#304592 - 30/11/2007 22:05
Electrical question
|
carpal tunnel
Registered: 27/06/1999
Posts: 7058
Loc: Pittsburgh, PA
|
The house I recently bought has 100A electric service. The previous owners had a gas dryer, but I already have an electric dryer, and want to use it. Unfortunately, there's no 240V plug for a dryer, and electricians I've talked to are telling me I need to upgrade my service to 150A if I want to add an electric dryer. I figure there are smart folks here who might be able to double check their math. Here's a picture of my breaker panel:  There are no more usable spaces on the panel, so I'd probably have to do have a sub-panel installed if I keep the 100A service. The big-ticket electric appliances in my house are the A/C, range/oven, and dishwasher. The water heater and furnace are gas-powered. I can just buy a gas dryer for ~$350, whereas upgrading to 150A service will cost almost $1000. If I'm really at the limit of what 100A service can do, it might make sense for me to upgrade, but if there's room for my dryer with my existing setup, I'd rather upgrade later. Has anyone run into this kind of problem before?
|
|
Top
|
|
|
|
|
#304593 - 30/11/2007 23:39
Re: Electrical question
[Re: tonyc]
|
old hand
Registered: 17/01/2003
Posts: 998
|
Please wait for someone smarted than me to chime in but here’s how I’d figure it. You can probably look at your furnace, AC, range and dishwasher and find a current rating somewhere. You could add that up, plus 10%,, to see if their right (bet they are). Guesses for breakers: Furnace – 30 amp Dishwasher – 20 amp Range - 50 amp Total house outlet breakers – 40 amp Dryer – 30 amps Total – 170 amps As you noticed this is more that 100 amps without your dryer. That’s because hopefully all your appliances aren’t shorting out at once. I would just add another 30 amp fuse and see. If the main trips often upgrade or buy a gas dryer. A 30 amp breaker is not that much. Chances are you won’t have everything on at once (especially the furnace and AC). Heck, I’d probably just hook into the furnace or range breaker. I have a smoke detector.  But probably to be on the up-and up you’d need more than 100 amp service. Looks like there are punch out panels next to the main. Maybe you can place a breaker in there.
|
|
Top
|
|
|
|
|
#304594 - 01/12/2007 00:04
Re: Electrical question
[Re: Redrum]
|
carpal tunnel
Registered: 25/12/2000
Posts: 16706
Loc: Raleigh, NC US
|
The label over those reads "DO NOT ____ THIS K.__". I'm guessing it's "Do not remove this K.O. (knockout)". I don't know why, but I can't imagine they would put that label on there for no reason.
_________________________
Bitt Faulk
|
|
Top
|
|
|
|
|
#304595 - 01/12/2007 10:41
Re: Electrical question
[Re: wfaulk]
|
old hand
Registered: 01/10/2002
Posts: 1039
Loc: Fullerton, Calif.
|
Whom ever put the "do not remove" sticker on that knockout wasn't even smart enough to get it right side up. I'll bet there's just another breaker socket under it.
Code requires that the feed be large enough to run everything at once. Licensed electricians have to follow the code, as should anyone. ... However, you could just hook up your drier to that 50 amp breaker for the range and just not run the range and drier at the same time. Or add a breaker and just not run the drier and one of the other big ticket items at the same time. I have to do this in my house because while it has about a dozen breakers, apparently all of the things in the house are hooked to just one of them...
Also, those appear to be GE breakers. If you have nuisance tripping problems, try swapping them out for Square-D HOM series breakers. They are much higher quality and won't trip when they should not.
|
|
Top
|
|
|
|
|
#304596 - 01/12/2007 11:21
Re: Electrical question
[Re: larry818]
|
carpal tunnel
Registered: 29/08/2000
Posts: 14491
Loc: Canada
|
Quote:
Whom ever put the "do not remove" sticker on that knockout wasn't even smart
enough to get it right side up. I'll bet there's just another breaker socket under it.
The sticker was probably put there for the initial installation, which generally requires
that a pair of (opposing) 120V legs be left unused for future (240V) expansion.
If that's actually the case (open it up to find out), then the dryer could now use
those two slots, unless there's some other relevant code requirement here.
Quote:
Code requires that the feed be large enough to run everything at once.
Mmm.. I'd like to see a real citation for that somewhere.
Standard code is a 200A panel for up to 40 circuits.
Figure the minimum of 15A per circuit, we get 600 total at 120V.
Dividing by 2 for 240V gives us 300A of circuits on a 200A panel.
