220.53 appliances fastened in place

[Leespark57]

When calculating a service for a single family dwelling you are allowed to apply a demand factor of 75% for 4 or more appliances fastened in place. Is this for 4 different types appliances? Example, DW, disposal, over the stove microwave and a trash compactor.

Would a car charger fall into this category? Steam generator? An electric hot water heater? Attic exhaust fan? Electric can opener? Seems like this could allow a substantial reduction in service size, let's say if someone had a 100 amp car charger, simply by adding a small fixed appliance, can opener? Is this accurate??

Thanks

 

[kwired]

When calculating a service for a single family dwelling you are allowed to apply a demand factor of 75% for 4 or more appliances fastened in place. Is this for 4 different types appliances? Example, DW, disposal, over the stove microwave and a trash compactor.

Would a car charger fall into this category? Steam generator? An electric hot water heater? Attic exhaust fan? Electric can opener? Seems like this could allow a substantial reduction in service size, let's say if someone had a 100 amp car charger, simply by adding a small fixed appliance, can opener? Is this accurate??

Thanks

right in 220.53 it excludes "electric ranges, clothes dryers, space-heating equipment, or air-conditioning equipment"

Something like an attic exhaust fan is a fairly continuous load on summer days, but I don't see it would be excluded from this section either. They usually are pretty small load in comparison to heating or cooling loads as well though.

Can opener, you have one that is a fixed appliance? That is something that is typically plugged into a SABC which is already assigned a load of 1500 VA anyway.

You are more likely to run a separate circuit to a specific location on countertop for say a microwave (that sits on the counter). But technically this is another SABC and is 1500 VA for your load calculations.

Run a separate SABC to a dedicated outlet for a counter top can opener, and you need to assign it 1500 VA - must be a big can opener

I think other than the things mentioned, they are betting there isn't too great of a chance of having them all loaded at same time, or at least not for very long if they do. You still may have unique situation here or there where it may be good design practice to consider some things loaded at same time.

 

[lordofthisworld]

When calculating a service for a single family dwelling you are allowed to apply a demand factor of 75% for 4 or more appliances fastened in place. Is this for 4 different types appliances? Example, DW, disposal, over the stove microwave and a trash compactor.

Would a car charger fall into this category? Steam generator? An electric hot water heater? Attic exhaust fan? Electric can opener? Seems like this could allow a substantial reduction in service size, let's say if someone had a 100 amp car charger, simply by adding a small fixed appliance, can opener? Is this accurate??

Thanks

Can opener?

 

[Leespark57]

Sorry, not trying to be a wiseguy. Just questioning being able to apply a 75% demand factor on something like a high amperage EV charger, simply by having 3 additional appliances fastened in place, no matter how small. I imagine in the not too distant future EV chargers may be an average dwelling's largest load by far.

 

[kwired]

Sorry, not trying to be a wiseguy. Just questioning being able to apply a 75% demand factor on something like a high amperage EV charger, simply by having 3 additional appliances fastened in place, no matter how small. I imagine in the not too distant future EV chargers may be an average dwelling's largest load by far.

This only applies to dwellings, where load diversity generally isn't all that high other than for select items this doesn't apply to such as HVAC. Ranges and dryers have their own demand tables. It is only allowing 25% reduction for the load calculation. When/if EV's become even bigger thing, we could see changes. Or the charging equipment could even become "smarter" and limit demand at times when necessary

 

[tortuga]

I would guess an EV charger will run at night, or could be programmed to or monitor the mains via a smart meter and only run at max when likelihood of other residential loads is nill, and thus would qualify for a table like ranges and dryers and probably allow much larger EV chargers.