Check my load calc?

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 expensive.

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 decision.

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.

watts 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 Total 17400

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?

Thanks

Reply to
rusty cranbrook
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You're adding up your small appliance load in the kitchen. You're not adding any A/C?

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..

Reply to
HA HA Budys Here

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.

Bob

Reply to
zxcvbob

Do you have: Air conditioning? Garage door openers? Range hood? 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.

-- Mark Kent, WA

Reply to
Mark or Sue

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.

Reply to
rusty cranbrook

Hi Bob

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 th>

Reply to
rusty cranbrook

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.

Best regards, Bob

Reply to
zxcvbob

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 parties.

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! :-(
Reply to
HA HA Budys Here

Hi Mark

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.

gas, you need to see if there is any significant nameplate load).

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.

Thanks everyone!

Reply to
rusty cranbrook

Thanks, that is useful info to incorporate into my calculations. This newsgroup can be pretty handy.

Reply to
rusty cranbrook

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 sq.ft.

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.

Reply to
HA HA Budys Here

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