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major domo
 
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Default Electrical service question - old house, new addition - expert advice needed

Hi,

I have an electrical service question and have gotten 2 or 3 different
answers.
You can probably tell, but I am a novice. Maybe someone here can help.

I have a 1000 sq ft brick/slab foundation house in the U.S. (electric water
heater, electric dryer, electric stove, no central air) that is 40 years old
(grey cloth-covered copper wire).

Outside the house is a meter and separate breaker box with a two 30amp and
two 20 amp breakers. Two circuits from this outside box run along the
outside of the house to an electric dryer and private sewer system.

Inside the house directly through the brick wall is an inside main with no
main breaker visible.
In the inside box (12 slot), there are 8 breakers: One 100 amp double throw
(stove), one 60 amp double throw (electric water heater - which will be
probably be replaced with a LP unit during the remodel), one 30 amp double
throw (?), and a mixture of 20 amp single and double throws.
One slot is empty.

I am adding a 600 sq ft addition to this house, and adding electric central
air heating and cooling. It is a 4 ton unit. (60 to 80 amp heater?)

Here are the two options suggested to me already.

1) The HVAC installer recommended upgrading the outside meter and breaker
combination ("meter main") to 200 amps and then feeding the old inside main
from one larger outside breaker.
He then suggested running a wire (presumably from another outside breaker)
the 60 foot distance through the attic to a new 200 amp inside main
underneath the central air heater (which is in the attic). This main would
also serve the new addition. I will probably move the electric stove to use
this new service, since the wiring in the area is now exposed. I assume he
would power the outside air conditioning compressor (40 feet away) with a
third breaker from the new 200 amp outside main. He suggested 6/3 wire for
the 60 foot run through the attic.

After some consideration, I began to think that the single line to the new
200 amp inside main would be overloaded unless it was very large.

2) A suggestion from another individual involved the following layout:
Upgrade the outside main ("meter main") to a 200 amp unit. Run one breaker
to the old inside main. Run another outside breaker and wire directly to the
central heater through the attic (60 feet). Run a third outside breaker and
wire through the attic to the new inside main (60 feet), which could be now
be 100 amp (20 circuit), since the central heater has it's own circuit. Run
the fourth breaker and wire outside the house to the air conditioning
compressor (40 feet). He suggested using 4/3 or 2/3 wire for the 60 foot
runs through the attic.

Here are my questions:

a) Which arrangement would you use that meets NEC code? Are there more
options?
b) I would prefer not to change out the old inside main, unless it's of
great advantage.
c) Also, do I need subpanels for the central heater and air conditioning
compressor?
d) What gauge of wire is acceptable to use for 60 foot runs through the
attic? Should it be enclosed in a pipe? (the attic is vaulted ceiling with
very little (2 feet) crawling room)
e) Last, is it okay to have a single main breaker/smaller breaker box on the
new inside main (60 feet away from outside service) or should it be a
subpanel as well?

Sorry to be so long-winded, but I wanted to be thorough.
I would *greatly* appreciate any expert help in this matter.

Thank you!






  #2   Report Post  
Mark or Sue
 
Posts: n/a
Default Electrical service question - old house, new addition - expert advice needed

"major domo" wrote in message
.. .
I have an electrical service question and have gotten 2 or 3 different
answers.
You can probably tell, but I am a novice. Maybe someone here can help.

I have a 1000 sq ft brick/slab foundation house in the U.S. (electric

water
heater, electric dryer, electric stove, no central air) that is 40 years

old
(grey cloth-covered copper wire).

Outside the house is a meter and separate breaker box with a two 30amp and
two 20 amp breakers. Two circuits from this outside box run along the
outside of the house to an electric dryer and private sewer system.

Inside the house directly through the brick wall is an inside main with no
main breaker visible.
In the inside box (12 slot), there are 8 breakers: One 100 amp double

throw
(stove), one 60 amp double throw (electric water heater - which will be
probably be replaced with a LP unit during the remodel), one 30 amp double
throw (?), and a mixture of 20 amp single and double throws.
One slot is empty.

I am adding a 600 sq ft addition to this house, and adding electric

central
air heating and cooling. It is a 4 ton unit. (60 to 80 amp heater?)

Here are the two options suggested to me already.

