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Advice Needed: How many amps required?

Posted by ChrisInSD (My Page) on
Fri, May 23, 14 at 13:16

I know little to nothing about electrical matters, and need some advice.

We are doing a complete gut remodel of the 1960 3 Bed/2 Bath 1400 SF home we bought a year ago. House has gas Clothes Dryer, Water Heater and Furnace. Everything else is electric. House has (or will have) central air.

We are replacing a 100amp Zinsco obsolete electrical panel. I received several bids for the whole house project and it was discussed that upgrading service to 150 or 200 amps would be best. I hadn't yet agreed details with the selected GC.

I showed up to the job site last night to see they have already upgraded the panel and installed a 125amp Eaton panel.

I spoke with Electrician this morning and told him--hey, later I want to add exterior lighting, I want to add a spa, I don't just want what will get be my today--I've gotta plan for down the road. This s/b 200amps.

He disagreed with me saying it's overkill and we have tons of circuit bays and plenty of capacity for whatever we want to do in the future. I can't really argue with the guy because I don't know anything. All I know is everyone else told me 150-200 amps.

He also told me "it's not just 125 amps, you have 100 amps on both legs." I have no idea what that means.

Can anyone help me out here? Is this right? Should I insist on 200 amps?


Follow-Up Postings:

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RE: Advice Needed: How many amps required?

Good to get rid of the Zinsco.
It would be good to get rid of an electrician who really does not know what he is talking about-- if that is what he actually said.


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RE: Advice Needed: How many amps required?

The "electrician" (and I use the word loosely) thinks that with a 125A breaker, you could get 125amps on each leg of power coming in. That is incorrect. If you draw more than 125amps on that panel, the breaker will kick (actually it will be rated somewhat different but that isn't important here).

Did they have the power company upgrade the incoming service or meter? The feeders from the pole; house; meter; to you box need to be sized properly. If you increase the service you will often have to increase the wire size.

Your future exterior lighting probably isn't a big deal (if you go LED) but a spa can easily draw lots of current. Modern efficient ACs might be in the 30A range plus the blower fan, etc. And the start current will be higher (depending on if you get a softstart option on the compression).

I'd go 200 if I was spending the time and money for the upgrade.


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RE: Advice Needed: How many amps required?

Thanks all. Your advice is consistent with every other person I've talked to.

I know they contacted the utility to investigate but I don't know if they came out and did something or what precisely...

They have changed the wires on the top of the house coming from the pole (we do not have buried utilities in this neighborhood) but I don't know if utility did that or electrician.

I have told GC that this panel is a no-go for us and needs to come out.


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RE: Advice Needed: How many amps required?

"The "electrician" (and I use the word loosely) thinks that with a 125A breaker, you could get 125amps on each leg of power coming in. That is incorrect. If you draw more than 125amps on that panel, the breaker will kick (actually it will be rated somewhat different but that isn't important here)."

Are you serious??? A 125A service is exactly that, 125A on EACH leg. It's 125A @ 240V.


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RE: Advice Needed: How many amps required?

Umm, what the electrician said, in every respect, is correct.

There is absolutely no need for more than a 125 amp panel in a 1400 sf home that has gas heat, water heater and dryer. 200 Amps is way overkill.

Even with A/C and a spa, it will be fine. You could easily accommodate an electric dryer too if you wanted.

As you all (except the OP) are very aware - the main breaker does provide 125 amps, in this case, each to two legs (120 volts) or 125 amps to both legs (240 volts) - with allowances for maximum loading and such.

Especially as we see energy saving lighting and such, the thought that we need 200 amp panels in moderate sized homes where the major appliances are gas is ridiculous.

OP: if you had an all electric house, you would need a 200 amp panel. You would have been fine with 100 amps.


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RE: Advice Needed: How many amps required?

OP: You should know that it's not just the panel. It's the entire service from the drop to the panel that will have to be changed if you go with a larger panel.

If I were the GC or the electrician, I wouldn't be eating the change order unless it specified a larger service in the specs.

What the contractor did isn't wrong or inappropriate - so you need to get out your checkbook for the re-do.


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RE: Advice Needed: How many amps required?

Peter and Jake, as well as your electrician, are 100% correct. You have to be very careful about what you read on the internet, especially when it comes to electricity.


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RE: Advice Needed: How many amps required?

Thanks for the further comments. I will say Joe, however--isn't this the internet too?

What bout electric car charger or two and adding 500 sq ft addition? It's those things I want to flexibility for and don't want to double pay for re-doing this electrical work in 5 years. It seems silly to box myself in when I can just have extra capacity whether not I ever use it.

The service from utility is quite a valid point and I don't know what the deal is with that--I asked him if there was some "technical limitation" this morning and he didn't respond. So not sure if there is an upcharge there.

Re Jake--whose checkbook get's dinged is up for debate. That's the bizarre part of this. I spoke with GC verbally and approved cost of this upgrade. He was supposed to write up a change order for me to approve. None was ever provided and that panel was installed before I ever had a chance to approve or reject specs. I never even approved the work at all and it's not part of my contract so I'm surprised they even did it. The electrical work per spec is to install all the circuits throughout the house and the recessed lighting. The service upgrade was a change order (that never was prepared or issued).