Cheers
Edited by mlord (01/12/2007 11:23)
|
|
Top
|
|
|
|
|
#304597 - 01/12/2007 11:27
Re: Electrical question
[Re: Redrum]
|
carpal tunnel
Registered: 29/08/2000
Posts: 14491
Loc: Canada
|
Quote:
Guesses for breakers:
Furnace – 30 amp
Dishwasher – 20 amp
Range - 50 amp
Total house outlet breakers – 40 amp
Dryer – 30 amps
The Dishwasher would only count as 10 amps in that simple calculation,
because it's a 120V circuit. (Things are actually slightly more complex than that,
but not enough to matter for this purpose).
|
|
Top
|
|
|
|
|
#304598 - 01/12/2007 11:32
Re: Electrical question
[Re: mlord]
|
carpal tunnel
Registered: 29/08/2000
Posts: 14491
Loc: Canada
|
Quote:
Quote:
Whom ever put the "do not remove" sticker on that knockout wasn't even smart
enough to get it right side up. I'll bet there's just another breaker socket under it.
The sticker was probably put there for the initial installation, which generally requires
that a pair of (opposing) 120V legs be left unused for future (240V) expansion.
Oh, wait a minute.. I've figured this one out:
The blank slot covers are beside the 100A master breaker.
Which means there probably are NOT any usable slots under them.
So the panel is probably already maxed out, and to expand it
a subpanel is needed. And two circuits must move from the main
to the sub, in order to free two slots to connect the sub to the main.
Or just install a bigger panel, which will first require (code) a larger
mains service (eg. 200A) to be installed. I did all of this myself for our
house here many years ago, and it all passed inspection just fine.
If you took the cover off and posted a photo of the innards,
then we could tell for sure. Of course you may kill yourself
in the process, so try and use good judgement there.
Cheers
Edited by mlord (01/12/2007 11:34)
|
|
Top
|
|
|
|
|
#304599 - 01/12/2007 11:43
Re: Electrical question
[Re: mlord]
|
old hand
Registered: 17/01/2003
Posts: 998
|
Quote:
Quote:
Guesses for breakers:
Furnace – 30 amp
Dishwasher – 20 amp
Range - 50 amp
Total house outlet breakers – 40 amp
Dryer – 30 amps
The Dishwasher would only count as 10 amps in that simple calculation,
because it's a 120V circuit. (Things are actually slightly more complex than that,
but not enough to matter for this purpose).
Yea, I thought I was a little high on the dishwasher. I figured maybe some of the units that heat water quickly may draw a bit more
|
|
Top
|
|
|
|
|
#304600 - 01/12/2007 11:51
Re: Electrical question
[Re: Redrum]
|
carpal tunnel
Registered: 29/08/2000
Posts: 14491
Loc: Canada
|
Quote:
Quote:
Quote:
Guesses for breakers:
Furnace – 30 amp
Dishwasher – 20 amp
Range - 50 amp
Total house outlet breakers – 40 amp
Dryer – 30 amps
The Dishwasher would only count as 10 amps in that simple calculation,
because it's a 120V circuit. (Things are actually slightly more complex than that,
but not enough to matter for this purpose).
Yea, I thought I was a little high on the dishwasher
I figured maybe some of the units that heat water quickly may draw a bit more
Yes, your 20A number was totally correct (code, actually),
but it's 20A at 120V, whereas all of the other numbers given there
were for 240V circuits. So the DW really only counts for 10A
when considered for the 240V sums. That's all.
Cheers
|
|
Top
|
|
|
|
|
#304601 - 01/12/2007 11:57
Re: Electrical question
[Re: tonyc]
|
carpal tunnel
Registered: 29/08/2000
Posts: 14491
Loc: Canada
|
Quote:
The house I recently bought has 100A electric service. The previous owners had a gas dryer, but I already have an electric dryer, and want to use it. Unfortunately, there's no 240V plug for a dryer, and electricians I've talked to are telling me I need to upgrade my service to 150A if I want to add an electric dryer.
I would install a gas dryer and pocket the instant savings for not upgrading the service
plus the ongoing usage savings (should be about 50-60% of the cost of electricity).
But if you do go for a service upgrade, here's what the pieces are:
(1) Wires from the utility pole to your house --> usually free, courtesy of the utility.
(2) Wires from the outside of the house to the meter, and from there to your panel:
probably need to be upgraded, but they might already be large enough for 150A.
The electricians will know (TEWK).
(3) The meter socket/box: may need to be upgraded (replaced). TEWK.
Note that the meter itself is a freebie.
(4) The panel itself: $50-$100.
(5) A new mains breaker: $50-$100.
