# Does panel have room for hot tub?



## Mcsparkin (Sep 12, 2012)

What is the best practice to calculate whether or not the current panel has enough room to add a 50amp load(for example)? 

I've been looking at demand factors section in the CEC but I feel like there must be a different way than calculating by sq ft/major appliances etc...Thank you for your time.


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## 480sparky (Sep 20, 2007)

Where on earth did you hear about 'adding up the breakers x .8'? The kid at Home Depot?

A load calculation is in order.

And what is a 'fat' 50a load?


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## chicken steve (Mar 22, 2011)

480sparky said:


> And what is a 'fat' 50a load?


It's trying to fit in 40a pants.....?

~CS~


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## acebradley (Mar 1, 2012)

Nec 220.83


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## btharmy (Jan 17, 2009)

480sparky said:


> Where on earth did you hear about 'adding up the breakers x .8'? The kid at Home Depot?


I had a customer call me to upgrade their panel because the existing service was WAY too small. I show up to have the customer add up the amperage of all of the breakers in their 100a 12 cir panel and tell me he needs a 400a service.  I can't imagine what some of the scumbag franchise contractors would have done in such a situation. I simply explained load calculations in simple terms and he was very relieved. I did get a 200a upgrade out of the deal (his wife wants a hot tub). And a customer for life I think.


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## aftershockews (Dec 22, 2012)

Mcsparkin said:


> What is the best practice to calculate whether or not the current panel has enough room to add a 50amp load(for example)?
> 
> I've been looking at demand factors section in the CEC but I feel like there must be a different way than calculating by sq ft/major appliances etc...Thank you for your time.


Here in Shelby County, it is defined in their book that:
The first 6 110/v circuit are calculated at 10 amps each.
Then next 6 at 5 amps each
Any remaining at 3.5 amps each.
Total is divided by number of phases.
All 220/v circuits are at nameplate value.







For instance:

A house has:
20 110/v circuits
1 stove
1 dryer
1 CAC unit at 20.3 MCA
1 WH


6*10 = 60
6*5 = 30
8*3.5 = 28
110/v = 118 amps / phases
single phase would be 59 amps
Stove = 40 amps 
Dryer = 20
WH = 20
CAC 20.3
159.3 amps total load.

This is just an example. It is not how the NEC tells us, it is how my AHJ tells us.


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## Mshea (Jan 17, 2011)

Not a cec load calculation.
The only way to do a house load calculation is by using 8-200.
Perhaps some day when the data from smart meters include 12 month demands that we might use that to add load like we can for a commercial service.
for the NEC users
5000 watts for the first 90 square meters (about 1000 sq feet) 1000 watts for the next 90 square meters and on and on
6000 watts for a domestic range or cook top and oven for stoves up to 12 KW. Add %40 for range over 12 KW.
%25 of the appliances over 1500 watts if a rnge is allowed for
1250 watts for a 5000 watt dryer.
750 watts for a hot water tank rated at 3000 watts
Central units are at the rating so a 20 KW furnace would add 20 KW.
Baseboard heaters are calculated at %100 for the first 10,000 watts and %75 of the heating over 10 Kw
Car outlets at 2400 watts if a 20 amp outlet or %100 for level 2 chargers.
Swimming pool and hot tubs are %100 of their rating.

Add the loads up and divide by the supply voltage (usually 240 volts) and done.


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