120% rule for busbar rating for a meter socket load center

Status
Not open for further replies.
jaggedben said:
The Siemens I'm not getting any google results for. Typo?

I don't think the rating of the branch circuit OCPDs affects anything here. Your 40A continuous loads would need to be on 50A breakers. But you could have five of them, in the Millbank
Click to expand...

ahh, just realized that I left off the Y. Sorry …
The Siemens spec sheet for MC2440B1200CEY
 
Carultch said:
I suspect this is misleading marketing. It sounds like it is a rating that could work in theory, but good luck making it work in practice.

The product may have a continuous load rating as it ships to you from Milbank, but the problem is that I don't see any specifics on the intended product family of branch breakers. This leads me to believe that you are on your own to source the breakers. The 210.20(A) exception that allows continuous ratings in the first place, requires that it is an entire assembly be listed for continuous duty, in order to take credit for the continuous duty rating.

If you source a 3rd party branch breaker that isn't listed in a combination with the panelboard for continuous duty, then you lose the continuous duty rating of the panelboard assembly.
Click to expand...

I agree with your assessment - thanks. I'll reach out to their tech support and ask them to ask if they sell a continuous duty breaker. Also want to know if the busses are crated continuous because more than likely only the socket is continuous.
 
JoeStillman said:
The main in that Milbank panel is a fuse pullout.
Click to expand...
Thanks.
However, in order for the city planner to approve me to install five 40A receps for EV continuous usage, the complete panel including the installed five 50A OCPD need to be rated (and labeled) continuous usage. Right?
 
AreGee said:
Thanks.
However, in order for the city planner to approve me to install five 40A receps for EV continuous usage, the complete panel including the installed five 50A OCPD need to be rated (and labeled) continuous usage. Right?
Click to expand...
I know of no UL listed protective device, below a 200A frame size, that is rated for 100% when mounted in an enclosure.
 
AreGee said:
Thanks.
However, in order for the city planner to approve me to install five 40A receps for EV continuous usage, the complete panel including the installed five 50A OCPD need to be rated (and labeled) continuous usage. Right?
Click to expand...
Why would you need a 100% rating for the 50 A devices? If the loads are 40A continuous, 40*1.25=50.

For the 200A device too, you are at 160A*1.25=200.
 
suemarkp said:
The load calcs take continuous into account, so if a load calc comes to 400A, then a 320/400A meter should be fine.
Click to expand...
Correct me if I am wrong here;
230.31(A) Covers service conductor ampacity, 408.30 Covers panelboard ampacity and I am failing to find the code reference for adding 125% to continuous loads to service conductors or panelboards.
Its not in 220.40 (the general calc) where 230.32(A) send you
Yes feeders do 215.2 branch circuits do.
Service conductors & panels I fail to see.
discussing this also in another thread
 
gene6 said:
Correct me if I am wrong here;
230.31(A) Covers service conductor ampacity, 408.30 Covers panelboard ampacity and I am failing to find the code reference for adding 125% to continuous loads to service conductors or panelboards.
Its not in 220.40 (the general calc) where 230.32(A) send you
Yes feeders do 215.2 branch circuits do.
Service conductors & panels I fail to see.
discussing this also in another thread
Click to expand...
Underground and overhead service conductors do not have the 125% requirement, but service entrance conductors do. See 230.42.
 
jaggedben said:
A panelboard is most often part of a feeder. The definition of a feeder is expansive and not limited to wire type conductors.
Click to expand...

There is some debate about whether that is the intention of the code, that a 125% feeder sizing rule applies to a panelboard buss. 310.1 does say that that article does not apply to conductors that form an integral part of equipment. The "conductor" used in the definition of "feeder" could be a more broad use of conductor and not limited to article 310 conductors I suppose.
 
electrofelon said:
There is some debate about whether that is the intention of the code, that a 125% feeder sizing rule applies to a panelboard buss.
Click to expand...
Pretty sure I agree with jaggedben, but isn't it moot? In that a panelboard is always protected by an OCPD, and if that OCPD is not 100% rated, it will need to be sized at 125%, and so the bus will be sized at 125%. Conversely, if the OCPD is 100% rated, then the bus rating is always continuous, so no 125% factor required for the panelboard.

BTW, since you're quite familiar with Siemens "true" panelboard catalog, can you get them with a 100% rated main breaker? Seems like all it would require in terms of construction is possibly extra space around the main breaker.

Cheers, Wayne
 
wwhitney said:
Pretty sure I agree with jaggedben, but isn't it moot? In that a panelboard is always protected by an OCPD, and if that OCPD is not 100% rated, it will need to be sized at 125%, and so the bus will be sized at 125%. Conversely, if the OCPD is 100% rated, then the bus rating is always continuous, so no 125% factor required for the panelboard.

