I have a 28 year old home, about 2000 Sq Ft, with 100 amp service. I've not
noticed any problems yet, as a result of this.
I'm going to be putting in an above ground pool, and had my friend, a
licensed electrician, come over to discuss the electrical work to be done.
It was his first time here (only lived here 1 yr), and upon going in the
basement his immediate reaction was that I need to upgrade from 100 to 200
amp service. We do have central air and my wife does alot of laundry, but
it hasn't been a problem yet. He said adding the pool pump/filter would be
too much for 100 amp. I trust this friend, and am not disputing the need
for this. But, when he realized that have underground wires he mentioned
that they may have to dig up the service wire to upgrade for 200. Mentioned
that they sometimes use bigger wire or have conduit that we could re-use w/o
digging, but I'm getting the feeling digging is going to be the result. He
said it'd be about $1500 for the upgrade, which I can deal with, but about
$2000 if they have to dig. He's calling the power company next week to
find out what's underground.
What is the liklihood of not having to dig? Do they really put down wire
bigger than necessary in case someone upgrades? Also, was it common 28
years ago to use conduit underground, and if so, conduit big enough for the
Agreed. Heck, 100 amps was skimpy when his house was built in 1978.
It is unlikely the buried service is fully in conduit. Some years ago, our
local power utility placed new buried drops in flexible conduit for a few
years but stopped due to the added cost. As I understand it, the flex conduit
silted-in anyway, making pulling-in replacement cable impossible.
Agreed. However, I'll bet they declare the existing, buried service suitable
for the upgrade.
If all they're adding are some pool pumps, they might consider a lesser
upgrade to 150 amps, particularly if that makes the difference between dig or
i had this done 3 years ago and this is how it went. my service is
overhead. the wire from the street did not get replaced. the wire from
the wheather head to the meter base and to the panel did get replaced
with larger wire. i suspect the underground wire you have is large
enough to support the upgrade. your hous is 28 yo mine is 32 yo so
same codes should have applied. but for sure only the power co can say
Each utility company does this differently, so you really need to get
answers from them. Some underground service cables are owned by the utility
company, so they will determine if the size needs to be increased due to the
larger service, and would probably be responsible for doing the work. Some
underground services are customer owned from the property line, which would
almost definitely require you to replace the conductors for larger ones
load. If the wire is too small the heat created could cause a fire. But only
if it were in contact with flammable materials, like inside or up against
your house. As long as the heating is not so excessive as to melt the wire
the increased voltage will be carried. If the wires are overhead they are
air cooled, so the electric company will always try and duck out of
replacing these unless you make a big stink. Underground presents a
different kind of problem, because the wire would not be air cooled and
might get hot enough to melt the insulation which, while not much of a fire
danger, would cut out your power quite spectacularly. So I can't imagine any
reputable parties recommending keeping the underground wires unless they
were sure that the size was large enough to handle the load without
exceeding the heat spec for the wire.
100 amp services were commonly done with 2/0 cable back then. 200 amp
usually requires 4/0 cable. The electric utility will be able to determine
the size of the existing wire on visual inspection as soon as they open the
OP may need to replace the 4/0 with 2/0. The only way to do so, is to dig
Same thing. I cheaped out, I think, when I replaced my breaker panel. Kept
100 amp service, jut put a panel in that had like 30 breakers.
Gas heat, dry, and cook, so I rationaled it that way.
But, now I that I read this thread, might think the only thing I need to do
to "upgrade" to 200 amp service is swap out the circuit breaker panel.
And - a side note - all that really thick cable is aluminum. Now-a-days. I
believe it used to be copper prior to (fill-in-the-date) but that became
cost prohibitive. So, copper inside the walls, but aluminum to the pole.
Yeah, I find it odd that a pool pump would push you to an upgrade. The
central air and (inferred) electric clothes dryer are big loads and if
there's been no problem with them, I can't see how an above ground pool pump
is going to blow the current situation. The only thing I could see is that
there's no breaker spots left for a dedicated line.
if the person has gas, then changing to gas dryer is a option. cuts
dramatically the electric load.
Upgrading is always a good idea and a sales feature at resale time. but
costs big bucks.
two pool pumps are a small load increase to require a 100 to 200 amp
i bet the panel is maxed out.
could install a sub panel to fix that.
> Would you please post the service calculations he used to
I posted the original message ... Thanks to everyone for the great
My friend (since childhood), who's been an electrical contractor for 25
years came to my newly purchases house for the first time to check out the
work required for the pool.
He said that panel is maxed out, with some doubling up already, and that I
could just add another panel to deal with that. But, he said he didn't like
the looks of my box, in that the wire coming in wasn't in a pipe and he
thinks water has likely been coming into the box. Regarding the load, I
have a very large new cental a/c tower, my wife does laundry (all elec)
around the clock, my house is about 2700 sq feet, lots of cooking on the
elec range, and my daughters use their curling irons/straighteners most of
He said I'm probably getting away with it now because I have a gas hot water
heater. He thinks I'm right on the border now, and perhaps the pool
pump/filter won't be the breaking point, but he thinks I need upgrading even
w/o the pool.
Given the description, he's probably exactly right. The pool pump will only
draw 5-10A (presuming you put in 240V pump).
As others have suggested, you need to get your utility to tell you what
ampacity is permissible on your existing underground feed. You'll probably
want to avoid the expense of redigging. If you can upgrade to 150A without
redigging, you'll want to seriously consider that instead of 200A.
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
What are the odds that your "friend" did a load calculation?
Call the power company with the meter number and find out the high
usage information. I do not know the meter type so I am using a broad terms.
Some meters will provide amazing amounts of information. Go back a couple of
Once you have the information then sit down and do load calculation on the
dwelling. An extra 5 horse power of pump may not take you over the "change
out line" If you have a gas service I will bet your big loads are not on
If you need help with the load calculation email me directly it is easy. If
your "friend" can not do it. I certainly would not spend that kind of
money when I did not have to.
If you dont need to replace the underground line, definetely upgrade!
there are services that can drill underground, and run the cable with a
minimum of digging. cost more but saves restoration hassles. worth
getting a price.
I would install the new line in conduit, it costs a bit more, but makes
replacement easy if ever needed again.
if your lucky the existing cable is in conduit.
Pool pumps are in the 1/2 to 3/4 horsepower range. (A 5 HP motor is getting
into the range where it has to be three phase!).
I know from experience that a typical 3/4 HP pool pump can be wired or
120 or 240 volt operation, and draws 10 amps on 120 volts or 5 amps on
"I really think Canada should get over to Iraq as quickly as possible"
Well, you could just put the pool in and see how it goes. You might
have to do some "load shedding" if you trip the main breaker. But do
it this way. Get the rating of your central A/C unit. Then look at
other major loads. Electric dryer, electric water heater, anything
like that. A 100 amp service is only good for about 80 amps continuous
on each leg. At 220 volts and 80 amps, your kw capacity is about 16
kw. If you balance your loads, it might still work without tripping
your main. The above ground pool filters are about 1 - 1.5hp and draw
maybe 10 amps on their own 120 volt circuit. Notice it is a 120 volt
circuit. 220 volt circuits draw the amps on both legs. Your central
air unit is 220 volts.
I realize I may be getting complicated, but write your major loads down
for summer and see what it adds up to. The information is in the spec
sheets for each item or usually is on a nameplate. I run my filter only
about 6 hrs a day, usually between 11:00 am and 5:00pm.
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