100 amp to 200 amp Service Upgrade w/Underground wires

[IT Guy]

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

200 wiring?

Thanks...

[IT Guy]

Clarification: $1500 for service upgrade and $2000 more if they have to dig/replace the service wire.

[Joseph Meehan]

What he says is all reasonable. 100 amps today is rather skimpy. There is no way to know about the cost until the electric company responds.

[skeezics]

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 for sure.

skeez

[RBM]

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

[deviL doG]

The need to use larger wire results from the heat created by the larger 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 box.

[Speedy Jim]

Would you please post the service calculations he used to justify this expense for adding 2 pumps drawing a few Amps each?

Jim

[FDR]

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.

[hallerb]

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 upgrade.

i bet the panel is maxed out.

could install a sub panel to fix that.

[ng_reader]

That's pretty much *it*, isn't it?

OP may need to replace the 4/0 with 2/0. The only way to do so, is to dig it up.

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.

'just wondering...

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.

[SQLit]

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 years.

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 the electricitic service.

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.

[hallerb]

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.

[IT Guy]

I posted the original message ... Thanks to everyone for the great responses ..

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 each evening.

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.

[Calvin Henry-Cotnam]

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 240.

[antonr01]

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.

[Jim Redelfs]

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 no-dig.

[Chris Lewis]

According to IT Guy :

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.