Again thanks.


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RE: Advice Needed: How many amps required?

If you have an electric car in your future and a 500 sq ft addition you would probably be fine with 125 amps as long as you didn't go with other electric appliances like water heater and dryer. BTW: Natural gas is so much cheaper than electricity, would be crazy to do that.

I'm not up on EV charging specs... but it looks like 16 or 30 amps is the standard. if you are talking 16 amps that's nothing... 30 amps becomes a consideration - but still within reasonable on 125 amp panel and all major appliances being gas.

I have a slightly smaller house than you, and put in a new 100 amp panel. Didn't see the need for anything larger. All major appliances are gas.

Yeah, the issue that I have is that the contractor proceeded without having the size of the service decided. That wasn't smart.


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RE: Advice Needed: How many amps required?

Was in a rush to get to work on the earlier post. Often a panel may show 125 amperes on the manufacturer's label and be equipped with a lower-rated breaker-- such as 100 amperes. Also the meter socket (as already referenced in another post). So check all of those. 125 amps for 1400 square feet? Yes, adequate for most situations. But going 200 now is not much more cost. And if a future addition to the house should occur, it probably would be needed.
My beef with the electrician is that he seems to not know if it is 125 amps or 100 amps-- based on what is posted.
In this area, the homeowner ( or his checkbook) supplies the service riser and weather head for overhead services and the POCO does as they darn well please from there. I upgraded one service from 100 to 200 because of switching from gas furnace to heat pump. The POCO did not change the service drop even though I know it is undersized.


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RE: Advice Needed: How many amps required?

Yes it is 125A at 240V. What I was commenting on was the implication that you could just multiply by two. With the spa and AC being 240V equipment, you have to consider that. If you only had 120V breakers, then yes.


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RE: Advice Needed: How many amps required?

"The POCO did not change the service drop even though I know it is undersized."

Yep, I've had the same experience.


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RE: Advice Needed: How many amps required?

If you are doing a complete gut and rehab including a new service, what did the load calculations on your drawings come to? Usually these are required during the permitting stage. Using that calculation you can then add your future expected loads to see where you are at.


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RE: Advice Needed: How many amps required?

OP:

Of course Joefixit's post is correct, you can do a load calc and add your future demands and you will know where you are.

And if you want to go with 150 amp or 200 amp service, that's fine. I think 200 is over-kill for your situation... but whatever.

I was reacting to the posters who seemed to be implying that a 125 amp service was not correct or that your electrician / GC didn't know what they were doing - there's nothing that you have said so far that would indicate either is true.


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RE: Advice Needed: How many amps required?

IMO 125A is NOT enough to allow for any expansion in this installation. Sure, for the main all gas 1400 sq/ft house it'll be fine probably forever, BUT.... breaker space will go away very fast and more than likely a sub-panel will be required, and with the proposed expansion (car plus an additional 1k sq/ft) I personally think 125A is absurd.

Also, 150A is a "b@stard" service size in today's world. There is absolutely NO reason to go with 150A, other than maybe a few dollars in savings. And I do mean only a few dollars.
In all but the tiniest of homes, 200A is SOP today.
When you figure a 100A service plus a sub-panel it makes no sense compared to a 200A service.


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RE: Advice Needed: How many amps required?

I spoke with GC verbally and approved cost of this upgrade. He was supposed to write up a change order for me to approve. None was ever provided and that panel was installed before I ever had a chance to approve or reject specs. I never even approved the work at all and it's not part of my contract so I'm surprised they even did it. The electrical work per spec is to install all the circuits throughout the house and the recessed lighting. The service upgrade was a change order (that never was prepared or issued).

It sounds like your beef is with the GC - not the electrician.


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RE: Advice Needed: How many amps required?

Thanks all. I won the battle on this one with just a heated email to the GC.

The fact is, I am paying for 200amp service upgrade (I know how much it should cost because I bid all the work to 3 GCs before choosing this one so I've got 3 prices for the service upgrade) and GC and/or electrician was pocketing a few hundred extra by using load calcs to justify 125 amp. I am sure all of these calculations were done correctly and 125 amp is totally fine for this house...now. The fact is, they were never shared with me or discussed with me and if they had been I would have pointed out all these other planned expansions that are not part of the current scope of work and rejected the specification.

Again, I appreciate everyone's input and feel much more knowledgable about his topic. I may be overkilling with 200, but it is highly conceivable that 125 will be tapped with our future plans. This will be our house for a long time--happy to pay for quality electrical work, but I don't want future invoices to ever say anything about "service upgrade" again.


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RE: Advice Needed: How many amps required?

The fast charger for a Tesla uses 70A at 240V.

The trend going forward will be for faster charges at higher amperages and I would expect that Ford/Cheyy/Honda etc will catch up with the likes of Tesla over time until the 15 min recharge is achieved.

Granted at home you usually have much more time than that to recharge, but a fast option is nice to have.


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RE: Advice Needed: How many amps required?

Definitely put the extra in, electric car charging is going to be a lot more common and teh extra cost is minimal when you already have the project underway.


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