Electrical load calculation for a change of use facility (2020 NEC)

[fandi]

Hello All,
It's a change of use of an existing facility from a hotel to one-bedroom apartment (the bathroom is inside the bedroom).
Receptacles in different rooms were being shared the same circuits and now are being shared by (3) different units.
Same with bathroom circuits are now being shared by (2) different unit bathrooms.
I even see one existing circuit now feeds (2) different unit lights AND a common elevator light.

Traditional load calculations in 2020 NEC Article 220 don't apply because the units share same receptacle circuits and lighting circuits. If each unit is fed from an independent 20A circuit then the total load is less than 20A.
What change to be made to make this change of use NEC compliant?
Thank you.

 

[Xformer680]

IMHO... This sharing of circuits is not allowed. Each one bedroom apartment should have access to OCPD for the circuits in that apartment.

 

[fandi]

IMHO... This sharing of circuits is not allowed. Each one bedroom apartment should have access to OCPD for the circuits in that apartment.

Thanks. I think so too. Do you know a NEC code section for not sharing same circuit between different units?

 

[Xformer680]

Well, I learn something new every day. Looks Like 240.24(B) allows it under certain conditions.

 

[fandi]

Well, I learn something new every day. Looks Like 240.24(B) allows it under certain conditions.

Thanks a lot. The problem is how do we know a 20A circuit would not be overloaded if (3) units plug heavy loads on the same circuit at the same time?

Hello Mods, I realize I posted the question in the wrong sub-forum. Could you please move my thread to 'NEC' subforum?
Thank you so much.

 

[tortuga]

Traditional load calculations in 2020 NEC Article 220 don't apply because the units share same receptacle circuits and lighting circuits.

There is no exemption from the 3VA per sqft branch circuit load requirement if apartments are all on one common service. You'd calculate the square footage served by each branch circuit on the floor plans.
In a multi tenant residential occupancy a 15A branch circuit can serve 600 SQFT, and a 20A branch circuit can serve 800 SQFT.
You can have any number of outlets , walls or different occupants in that area as long as all occupants have access to the panel and the sqft is not exceeded.
Presumably any fixed HVAC loads like window AC, electric resistance heat are on individual circuits or you reduce the area served.

 

[fandi]

There is no exemption from the 3VA per sqft branch circuit load requirement if apartments are all on one common service. You'd calculate the square footage served by each branch circuit on the floor plans.
In a multi tenant residential occupancy a 15A branch circuit can serve 600 SQFT, and a 20A branch circuit can serve 800 SQFT.
You can have any number of outlets , walls or different occupants in that area as long as all occupants have access to the panel and the sqft is not exceeded.
Presumably any fixed HVAC loads like window AC, electric resistance heat are on individual circuits or you reduce the area served.

Can you tell me what's the code section in 2020 NEC talks about 'the square footage served by each branch circuit'?
I only see 220.12(J) talks about 3VA/sf for general loads but not for each branch circuit.
Also the problem is how do we know a 20A circuit would not be overloaded if (3) units plug heavy loads on the same circuit at the same time?
Thanks.

 

[tortuga]

210.19(A)(2), 210.20(A) and 210.11
And I I need to my earlier comment, 210.25 restricts branch circuits to one dwelling unit.

 

[fandi]

210.19(A)(2), 210.20(A) and 210.11
And I I need to my earlier comment, 210.25 restricts branch circuits to one dwelling unit.

Thank you. I guess this change of use won't work because of 210.25(A).

 

[tortuga]

Well I would not loose all hope a skilled residential electrician could probably split the circuits, they can still be all in one panel that the occupants have access to. And with AFCI/GFCI breakers its probably better to not have dwellings sharing circuits.

 

[fandi]

Well I would not loose all hope a skilled residential electrician could probably split the circuits, they can still be all in one panel that the occupants have access to. And with AFCI/GFCI breakers its probably better to not have dwellings sharing circuits.

Thank you so much.

 

[d0nut]

Make sure you understand how the owner intends to meter each tenant and how the tenants will be billed. This decision could have a significant impact on the electrical system design.