Residential Load Calculations for Art Studio, Workshop, Hot Tub, and Space Heater

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paulgarett

Member
Location
San Rafael, CA
Some interesting load calculation questions. Thanks for your help.
Paul.

1. How should motors for a residential workshop, be included in the main service load calculations?

2. How should the 1500 VA small-appliance load, be included for a workshop and an art studio? The workshop and the art studio both have bathrooms and a sink counter area.

3. How should a 240 Volt, 50 amp hot tub be included in the main service load calculations?

4. The largest load of an A/C or a heater is included, the smaller omitted. Would a hot-tub be a part of this rule?

5. How should a portable, yet somewhat permanent, space-heater load be included in the main service load calculations?

6. If the space heater is the only means of heating the art studio, would it be included as a small appliance, the heating load, or the general lighting load.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
Some interesting load calculation questions. Thanks for your help.
Paul.

1. How should motors for a residential workshop, be included in the main service load calculations?

2. How should the 1500 VA small-appliance load, be included for a workshop and an art studio? The workshop and the art studio both have bathrooms and a sink counter area.



3. How should a 240 Volt, 50 amp hot tub be included in the main service load calculations?

4. The largest load of an A/C or a heater is included, the smaller omitted. Would a hot-tub be a part of this rule?

5. How should a portable, yet somewhat permanent, space-heater load be included in the main service load calculations?

6. If the space heater is the only means of heating the art studio, would it be included as a small appliance, the heating load, or the general lighting load.

Is this something you are working on? Or are these questions from a text book.
I or someone may can help more if we know what these questions pertain to. #2 has nothing to do with a kitchen and SABC.
 

broadgage

Senior Member
Location
London, England
How large are the motors ?
If small and cord and plug connected, then it might be argued that no special allowance need be made. After all no makes any special allowance for vaccuum cleaners or powered hand tools.
Code permits of only allowing for the heating or the cooling load, whichever is greater. The assumption being that no reasonable person would use both at the same time. I dont believe that a hot tub could be considered under this rule, use of this appliance at the same time as the A/C is entirely reasonable and forseeable.

If no fixed heating equipment is provided in a space, then there is no way of determining what portable space heaters will later be used.
It would reasonable to make an allowance of so many watts per square foot, the allowance depending on climate.
 

Smart $

Esteemed Member
Location
Ohio
Hmmm... I think to answer your questions more thoroughly, we need to know the bigger picture here first. For example, you ask about SABC... but if the qualifying circuits are in a dwelling on the same property, there is no need to add more in another structure or addition to the dwelling.

Motors are calculated the same regardless of what type of occupancy is involved. Also, you do not double up a motor load if involved in heating and cooling applications, or add as a motor load when omitted under HVAC.

The hot tub is figured in at 12,000VA continuous, I believe... better answered by others (read: I don't have my reference handy and the online version #$&%'s)... but I am certain it is not included in the HVAC.
 

paulgarett

Member
Location
San Rafael, CA
Answering Your Questions

Answering Your Questions

To answer your grateful questions, the load calculation questions refer to a customers property. The customer currently has a 650 sq. ft. detached art studio and a 850 sq. ft detached work shop. Both buildings do not have a power supply. The customer will demo a major portion of their home for a major re-model and add-on. At that point, trenches will be dug to the art studio and workshop to provide power. The house will be about 2500 square feet, omitting the garage and porch.
Thank you
 

Smart $

Esteemed Member
Location
Ohio
To answer your grateful questions, the load calculation questions refer to a customers property. The customer currently has a 650 sq. ft. detached art studio and a 850 sq. ft detached work shop. Both buildings do not have a power supply. The customer will demo a major portion of their home for a major re-model and add-on. At that point, trenches will be dug to the art studio and workshop to provide power. The house will be about 2500 square feet, omitting the garage and porch.
Thank you
These buildings of note are not dwelling units. The workshop and studio are what is called, in the 2011 NEC, accessory buildings having electric power, under 210.52(G)... requiring only one receptacle outlet calculated at 180VA per building, in addition to outlets for specific equipment.

As to the portable heater (assuming plug-and-cord-connected), you can call it specific equipment or use the required receptacle outlet to power it. Powering these buildings, the design is very flexible.
 
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