1) The HVAC installer recommended upgrading the outside meter and breaker
combination ("meter main") to 200 amps and then feeding the old inside

main
from one larger outside breaker.
He then suggested running a wire (presumably from another outside breaker)
the 60 foot distance through the attic to a new 200 amp inside main
underneath the central air heater (which is in the attic). This main would
also serve the new addition. I will probably move the electric stove to

use
this new service, since the wiring in the area is now exposed. I assume he
would power the outside air conditioning compressor (40 feet away) with a
third breaker from the new 200 amp outside main. He suggested 6/3 wire for
the 60 foot run through the attic.

After some consideration, I began to think that the single line to the new
200 amp inside main would be overloaded unless it was very large.

2) A suggestion from another individual involved the following layout:
Upgrade the outside main ("meter main") to a 200 amp unit. Run one breaker
to the old inside main. Run another outside breaker and wire directly to

the
central heater through the attic (60 feet). Run a third outside breaker

and
wire through the attic to the new inside main (60 feet), which could be

now
be 100 amp (20 circuit), since the central heater has it's own circuit.

Run
the fourth breaker and wire outside the house to the air conditioning
compressor (40 feet). He suggested using 4/3 or 2/3 wire for the 60 foot
runs through the attic.

Here are my questions:

a) Which arrangement would you use that meets NEC code? Are there more
options?
b) I would prefer not to change out the old inside main, unless it's of
great advantage.
c) Also, do I need subpanels for the central heater and air conditioning
compressor?
d) What gauge of wire is acceptable to use for 60 foot runs through the
attic? Should it be enclosed in a pipe? (the attic is vaulted ceiling with
very little (2 feet) crawling room)
e) Last, is it okay to have a single main breaker/smaller breaker box on

the
new inside main (60 feet away from outside service) or should it be a
subpanel as well?


What you've posted seems confused, as parts don't make sense. I'm hoping you
have your breakers labeled wrong, and am guessing what you have is the
following in the inside panel:

100A main
60A for stove
30A water heater
misc 15A and 20A branch circuits

For what you want, you will need a 200A service and perhaps more (you'll
have no expansion to grow w/200A). You may want to go with a 320A service if
you're going to the trouble of replacing your service. Both options 1 and 2
are NEC compliant except that 6/3 can only support a 60A panel. If you
really want a 200A indoor subpanel, you'll need a 2/0 copper feeder with 4
wires which is huge, and the main panel must have feed through lugs
(uncommon). I would lean towards option 2, but it may look ugly on the
outside of your house with all the feeders coming out of it. If you have an
outside main disconnect (breaker), all the inside panels must have their
ground and neutral busses separated. Only the ground bus can touch the
chassis on a subpanel, the neutral must remain insulated. If your existing
100A inside panel is not isolated like this, it could be difficult to make
it compliant (wires too short).

The central heat and A/C need disconnects, but not necessarily subpanels. If
this is a heat pump, the part with resistance heat will need a lot of amps.
Best to run a circuit from the main panel to just handle this load (which
will probably have to be #4 or #2 copper).

The wires in the attic are sized by the size breaker protecting them and not
necessarily length. But with a 60' length, I'd be inclined to stay with the
larger choice if a borderline wire size is needed. Wires do not have to be
in conduit if a cable type wire is used, but must be protected from physical
damage. Your low attic sounds like you may just be able to fish the cable
through and staple it down where you can.

When you ask about an inside "main" I'm not sure what you mean. It is OK to
have a subpanel inside with its own main breaker, but a main breaker is not
required in a subpanel inside your house. If you want a "service rated
panel" inside, it usually must have a main. Only problem is, all your
"service rated" disconnects must be grouped near each other (can't have one
outside and one inside). If you have an outside disconnect, that is the only
main you need, and all other should be subpanels. You could have another
panel next to that outside disconnect that is also a "service rated" panel,
but you usually only do this when you have a larger service than the panel
is rated for (e.g. 300A service with a 100A and 200A panel side by side).

Hopefully this helped and didn't confuse you too much. You may want to post
again with new questions. I'd recommend talking to an electrical contractor
to see what they recommend. Be sure you know the amp requirements of the new
heat pump (both inside and outside units) and anything else you want to add
that is power intensive (larger range, hot tub, welder,...). Sometimes, HVAC
contractors can do some really weird things with power, but then so can lame
electrical contractors. Be prepared for the electrical costs to top $1000
for all of this, and even more if your electric utility company charges to
upgrade the service drop and/or transformer to your house.

--
Mark
Kent, WA



  #3   Report Post  
major domo
 
Posts: n/a
Default Electrical service question - old house, new addition - expert advice needed


"Mark or Sue" wrote in message
news:HdCub.183851$275.602329@attbi_s53...