BTW, since you're quite familiar with Siemens "true" panelboard catalog, can you get them with a 100% rated main breaker? Seems like all it would require in terms of construction is possibly extra space around the main breaker.

Cheers, Wayne
Click to expand...
I agree it is somewhat of a moot point, because of 408.36 the panel board bus rating would have to tag along with the breaker rating. But as you say there is the 100% breaker ahead of the panel board case, but I think the panelboard bus could again tag along with the exception for being part of a 100% assembly? Is that the way you see it too?

I don't see why you couldn't get a panel board with a 100% rated main breaker but I don't think it could be used at the 100% level My understanding is to achieve the 100% rating a breaker needs to be mounted in a separate enclosure whose size is specified by the manufacturer, and there cannot be any more over current devices in that enclosure.
 
electrofelon said:
But as you say there is the 100% breaker ahead of the panel board case, but I think the panelboard bus could again tag along with the exception for being part of a 100% assembly? Is that the way you see it too?
Click to expand...
Yes, if you have a 100% rated OCPD in its own enclosure supplying an MLO panelboard whose bus rating matches the OCPD rating, I believe that is all copacetic. If the panelboard bus is part of the feeder supplied by the 100% rated OCPD, then per the exception it does not need a 125% rating.

electrofelon said:
My understanding is to achieve the 100% rating a breaker needs to be mounted in a separate enclosure whose size is specified by the manufacturer, and there cannot be any more over current devices in that enclosure.
Click to expand...
That is what I've always heard, but looking at that picture of a true panelboard from the other thread, the enclosure seemed so large that it wouldn't actually be a problem to provide the necessary air space around the 100% rated breaker, or even to provide a barrier that divides the enclosure into two compartments, with the 100% rated main breaker in its own compartment of sufficient size. So I'm wondering if either of those is a possibility.

Cheers, Wayne
 
jim dungar said:
I know of no UL listed protective device, below a 200A frame size, that is rated for 100% when mounted in an enclosure.
Click to expand...
Siemens new 3VA series offers a 150A frame that goes down to 40A:

All 3VA61 electronic trip circuit breakers are available with 100% ratings. To order, change the 13th digit of the catalog number to the number "2". (For example, a 35KA @480VAC, 40A, 3-pole, 100% rated 3VA61 is catalog number 3VA6140-5HL31-2AA0). Requires the use of rated lugs — see lug table below.
Click to expand...
 
wwhitney said:
Yes, if you have a 100% rated OCPD in its own enclosure supplying an MLO panelboard whose bus rating matches the OCPD rating, I believe that is all copacetic. If the panelboard bus is part of the feeder supplied by the 100% rated OCPD, then per the exception it does not need a 125% rating.


That is what I've always heard, but looking at that picture of a true panelboard from the other thread, the enclosure seemed so large that it wouldn't actually be a problem to provide the necessary air space around the 100% rated breaker, or even to provide a barrier that divides the enclosure into two compartments, with the 100% rated main breaker in its own compartment of sufficient size. So I'm wondering if either of those is a possibility.

Cheers, Wayne
Click to expand...
I looked through the siemens breaker catalog, and saw information about certain lugs being required and that the wire be 90 degree rated but sized at 75 degree, but could not find anything dictating they be in a separate enclosure or enclosure size. I found this document by Eaton (http://www.eaton.pl/ecm/groups/public/@pub/@electrical/documents/content/ap01200008e.pdf) , which states:

UL 489 9.1.4.4 A circuit breaker, having a frame size of 250A or greater, or a multi-pole type of any ampere rating rated over 250V; and intended for continuous operation at 100% of rating, shall be marked: Suitable for continuous operation at 100% of rating only if used in a circuit breaker enclosure Type (Cat. No.) ____ or in a cubicle space ___ by ___ by ___ mm (inches). Equivalent wording shall be permitted. The blanks are to be filled in with the minimum dimensions.
Click to expand...
 
electrofelon said:
Siemens new 3VA series offers a 150A frame that goes down to 40A:
Click to expand...
So approximately what does a Siemens 3VA61105HL262AA0 go for? That's 2 pole, 100A, 100% rated; or change to HL3 if they are only made in 3 pole, or change HL to a different trip unit if that's cheaper.

Along with the enclosure 3VAE250N3R? Which is almost 32" x 10" x 6", as the 250A frame size use the same enclosure.

Cheers, Wayne
 
I would bet that the Meter base part is rated 200 amps continuous just like all 200 amp meter bases that I have seen.

As others have said there is no way that the breaker section is rated 200 amp continuous....
 
Status
Not open for further replies.
Top