424.3 is only regarding branch circuit sizing and says nothing about feeder or service sizing.What about 215.2
220.3 indicates 424.3 is "special", but 125% factoring for continuous load(s) is not implemented under Article 220.
424.3 is only regarding branch circuit sizing and says nothing about feeder or service sizing.What about 215.2
424.3 is only regarding branch circuit sizing and says nothing about feeder or service sizing.
220.3 indicates 424.3 is "special", but 125% factoring for continuous load(s) is not implemented under Article 220.
Are we not talking about a feeders here-- I am not sure why 424.3 has anything to do what Gus has mentioned. I am still uncertain why 215.2 is ignored by you. Are you saying it doesn't say what I think it says or are you saying that we ignore it? :?
Yep.. there seems to be a contradiction there.One of the things that bothers me is the seeming conflict between 215.2 and 220.51.
I am not ignoring it. I'm simply discussing the root of the misunderstanding. 215.2 says you have to size at 125% continuous load. 424.3 says the heaters must be considered continuous AND only for sizing the branch circuits. Nothing says the heater load(s) shall be considered continuous for feeder and service sizing. Now if it outright said heater load(s) shall be considered continuous, without mention of branch circuit sizing, then I would think that would carry up through feeder and service sizing... but it does not say that!!!Are we not talking about a feeders here-- I am not sure why 424.3 has anything to do what Gus has mentioned. I am still uncertain why 215.2 is ignored by you. Are you saying it doesn't say what I think it says or are you saying that we ignore it? :?
One of the things that bothers me is the seeming conflict between 215.2 and 220.51.
There is no contradiction between the two. 215.2 says nothing about fixed space heating specifically. You guys are extracting an interpretation based on how you read 424.3. As mentioned throughout, 424.3 says nothing about feeder and service sizing. 220.51 further substantiates my viewpoint.Yep.. there seems to be a contradiction there.
There is no contradiction between the two. 215.2 says nothing about fixed space heating specifically. You guys are extracting an interpretation based on how you read 424.3. As mentioned throughout, 424.3 says nothing about feeder and service sizing. 220.51 further substantiates my viewpoint.
PS: See post#4... 220.51 prevents a feeder being lesser rated than a branch circuit.
220.51 states heater load is calculated at 100%. It is saying there is no demand factor for heating. It has nothing to do with whether the heater load is continuous or noncontinuous.Sure art. 215.2 takes us to T.220.3 indirectly but it means nothing in my opinion if that has nothing to do with feeders. Why is it even brought into this discussion?
So art. 215.2 takes us to Parts III, IV, and V of art 220 where we find 220.51 which states fixed electric heat to be calculated at 100%. So then what does the last part of 215.2 mean if it is to be ignored for heaters and possibly other piece of equipment.
I don't understand how we extract from 424.3 when in fact I am ignoring it as I don't see what part a branch circuit plays in this discussion. Please enlighten me as you are seeing something I am not.
In the case where a thermostat malfunctions, turning it into a continuous load.220.51 states heater load is calculated at 100%. It is saying there is no demand factor for heating. It has nothing to do with whether the heater load is continuous or noncontinuous.
I have a question for you: Do you know of any typical fixed space heating systems which are designed and installed to be continuous loads? In my mind, they are all designed to be thermostatically controlled and thus noncontinuous loads.
I have a question for you: Do you know of any typical fixed space heating systems which are designed and installed to be continuous loads? In my mind, they are all designed to be thermostatically controlled and thus noncontinuous loads.
All I'm saying is where a noncontinuous load is required to be considered continuous for the purpose of branch circuit sizing there is nothing which says that consideration must carry through feeder and service sizing. I am not saying ignore it at the branch circuit level... as it is required.Well most water heaters are continuous because the NEC says so so why, when 424.3(B) that states branch cir. sizing must be for continuous load, should we ignore it.
It also makes no sense that a branch circuit would be required to be 125% but the feeder feeding all these continuous loads-- whether they are or are not consider that way in our minds- doesn't need to be continuous.
I have a question for you: Do you know of any typical fixed space heating systems which are designed and installed to be continuous loads? In my mind, they are all designed to be thermostatically controlled and thus noncontinuous loads.
Well I'd certainly like to get it straightened out... not just for your sake, but for others and myself as well.Smart I responded to this
My point is we install all heater to be continuous, baseboard heat as well as electric heating systems. I don't believe they generally run for 3 hours especially in new homes but the code still requires it.
I still don't see how you avoid 215.2 which is about feeders saying the minimum size must be sized to 100% of noncontinuous loads plus 125% of continuous loads. If we have all continuous loads then how do we avoid that-- I know you stated 220.51 says to calculate at 100%. This is where I believe a few of us may be confused. Maybe just me. IDK. This is where you keep saying there is nowhere in the code that requires the feeder to be 125% but you don't address it-- maybe if you explain that to me. I totally understand where you are coming from but this discrepancy has me but you say there is none.
I will add if the heaters are t-stat controlled it seems obvious the feeder would not need to be 125%. I don't even know why they are considered continuous at all even for the branch circuit. I am sure there are instances where a heater may be in a well house where there is little to no insulation and will run constantly so perhaps that is where it is coming from.
Please forgive me for dragging this out as I am sure you are tired of it..
(1) General. Feeder conductors shall have an ampacity not
less than required to supply the load as calculated in Parts
III, IV, and V of Article 220. The minimum feeder-circuit
conductor size, before the application of any adjustment or
correction factors, shall have an allowable ampacity not
less than the noncontinuous load plus 125 percent of the
continuous load.
Not contending that.Smart that what I keep saying 215.2-- we are not in calculations but in what is required for a feeder
Being considered continuous for branch circuit sizing involves 210.19(A)(1). How are these noncontinuous loads considered continuous under 215.2(A)(1)?If the branch circuit is continuous as required in 424 then does that 125% mentioned above state we must use it at 125%?
Being considered continuous for branch circuit sizing involves 210.19(A)(1). How are these noncontinuous loads considered continuous under 215.2(A)(1)?
220.1 Scope.
This article provides requirements for calculating branch-circuit, feeder, and service loads. Part I provides for general requirements for calculation methods. Part II provides calculation methods for branch-circuit loads. Parts III and IV provide calculation methods for feeders and services. Part V provides calculation methods for farms.
215.2 Minimum Rating and Size.
(A) Feeders Not More Than 600 Volts.
(1) General. Feeder conductors shall have an ampacity not less than required to supply the load as calculated in Parts III, IV, and V of Article 220. The minimum feeder-circuit conductor size, before the application of any adjustment or correction factors, shall have an allowable ampacity not less than the noncontinuous load plus 125 percent of the continuous load.