Hi all.. I'm trying to check some math here. I have a 150 amp service that I am moving and adding some circuits to. We added about 1200 sqft of house and I want to make sure the service will support it. Here is what I plan on installing in the panel. I may end up combining some of the rooms into one home run so I can leave a few spaces in the panel for future needs:

Master and 2nd bedroom --1 AFCI
Master, half, and full bath--1 20 amp GFCI protected
Hall lights and outlets, kitchen lights, sunroom lights and outlets, 1 20 amp
Living room, dining room, exterior lights and interior outlets 1 20 amp
3rd bedroom and office --1 AFCI
Laundry lights, 120v outlets, pantry light and outlet, hall lights and outlets 1 20 amp
Dryer-1 40 amp
Tankless water heater -1 60 amp
Gym lights and outlets 1 20 amp.
Wetbar outlets, outside outlets, 1 20 amp GFCI protected
Kitchen--fridge 1 20 amp, microwave 1 20 amp, counter top and island outlets 1 20 amp GFCI protected.. Dishwasher, disposal and trash compactor 1 20 amp.
AC--unsure, but I am going to assume a 60 amp for the system? It will be a 5 ton handler and compressor.


OK.. I'm updating some info here:

The house has 3200 SQFT living area. Living, dining, kitchen, 2.5 baths, 3 bedrooms, pantry, laundry room, sun room, gym, and office.

Each room has the following: (all lights are 4 inch cans unless otherwise specified and all fans are without lights):

Gym 400sqft, has 6 lights, 1 fan and 9 receptacles. Will have a dry sauna 110v.
Sunroom 200sqft has 4 lights, 1 fan 6 outlets and a wetbar that requires a GFCI.
Pantry 20sqft 1 light , 1 outlet
Hall 2 lights 2 outlets (hall is 12 feet long, 6 feet wide)
Laundry 60sqft 2 lights, 2 outlets (1 washer, 1 other), Dryer, Tankless water heater Titan N120.
Office 200sqft 4 lights, 5 outlets
Living Room 250sqft 4 lights, 1 fan, 7 outlets
Dining room 120sqft 2 lights, 1 fan 3 outlets
Half bath 40sqft 2 lights, 1 ventillator fan, 1 GFCI
Full bath 70sqft 4 lights, 1 ventillator fan, 1 GFCI, 1 Jacuzzi tub
2nd Hall 2 lights, 2 outlets (hall is 12 ft long, 4 feet wide)
Master bed 260sqft including closet 8 lights, 10 outlets
Master bath 120sqft 4 lights, 1 ventillator, 1 GFCI at sink, and one outlet at vanity
3rd Bedroom 240 sqft 4 lights, 1 fan 6 outlets
2nd bedroom 160sqft 2 lights, 1 fan, 4 outlets
Kitchen 4 lights, Stove with cooktop, Fridge, microwave, dishwasher, trash compactor, disposal. Need GFCI for counter top and GFCI for Island. Island contains dishwasher, trash compactor, and disposal.

Additional info: There will be a 5 ton compressor and air handler unit installed. We don't have it yet, so I don't have the dataplate info for it. That is true of all appliances at this point, so I will have to assume the "typical" usage for these items.

OK.. please don't add up my SQFT, I am estimating each room, but the total is a little under 3200sqft living area.

1. I will combine lighting and outlets in a few rooms to maximize use of breakers. I know that I need to be around 1980 watts total.
Q: How much wattage do you apply to an outlet when usage is unknown? Lights are easy, I will assume 100w per light, but reality will probably be 60 per light. Is there a maximum number of devices allowed per branch? I can't find anything in the NEC.

2. Q: I believe the NEC allows combining more than one bathroom GFCI on the same breaker. Am I reading that correctly? If so, I will use one homerun for all 3 bathroom GFCIs. They are close enough to make it work.

3. I also thought I read that I need a dedicated line for dishwasher, disposal and trash compactor... is that right? If so, ouch! I was going to put them on the same circuit.

4. In the kitchen, I was going to have a dedicated circuit for the fridge, microwave, stove of course, and run a separate circuit for the counter GFCI and Island GFCI. Q: can I combine the counter and island GFCIs on the same circuit? 4 outlets total.. or do I need the minimum 2 separate circuits I read about?

5. Also in the kitchen, the island is just that, it is out in the middle by itself on a slab. I plan on breaking the slab in running the wires to the island through the slab. Should I use metal or plastic conduit for this? Does it matter?

The main panel next to the meter will serve only as a main breaker providing service to the sub panel which I plan on putting in the laundry room on the wall that shares studs with the 3rd bedroom. The only exception to this may be that I run the AC compressor and handler breakers to the main panel outside to free up some space in the interior panel. It's an older couple and I don't want them to have to go outside to reset a breaker if I can help it. I will use a 150 AMP breaker on the main to "cover" the 150 amp sub panel.

And so the big question is... will the current 150 amp service be sufficient for their adapted needs?

Thanks.. Jerry

Need to know the total square footage of livable space.

60 Amp for water heater? Must be one of those tankless units?

Need to know nameplate data from HVAC unit. 60 Amp breaker does not tell me the actual load. If I use 60 amps, it will skew the numbers, with a cushion.

I updated my original question.. 3200sqft of living space. Yes, a Titan N120 tankless water heater. I don't have the AC unit yet, but it will be a 5 ton compressor with air handler. My original math came up to a 175 amp service needed.. I hope I'm wrong. Of course the city service wire is buried and I have not even located the transformer yet.. could be really far away. :( The major appliances are the tankless heater, 5 ton AC system, dryer, oven with cooktop, washer, fridge, microwave, dishwasher, trash compactor, garbage disposal, and a 110v sauna that produces dry heat... I don't have this yet either. The couple are supposed to be getting it soon. Most of these seem to require a 20 amp breaker and use 1500watts. Everything else is pretty standard... lights, fans, 110v outlets, etc.. Thank you.

After doing the service rating calcs, I arrive at a connected load of 141.83 amps, using 11.8 KW for the water heater, 8 KW for a range, and 12 KW for the HVAC.

Quick answer is you can get away with a 150 Amp service, I highly recommend you install a minumim of a 200 Amp service, for several reasons.

I will have more time later to address all of your other questions.

Thanks. I found the answer in the NEC for the kitchen appliances. Each has to have it's own circuit.. bummer. Also found that I can combine GFCIs on same circuit for the baths, but the kitchen requires 2 separate "outlet" circuits. So I'll do one for the counter GFCIs and one for the ISland GFCIs. The owner decided to go with a 50 gal electric water heater so that will spare some amps.. Thanks.

Jerry,

When you say, "I found the answer in the NEC." I have to ask what answer you found and are you sure you have interpreted correctly?

Exactly how do you plan on combining GFCI receptacles in the bathrooms?

Here are some guidelines. If you bring a single 20 amp supply into a bathroom, it can service the other equipment in the same bathroom. It is never wise to put lights on the same circuit as a GFCI protected breaker. If the breaker trips, out go the lights and there you stand.

If you choose to serve two bathrooms with the same 20 amp GFCI protected circuit, then you cannot connect anything else to this circuit.

From a user perspective, if you have two women in the same house and both wash and dry there hair at approximately the same time, the circuit will probably trip and you will two very upset ladies on your hands.

Personqally I believe it is best to supply each bathroom with its own 20 amp receptacle circuit.