Maximum total amps allowed

[rookie4now]

I was just wondering something. I saw a service yesterday that had a four-gang meter socket (horrizontal) and there were four panels below, one for each unit. Nothing special. then I noticed that it was fed with #1 awg copper. Again no big deal. The thing I'm wondering is that ALL 4 panels had a 125a breaker. That's a total of 500 amps. I realize that each individual unit is breakered at the appropriate amperage, but it seems pretty realistic to think that each unit might draw 50 amps at the same time and then there would be 200a flowing on #1 awg.

How does the NEC address this? There must be some maximun...right?

 

[pete m.]

Article 230.90 exception 3 might address this installation.

 

[rookie4now]

Article 230.90 exception 3 might address this installation.

Hmm. Seems pretty lenient. What if they install bigger electric appliances later? Sure seems like a a major thing to be so lax on.

 

[pete m.]

Hmm. Seems pretty lenient. What if they install bigger electric appliances later? Sure seems like a a major thing to be so lax on.

I agree.... but, I would say that we have to assume that a "qualified person" would check the ampacity of the service conductors prior to adding any additional load. Also, 90.1(b) recognizes that this installation may not be "....efficient, convenient, or adequate for good service or future expansion of electrical use."

Pete

 

[tryinghard]

...I realize that each individual unit is breakered at the appropriate amperage, but it seems pretty realistic to think that each unit might draw 50 amps at the same time and then there would be 200a flowing on #1 awg.

How does the NEC address this? There must be some maximun...right?

NEC address' it specifically in Articles 220 & 230, proper load calculations "calculated load" determines the service and distribution. Notice examples in Annex D

 

[LarryFine]

Hmm. Seems pretty lenient. What if they install bigger electric appliances later? Sure seems like a a major thing to be so lax on.

One could say the same thing about, for example, a central AC unit. The existing one may only require #12, say, but what if a replacement requires #10?