For what you want, you will need a 200A service and perhaps more (you'll
have no expansion to grow w/200A). You may want to go with a 320A service

if
you're going to the trouble of replacing your service. Both options 1 and

2
are NEC compliant except that 6/3 can only support a 60A panel. If you
really want a 200A indoor subpanel, you'll need a 2/0 copper feeder with 4
wires which is huge, and the main panel must have feed through lugs
(uncommon). I would lean towards option 2, but it may look ugly on the
outside of your house with all the feeders coming out of it. If you have

an
outside main disconnect (breaker), all the inside panels must have their
ground and neutral busses separated. Only the ground bus can touch the
chassis on a subpanel, the neutral must remain insulated. If your existing
100A inside panel is not isolated like this, it could be difficult to make
it compliant (wires too short).

The central heat and A/C need disconnects, but not necessarily subpanels.

If
this is a heat pump, the part with resistance heat will need a lot of

amps.
Best to run a circuit from the main panel to just handle this load (which
will probably have to be #4 or #2 copper).

The wires in the attic are sized by the size breaker protecting them and

not
necessarily length. But with a 60' length, I'd be inclined to stay with

the
larger choice if a borderline wire size is needed. Wires do not have to be
in conduit if a cable type wire is used, but must be protected from

physical
damage. Your low attic sounds like you may just be able to fish the cable
through and staple it down where you can.

When you ask about an inside "main" I'm not sure what you mean. It is OK

to
have a subpanel inside with its own main breaker, but a main breaker is

not
required in a subpanel inside your house. If you want a "service rated
panel" inside, it usually must have a main. Only problem is, all your
"service rated" disconnects must be grouped near each other (can't have

one
outside and one inside). If you have an outside disconnect, that is the

only
main you need, and all other should be subpanels. You could have another
panel next to that outside disconnect that is also a "service rated"

panel,
but you usually only do this when you have a larger service than the panel
is rated for (e.g. 300A service with a 100A and 200A panel side by side).

Hopefully this helped and didn't confuse you too much. You may want to

post
again with new questions. I'd recommend talking to an electrical

contractor
to see what they recommend. Be sure you know the amp requirements of the

new
heat pump (both inside and outside units) and anything else you want to

add
that is power intensive (larger range, hot tub, welder,...). Sometimes,

HVAC
contractors can do some really weird things with power, but then so can

lame
electrical contractors. Be prepared for the electrical costs to top $1000
for all of this, and even more if your electric utility company charges to
upgrade the service drop and/or transformer to your house.

--
Mark
Kent, WA


First,
*Thank you* for reading this and taking your time to reply, Mark!

I hired an electrician to come out and give a consult since I wrote the
questions.
He suggested option 1 at first (200A inside panel for heater and addition,
60' away from outside disconnect)
After he left, I checked the ampacity of the wire needed to feed option 1
and was told I'd need 4/0 feeder wire (at $7.50 a foot!) to carry
potentially 200amps.

After reading your analysis and calling the electrician back, he said I
could optionally run 2 wires (one dedicated to inside heater, one to a
100amp panel) instead of 1 wire to do both.
That way I could run 4/3 copper 60' through the attic directly to the
heater (heater only) and 2/3 copper 60' through the attic to a 100amp panel
for the addition (lights, sockets, stove, dryer, sewerage pump) (instead of
a 200amp panel as per option 1), and have an outside breaker for each
seperate circuit (total of 4 circuits - old inside panel, new inside panel,
central air heater, outside compressor).
It intuitively seems to be a better solution to distribute the load over 2
wires instead of 1.

I rechecked my old inside main, and there is indeed a 100amp single throw
double breaker for the stove. At least when I throw it, the stove is off,
but other lights are on. The stove consists of a separate oven and rangetop.
Have no idea why the original homeowners installed a 100amp breaker, but
it's there. I'm guessing the wire coming from it is a #6.

BTW, the new central air and electric heater is a Goodman 4 ton 13 SEER
conventional unit (not a heat pump)
According to option 2 (which is what I'm tending towards now), the heater
will have it's own dedicated circuit from the outside meter base and
breaker.
Should I also have an second inside breaker/disconnect for the heater at the
heater location (which is right above the new panel, in the new attic)?

I appreciate your mention of separating the ground and neutral busses on the
subpanel.
I don't know if the exisiting inside panel is able to be ground and netural
separated. I do know that most of the wires going through the exisiting
structure do not have a ground wire. It is also good to know that a subpanel
can have a main breaker (that was a hard one to find an answer to). Home
Repo suggested that a subpanel without a main breaker (main lug?) had to be
used if the distance was 10 feet.