(6) New breakers for all circuits: Perhaps $10 per 120A circuit.
If you get a same-brand panel as the old one, then the old breakers
can probably be reused without issues. Specify that to the electricians.
(7) Labour for all of this: just add up the parts, double it, and there's the labour cost
(total parts+labour cost is 3X parts cost alone)
EDIT:
(8) A new grounding rods/plates system may be needed, figure $200 for parts.
Edited by mlord (01/12/2007 12:04)
|
|
Top
|
|
|
|
|
#304602 - 01/12/2007 12:00
Re: Electrical question
[Re: mlord]
|
old hand
Registered: 17/01/2003
Posts: 998
|
Yes, 20 amp 120v. Sorry for talking apples and oranges.
|
|
Top
|
|
|
|
|
#304603 - 01/12/2007 12:05
Re: Electrical question
[Re: tonyc]
|
old hand
Registered: 17/01/2003
Posts: 998
|
One other thing. If you do upgrade give yourself room to grow. If you plan on having a garage with an air compressor, welder or other big power tools these will bump up your needs.
My old 5 hp air compressor realy pushes the 20 amp 240v breaker at startup.
|
|
Top
|
|
|
|
|
#304604 - 01/12/2007 12:06
Re: Electrical question
[Re: Redrum]
|
carpal tunnel
Registered: 29/08/2000
Posts: 14491
Loc: Canada
|
Quote:
My old 5 hp air compressor realy pushes the 20 amp 240v breaker at startup.
No surprise there. 30A@240V is normally used for 5hp motors.
Cheers
Edited by mlord (01/12/2007 12:07)
|
|
Top
|
|
|
|
|
#304605 - 01/12/2007 13:04
Re: Electrical question
[Re: mlord]
|
carpal tunnel
Registered: 25/12/2000
Posts: 16706
Loc: Raleigh, NC US
|
Quote:
The blank slot covers are beside the 100A master breaker.
Which means there probably are NOT any usable slots under them.
Do you think that the main breaker uses the whole of the hot bus bars' poles and not just the left or right half like a "normal" breaker? I was kinda guessing that, too, but my main breaker is not in the service panel, and I couldn't find any documentation online to support that.
_________________________
Bitt Faulk
|
|
Top
|
|
|
|
|
#304606 - 01/12/2007 13:22
Re: Electrical question
[Re: wfaulk]
|
carpal tunnel
Registered: 29/08/2000
Posts: 14491
Loc: Canada
|
Quote:
Quote:
The blank slot covers are beside the 100A master breaker.
Which means there probably are NOT any usable slots under them.
Do you think that the main breaker uses the whole of the hot bus bars' poles
and not just the left or right half like a "normal" breaker?
That's how his panel is labelled, anyway.
On the 200A panel I installed here, the top portion (clearly separate) is for the mains.
I began with a 100A breaker in there, which took up half of the space,
and then later (after I upgraded the outside service) replaced it with a 200A
breaker, which took up all of the space (both sides).
I'm guessing that his panel has a similar arrangement internally,
with both sides dedicated for the mains breaker, even if the existing
100A device is only using half of the space currently (pun intended).
Cheers
|
|
Top
|
|
|
|
|
#304607 - 01/12/2007 13:28
Re: Electrical question
[Re: mlord]
|
carpal tunnel
Registered: 29/08/2000
Posts: 14491
Loc: Canada
|
Quote:
I'm guessing that his panel has a similar arrangement internally,
with both sides dedicated for the mains breaker, even if the existing
100A device is only using half of the space currently (pun intended).
Mmm.. on reflection, I'm not totally convinced of this, though.
Actually, it's probably more a code/safety issue that has those
two extra slots labeled as "do not use". The mains breakers are
supposed to be isolated from the rest, and perhaps leaving the
two adjacent slots blank is a way to (barely) satisfy code there.
New panel time.
|
|
Top
|
|
|
|
|
#304608 - 01/12/2007 14:20
Re: Electrical question
[Re: mlord]
|
old hand
Registered: 01/10/2002
Posts: 1039
Loc: Fullerton, Calif.
|
Quote:
Mmm.. I'd like to see a real citation for that somewhere.
I haven't seen any references to code so far, so I'll be the first...
Evidenty I was wrong, but then, my experience is all industrial. For residences, you can shave the amps:
NEC 220.30 Optional Calculation — Dwelling Unit.
I won't cut and paste the code here but here's a link to an article that explains it all well enough...
http://www.automationmedia.com/Port1050%5CSiemensFreeCourses%5Cload_3.pdf
In any case, I could spend all day thinking of more fun ways to spend a couple of grand than to spend it on a new load center.... The worst that could happen if he overloads the breakers is that they will trip. I would just hook it up and learn not to run the range at the same time.
