et me know.

Steve
 
fauxfly said:
I was at a code class this week and one of the puttin this on was a engineer from the state. He went on for about an hour and a half about how this type of work is to be done...the calcs, circuit lenght, primary V, secondary V, tons of other things that quite frankly lost me for most of the time.

I understand how breakers operate and how a one line diagram is to be layed out and how to read it, my question is that in the past I've allways looked to the EE on site, to verify that breakers are what they need to be as far as their AIR rating.

This is new to me, you guys have any thoughts on this, et me know.

Steve
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Hang in there, Fauxfly, your not always going to retain everything from those types of courses. Learn as much as you can and it will be easier next time.
 
Sorry guys

My OP did'nt do my thoughts justice. My question is do electricians out in the field do a lot of this kind of thing, this seems to be the first few steps of the arc fault calcs. Nothing to do maintenance/installation. I'm just wondering if you guys are starting to see this and how concerned are you about it.
 
fauxfly said:
Sorry guys

My OP did'nt do my thoughts justice. My question is do electricians out in the field do a lot of this kind of thing, this seems to be the first few steps of the arc fault calcs. Nothing to do maintenance/installation. I'm just wondering if you guys are starting to see this and how concerned are you about it.
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OK good question, usually on new construction projects the engineering design group will review it to assure it complies, and yes it is important how the breakers are set to assure they open in the proper steps.

Nothing to do maintenance/installation?

Maintenance electricians may be asked to check why a main switch is opening and the downstream breakers are not opening, is it the design, wrong settings, or poor coordination.

Something good to know, but it is usuall built into any good design.
 
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I agree with Satcon here.. You may never have to design it but you need to know it..Say you are a new hire and doing maintenace at a plant and you replaced a technician who retired..the technician had worked his way through the ranks and became an electrical tech at the plant..he had a breaker blow up and just used what he had on the self to repair it..He never understood these issues and now they have some freaky issues every now and then..knowing your trade the best you can will help you recognize this very real potential hazard..So knowing this stuff is good for your safety as well as the betterment of your company..Learning it can only be to your betterment..
 
cschmid said:
I agree with Satcon here.. You may never have to design it but you need to know it..Say you are a new hire and doing maintenace at a plant and you replaced a technician who retired..the technician had worked his way through the ranks and became an electrical tech at the plant..he had a breaker blow up and just used what he had on the self to repair it..He never understood these issues and now they have some freaky issues every now and then..knowing your trade the best you can will help you recognize this very real potential hazard..So knowing this stuff is good for your safety as well as the betterment of your company..Learning it can only be to your betterment..
Click to expand...

Excellant discription of a likely situation.
 
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