I want to be NEC-compliant and am very interested in doing it as properly as
I can (and hoping to leave the existing inside panel untouched, minus
transferring some of the existing panel's load - stove, dryer, sewerage
pump - to the new panel)

Thank you!



  #4   Report Post  
Mark or Sue
 
Posts: n/a
Default Electrical service question - old house, new addition - expert advice needed

"major domo" wrote in message
...
I hired an electrician to come out and give a consult since I wrote the
questions.
He suggested option 1 at first (200A inside panel for heater and addition,
60' away from outside disconnect)
After he left, I checked the ampacity of the wire needed to feed option 1
and was told I'd need 4/0 feeder wire (at $7.50 a foot!) to carry
potentially 200amps.


Yes, 4/0 for aluminum, 2/0 for copper. And you must have a 4th equipment
grounding wire that is #4 aluminum or #6 copper. Big ugly feeder.


After reading your analysis and calling the electrician back, he said I
could optionally run 2 wires (one dedicated to inside heater, one to a
100amp panel) instead of 1 wire to do both.
That way I could run 4/3 copper 60' through the attic directly to the
heater (heater only) and 2/3 copper 60' through the attic to a 100amp

panel
for the addition (lights, sockets, stove, dryer, sewerage pump) (instead

of
a 200amp panel as per option 1), and have an outside breaker for each
seperate circuit (total of 4 circuits - old inside panel, new inside

panel,
central air heater, outside compressor).
It intuitively seems to be a better solution to distribute the load over 2
wires instead of 1.


Its actually better cost wise for one large feeder. Safety wise it shouldn't
matter as you'll protect the wires with the proper size breaker.


I rechecked my old inside main, and there is indeed a 100amp single throw
double breaker for the stove. At least when I throw it, the stove is off,
but other lights are on. The stove consists of a separate oven and

rangetop.
Have no idea why the original homeowners installed a 100amp breaker, but
it's there. I'm guessing the wire coming from it is a #6.


Wow. I'd definitely fix that when you change your power. I've never seen a
range that would be allowed to be connected to a 100A circuit. Probably
would be wise to double check all wire sizes and the breakers protecting
them.


BTW, the new central air and electric heater is a Goodman 4 ton 13 SEER
conventional unit (not a heat pump)
According to option 2 (which is what I'm tending towards now), the heater
will have it's own dedicated circuit from the outside meter base and
breaker.
Should I also have an second inside breaker/disconnect for the heater at

the
heater location (which is right above the new panel, in the new attic)?


The heater must have a disconnect within sight of the heater. If your main
panel or feeder disconnect is within sight of the heater, then you're done.
If not, you'll need a disconnect box (but it doesn't have to have a fuse or
breaker). Same rules for the outside A/C.


I appreciate your mention of separating the ground and neutral busses on

the
subpanel.
I don't know if the exisiting inside panel is able to be ground and

netural
separated. I do know that most of the wires going through the exisiting
structure do not have a ground wire. It is also good to know that a

subpanel
can have a main breaker (that was a hard one to find an answer to). Home
Repo suggested that a subpanel without a main breaker (main lug?) had to

be
used if the distance was 10 feet.

I want to be NEC-compliant and am very interested in doing it as properly

as
I can (and hoping to leave the existing inside panel untouched, minus
transferring some of the existing panel's load - stove, dryer, sewerage
pump - to the new panel)


May want to visit here if you have more questions:
http://www.selfhelpforums.com/forums...974ba858930386
db5be7e2574a3e83

--
Mark
Kent, WA



  #5   Report Post  
Al
 
Posts: n/a
Default Electrical service question - old house, new addition - expert advice needed

Having a range on a 100 amp breaker could be dangerous. It shouldnt
be wired with #6, but it may feed a subpanel. In my house, i have
"pushmatics" and the 100 amp main panel has a split bus. On the
"always on (no main)side, there is a 30 for the clothes dryer, a 60
for cooking equipment, (my fryer, stove, oven, and rooftop exhaust
blower unit) then there is a 70, that feeds the bottom portion of the
panel. The lights and plugs come off that. There is a tap off the
bottom (protected by the 70)that goes to a *400* amp "QMQB" style
PANELBOARD, that covers all the basement stuff. The owner was an
electrician, and had a ""spare"" FPE QMQB board. Oh well... ( the
FPE is pro-tected by a 70 amp breaker, so i dont worry too much)
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