Personally, I would just buy a gas drier. You'll save the price in the first year in utility cost...
|
|
Top
|
|
|
|
|
#304609 - 01/12/2007 14:44
Re: Electrical question
[Re: larry818]
|
carpal tunnel
Registered: 25/12/2000
Posts: 16706
Loc: Raleigh, NC US
|
We've been doing some calculations in IRC on the utility cost. About 29¢ per load for electricity and 19¢ per load for gas (ignoring the gas dryer's electrical consumption). Assuming he did a load of laundry every day, that's $36.50 savings per year.
_________________________
Bitt Faulk
|
|
Top
|
|
|
|
|
#304610 - 01/12/2007 15:47
Re: Electrical question
[Re: wfaulk]
|
carpal tunnel
Registered: 29/08/2000
Posts: 14491
Loc: Canada
|
Quote:
We've been doing some calculations in IRC on the utility cost.
About 29¢ per load for electricity and 19¢ per load for gas
(ignoring the gas dryer's electrical consumption).
Assuming he did a load of laundry every day, that's $36.50 savings per year.
You must have really cheap electricity for a load to cost only 29¢.
I figure it takes about an hour a load, so that's 4-6kWH per load.
At 12¢ per kWH, that's about 60¢ a load.
Odds are good that the electricity cost is higher than 12¢ per kWH there, though.
Cheers
Edited by mlord (01/12/2007 15:47)
|
|
Top
|
|
|
|
|
#304611 - 01/12/2007 17:02
Re: Electrical question
[Re: mlord]
|
carpal tunnel
Registered: 25/12/2000
Posts: 16706
Loc: Raleigh, NC US
|
Tony's was 7.18¢ per kWh. Mine is 9.4¢. And, for the record, my gas is $1.34 per therm and his is $8.67 per Mcf.
I found statistics that claimed about 4kWh of electricity or 0.22 therms of gas per load.
On a related subject, I can't believe that the gas company sells gas in units based on heat generation rather than on volume, even if it does more-or-less equal 100cf. But there you go.
Edited by wfaulk (01/12/2007 17:06)
_________________________
Bitt Faulk
|
|
Top
|
|
|
|
|
#304612 - 01/12/2007 17:54
Re: Electrical question
[Re: mlord]
|
old hand
Registered: 01/10/2002
Posts: 1039
Loc: Fullerton, Calif.
|
Quote:
You must have really cheap electricity for a load to cost only 29¢.
My local electric company's web site says 14.5¢ / kwh, but it doesn't mention all the taxes on top of that.
Sans taxes, I guess that's only $315 / year to run an electric dryer an hour a day.
The best info I found on gas dryers only said that they are about $50 / year cheaper to run than electric....
|
|
Top
|
|
|
|
|
#304613 - 01/12/2007 17:57
Re: Electrical question
[Re: wfaulk]
|
old hand
Registered: 01/10/2002
Posts: 1039
Loc: Fullerton, Calif.
|
Quote:
Tony's was 7.18¢ per kWh. Mine is 9.4¢. And, for the record, my gas is $1.34 per therm and his is $8.67 per Mcf.
My local gas co is 63.555 ¢/therm.
|
|
Top
|
|
|
|
|
#304614 - 02/12/2007 19:40
Re: Electrical question
[Re: larry818]
|
addict
Registered: 23/01/2002
Posts: 506
Loc: The Great Pacific NorthWest
|
From what I can see the sticker is not attached upside down, the panel is. That being the case I also suspect that the stick is factory installed which would indicate that there is a good reason not the remove the K.O.'s Lots of assumptions there but that's what it looks like to me. Mains are typically on the top and generally on the left but not always. If this was my place I would look into replacing the existing panel with a new larger one. There is no room for expansion in this system. I would also look into the logistics of increasing the service size. Again, not knowing what you're up against makes this impossible to give good advice. Where is the meterbase in respect to the panel? WAC (Washington State) rules spec that it must be no further the 15' from the service breaker. You can purchase a GE panel and use your existing breakers for all of the existing loads. I don't see a way to go with an electric dryer without a service size increase but using the existing breakers would probably be the cheapest solution. Depending on the age of your home you may need to drive another ground rod but that is easy to do and fairly cheap.
