I am finishing my basement, and am in the process of doing electrical.
I did a load calc and came up with 181A, but my main panel is 150A.
So I need to upgrade to a 200A main panel. When I asked an
electrician about it he implied it was a really big deal, and the
"whole house needed to be brought up to code". I don't know what he
means by that? The meter is CL200 which I believe means it is rated
for 200A service so it looks like you just need to change the panel.
What am I missing?
I know that if the buried service cables were sized only for 150A then
I am in trouble and am looking at some big bucks to change, but as I
said the meter appears to be 200A rated. Could the utility have
installed cables for 150A anyway? That seems incredibly dangerous if
they did since someone might assume the system could handle 200A!
I would first check the load calculation, or have it professionally done.
The meter box can be rated for 200 amp with 150 amp wire feeding it, in
fact, I haven't seen a 150 amp meter box in years. The size of the
underground wire depends on who owns it. In some locations the utility
company owns it and they determine, depending upon the calculated load, if
it's of sufficient size. If you own it, you need minimum 4/0 aluminum or 2/0
copper for 200 amps. You also have to change the conductors from the meter
to the service panel, and upgrade the system grounding conductors. I've
never heard of a requirement to upgrade the internal wiring, just to
increase the service
Did you do your load calculation according to Article 220? If you figured
181 continuous amps than a 200 amp service will not be adequate. The main
breaker is only rated for 80% continuous load (3 hours or more) which is 160
In New Jersey one of the power company's has all of their residential
service feeders rated for a maximum of 310 amps. They don't want to be
bothered every time someone upgrades a service. The electrical contractor
does the connection at the house. Check to see if your power company has
info on a website.
Exactly how did you determine that you have a load of 181 amps. I hope you
didn't just add up all the amp ratings of your breakers. I only have a 100
amp service, yet I manage to run a whole house with electric cook top,
double electric ovens, all the other electrical equipment, an office with 4
computers with a large UPS to supply them, air conditioning, a full
woodworking workshop, etc. etc. and I have never had problems with capacity.
Double check your figures, remember it is so rare to have "everything"
running simultaneously, that it never really happens to most people.
I think about that (about not using all loads at the same time) when I
consider the electrical load of all my holiday lights. Some people
might think I need upgraded service, but all those lights use less
than the central A/C, which is not on at that time.
What the f**k could you be running to use 181A in a home?
And of course that would mean the everything is running at the same
time, which I highly doubt. I run a whole farm on 200A service and
never even come close to using 100A. Actually this farm was wired for
400A, but this was a full fledged farm with grain dryers and all of
that. I only use one of the 200A pull out cartridge fuse holders.
I'd hate to pay your electric bill either way......
If you truly need 181A, you'd be popping the breaker now and again. How
often does that happen? That is a very large load so you must have a huge
house with electric heat. Very few homes have that type of load.
If you truly have a 181 A load, you need a larger factor than 200A provides.
Keep in mind, the labor to upgrade is pretty much the same if you go to 200
whats the largest main panel available today. I asked awhile ago and
was told its 200 amps. Vistyed my wifes bosses home and noted it has a
PAIR of 200 amp main panels. Its like a mansion......
I am looking to upgrade and would go 300 amps if I could.......
I didn't say I was using the load NOW. I said I am finishing my basement, which
means I am calculating the load AFTER everything is installed. With the
addition of a heat pump, you have to add in compressor, air handler, AND the
heating element, which is really what pushed it over the 150A mark. I might
have been able to get by if it weren't for that.
I sort of question the load myself, I had my electrician in the other
day to plan a subpanel for my shop, he did a load check & I was pulling
60 amps,(30 on each leg). that was on a 103 degree day with all 3 air
conditioners running, 2 full size double door refrigerators, 2 small
refrigerators, a chest freezer & several other loads like the
ventilators for the green house, the attic power vent. I'm running a
small farm with a private well with a booster pump and a remote shop, a
2800 sq ft house all on a single 200 amp box.
The eletrician who want to redo all the wiring in the house is not the
elctrician you want to hire.
Why t call your local electrical inspectors, make an office appointment, and
actually find out what code in your area requires. Makes a lot more sense
than asking these locality dependent questions here.
It seems that most people are missing the point.
First of all, to the people who question how I have that kind of electrical
When the basement is complete I will have a three story home with approx 3000 sq
ft, and at least six bedrooms. A home theater, and a photography studio, plus
woodworking equipment in the garage - table saw, drill press, planer, band saw
etc. For heating/cooling I have three a/c compressors, including a heat pump
with a 5kw heating element. Double ovens in the kitchen. One large fridge,
large freezer, plus two small fridges. Attic ventilator, dishwasher, electric
clothes dryer. These things add up. And the shop equipment wasn't even
factored in, because I only use those one at a time on a 20A circuit (no 220v
equipment). Nor am I factoring in the home office with several PCs on all the
time, with a floor standing 8000BTU A/C unit to keep the room cool.
My current system would handle everything fine, but the addition of the basement
changes everything. I really don't understand why they didn't put a 200A in to
Secondly, to the people who say that I will never have that kind of demand at
I freaking know that. That's not the point. The point is, will it pass
inspection? What am I going to do if the inspector looks at the size of my home
and all the breakers crammed into the box, asks for a load calc, and I say "well
it's over 150A but hey I doubt I'll use it all the time"? The worksheet that I
used came from a book based on the 2005 NEC, and the formulas take into
consideration the fact that you aren't pulling the entire load all the time.
The final figure is a minimum, which means my box has to handle it.
As it turns out, I did make one error by not reducing the load from my double
ovens to 65%, which changed my total load to 171A. Still higher than 150A but I
get a bit more room.
Lastly, I want capacity for future renovations, like a screened in deck. And
the extra panel size will avoid a subpanel, which is a good thing because the
room with the breaker boxes will be my future office.
What brand 150A panel do you have? Can you install the same brand and
same series 200A panel, and swap in the 150A main from your old panel?
(Set the 200A main breaker aside for later.) That would give you 40
spaces in your new panel, lots of wire-bending room, and you could put
off upgrading the service conductors until later -- perhaps delay it
When you ran the calculations, did you factor in the heat pump's heating
strips and the compressor at the same time? I'm not sure, but I don't
think they ever operate at the same time.
Your electrician is the expert. You are dabbling. Let your
electrician size the panel as he will be the one responsible for it
passing inspection. There is no reason for you to even speak to the
Your call, but I prefer subpanels. They don't take up an appreciable
amount of space and they make it easier to do work without shutting
down the house.
THIS IS JUST GUESSING. I'm not there to actually look at your setup.
It sounds like you have everything other than a pannel with a 200 amp
disconnect. 200amp SE, and 200amp Meter base. Now all you need it a
One big question, are you tripping the current main disconnect? I
figure a service calc is an 'esitmate', for planning. So if you
aren't tripping anything, you should be ok till you can verify your
tom @ www.NoCostAds.com
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