I have a 100 amp service, #4 copper wire supplies it underground and
so I don't think I can put in a larger main breaker unless a new
service is installed. I would like to check the probably future load
on the service to help aid in deciding about putting in a new service,
which would involve going across the street and would be quite
I'm trying to calc using an book I have on wiring. This is just for my
own thinking; a real electrician would be involved in the final
The home is a 2500 SF house in CA. All of the major electrical
appliances will be gas. Half of the home has been remodelled to code
and the other half will be.
Home SF 2500 sf x 3 7500
Kitchen 4 x 1500 6000
Dishwasher 1 x 1500 1500
Disposal 1 x 900 900
Laundry 1 x 1500 1500
First 10000 10000
40% of balance 2960
Load calc subtotal 12960
Furnace 1 x 1800 1800
Load in watts 14760
Load in amps 61.5
Anything that is obviously wrong with this calc?
You're adding up your small appliance load in the kitchen. You're not adding
Also - pulling new feeders under a street isn't as difficult as you might
imagine. Big truck, hydraulic winch, 3 existing #4 conductors yanks out, and
the new in, fairly easily - the street typically is not dug up.
Also - are you sure your feeders come across the street at all? That's highly
unusual, at least around here..
Thanks for responding. Where I live we don't need A/C (and the book I
have said to add a single load value for furnace and a/c as they
aren't used at the same time).
I wasn't sure what you meant by "You're adding up your small appliance
load in the kitchen." Are you saying that I'm overdoing it? "The Book"
said the min is two circuits; this kitchen will be large so I
projected 4. But, I sure have no idea what makes sense, suggest away.
That is very interesting about pulling new wires. It would be cool to
get a larger service, it would have to be a plus. I'll check it out.
Yes the juice comes from across the street; was done in 1952.
firstname.lastname@example.org (HA HA Budys Here) wrote in message
You're supposed to add the load of the permanently connected appliances -
that's like, Heat/Vent/Light units in bathrooms, auxiliary water heaters,
dishwashers. The kitchen load pretty much remains the same once the basics are
factored in, no matter how many additional kitchen circuits you've added beyond
the minimum your kitchen calls for.
Think of it like this - I added 2 double duplex outlets and 4 circuits to my
own kitchen which already had 2 small appliance circuits covering the basics,
and 3 circuits covering additional, permanently connected appliance loads.
The new outlets/circuits are used 2x a year for a buffet spread when I host
The original 2 code required countertop small appliance receptacles, fridge,
coffeepot, toaster, etc, and 3 circuits for the microwave, dishwasher, and
insta-hot water tap account for 99% of my kitchen load. The additional
double-duplex circuits don't need to be factored into my home's load calc.
What would be cooler than a larger service, is not paying for one if it's
completely unnecessary, and spending that money instead on a nice, 52" plasma
television, or an outdoor jacuzzi tub! But if you go that route, then you
*would* need a bigger service! :-(
What size conduit is the existing service in (assuming they used conduit)?
If it is at least 1 1/4", you can run 150A service by just pulling new
wires in the existing conduit. IIRC, 150A service can be supplied with two
#2 hot wires and a #3 grounded neutral, and it just barely legally fits in
a 1 1/4" conduit if you use compact conductors like THWN.
The iron pipe is I.D. 1 3/8 if I remember; I'm not sure if that makes
it nominal 1 1/4" or 1 1/2". But pulling some bigger wires - I hadn't
thought it possible but you've opened my eyes. I'd like to have more
than 100 if can get it. Thanks for suggesting.
Otherwise, do you think the load calc I ran is reasonable?
I think 4 kitchen circuits (not including the dishwasher and disposal) is
ridiculous, but it more than makes up for anything else you forgot.
I ran a load analysis on my house when I bought it, and I came up with
about 65A *including* an electric clothes dryer. If your house is all gas,
your existing 100A service is probably plenty.
Do you have:
Garage door openers?
Ceiling fans (may be able to count just the motor portion)?
Hot tub or jetted tub?
Why do you have 4 kitchen circuits? Do you have two kitchens?
What is the electrical load of the water heater and range (even though they're
gas, you need to see
if there is any significant nameplate load).
Your furnace load seems high for just a fan blower motor.
I do have a garage door opener; and will have a range hood.
I just doubled what the book said was the min; figured a large kitchen
would need it. But I guess I'm wrong.
WH has no wiring at all. Range is unknown, but I'll add something for
the future purchase.
OK, thanks, I didn't check it, I just took a stab.
All in all it appears that the number I ended up with is not too far
off. After adjusting, surprisingly 100 amps seems to be enough. But I
still like the idea of getting it up to 150, as some have suggested
the pipe might sustain.
Garage door opener - no need to include it's considered a convenience device,
not a permanently connected load, despite the presense sometimes of a dedicated
outlet or even circuit for it.
A GDO operates for what, 10 seconds 4 times a day?
Range hood? Permamently connected fixture but again, it's typically part of the
already included kitchen convenience circuit, or regular convenience/lighting
circuit. IOW it's already factored in / accounted for in your 3 watts per
Gas range outlet can not only be on a local convenience ckt - it's total load
is typically a 40watt appliance bulb and a spark ignitor if inconsequential
wattage. It's also already factored into the 3 watt per sq. ft. calculation no
need to "add" it again.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.