Edited by Neutrino (02/12/2007 20:01)
_________________________
No matter where you might be, there you are.
|
|
Top
|
|
|
|
|
#304615 - 02/12/2007 21:07
Re: Electrical question
[Re: larry818]
|
pooh-bah
Registered: 09/08/2000
Posts: 2091
Loc: Edinburgh, Scotland
|
Quote:
Quote:
Tony's was 7.18¢ per kWh. Mine is 9.4¢. And, for the record, my gas is $1.34 per therm and his is $8.67 per Mcf.
My local gas co is 63.555 ¢/therm.
And I am totally baffled - don't know if I have any info anywhere as to how much I pay for what units... I know I spend less on electricity a year than mobile phones, and less on mobile phones a quarter than petrol a week.
Other than that... I needed to google just to find out what a therm and a Mcf were anyway:-)
_________________________
Rory
MkIIa, blue lit buttons, memory upgrade, 1Tb in Subaru Forester STi
MkII, 240Gb in Mark Lord dock
MkII, 80Gb SSD in dock
|
|
Top
|
|
|
|
|
#304616 - 02/12/2007 22:07
Re: Electrical question
[Re: Neutrino]
|
old hand
Registered: 01/10/2002
Posts: 1039
Loc: Fullerton, Calif.
|
Quote:
From what I can see the sticker is not attached upside down, the panel is.
You may be right, it seems all the original stickers are upside down. It's strange, tho, as panels normally open from right to left as this one has in the picture. The panel here in my old office opens left to right, tho... as do a few others I find on the 'net...
Main breakers are typically at the top, too.
Gotta love standards...
|
|
Top
|
|
|
|
|
#304617 - 03/12/2007 01:24
Re: Electrical question
[Re: larry818]
|
carpal tunnel
Registered: 29/08/2000
Posts: 14491
Loc: Canada
|
Quote:
Quote:
From what I can see the sticker is not attached upside down, the panel is.
You may be right, it seems all the original stickers are upside down. It's strange, tho, as panels normally open from right to left as this one has in the picture. The panel here in my old office opens left to right, tho... as do a few others I find on the 'net...
Main breakers are typically at the top, too.
Gotta love standards...
My guess is that the service wires enter from the bottom,
underground service, perhaps. But then where is the meter box ?
Cheers
Edited by mlord (03/12/2007 01:24)
|
|
Top
|
|
|
|
|
#304618 - 04/12/2007 05:27
Re: Electrical question
[Re: mlord]
|
carpal tunnel
Registered: 27/06/1999
Posts: 7058
Loc: Pittsburgh, PA
|
Epilogue:
I spent some time yesterday looking at gas dryers, and I realized it'd actually be closer to $500 including delivery to get a gas dryer with the same features of my current electric model, the most important of which being a moisture sensor. Staring at a $500 investment for little-to-no gain or $1000 to replace the panel, I decided to give one more electrician a call.
He came out and looked at my panel and told me that he could add the dryer plug to one of the existing upstairs circuits that didn't have a lot of load on it. Things seem to be running smoothly now, and I've got my dryer going as I type. He did say that this is the end of the road for this panel, both in terms of load and in terms of the physical shape of the panel.
He did the work for about 1/3 of what the dryer would have cost me, so if I squeeze some years out of the dryer, it was a good investment, and if I never have to replace my breaker panel, it was definitely the right choice. We'll see, but as someone who just shelled out big paper for down payment and closing costs, I think this was a decent stop-gap measure. Thanks for all the advice and info, everyone.
Now, to see if the Christmas lights push this whole darn thing over the edge...
Edited by tonyc (04/12/2007 05:30)
|
|
Top
|
|
|
|
|
#304619 - 04/12/2007 18:08
Re: Electrical question
[Re: tonyc]
|
addict
Registered: 23/01/2002
Posts: 506
Loc: The Great Pacific NorthWest
|
I wonder if he connected it to your A/C or the Range?
_________________________
No matter where you might be, there you are.
|
|
Top
|
|
|
|
|
#304620 - 04/12/2007 18:49
Re: Electrical question
[Re: Neutrino]
|
old hand
Registered: 17/01/2003
Posts: 998
|
Quote:
I wonder if he connected it to your A/C or the Range?
I bet he did.
"Upstairs circuits" are no doubt 120V not 240V
|
|
Top
|
|
|
|
|
#304621 - 04/12/2007 19:56
Re: Electrical question
[Re: Redrum]
|
carpal tunnel
Registered: 27/06/1999
Posts: 7058
Loc: Pittsburgh, PA
|
Sorry, I was unclear. I believe what he did was combined two of the upstairs circuits into one, creating a new 240V circuit, and put the dryer on that. There were two smaller breakers left over after he was done.
|
|
Top
|
|
|
|
|
|
Previous Topic
Index