On branch circuits the size of the wire and type of circuit determines the
breaker size but what determines the size of the main or combination of
mains? Can it be as large as the panel is rated for or must it match the
size of the utility's drop?

We have an old panel with two mains, one is a double 50A feeding the rest
of the panel. The other is a double 30A feeding the dryer outlet directly.
The town now mandates 100A and I think homes get inspected when sold.
Rather than replace the whole panel I could replace main #1 with a double
70A (if available) OR maybe better would be to replace main #2 with a
double 50A (or higher) and have it feed a small subpanel in which I would
put a double 30A for the dryer and maybe throw in a few others as well.
That's within the rating of the main panel but not sure about the utility
drop.

On May 7, 12:29�pm, Big Giant Head
wrote:
On branch circuits the size of the wire and type of circuit determines the
breaker size but what determines the size of the main or combination of
mains? *Can it be as large as the panel is rated for or must it match the
size of the utility's drop?

We have an old panel with two mains, one is a double 50A feeding the rest
of the panel. *The other is a double 30A feeding the dryer outlet directly. *
The town now mandates 100A and I think homes get inspected when sold. *
Rather than replace the whole panel I could replace main #1 with a double
70A (if available) OR maybe better would be to replace main #2 with a
double 50A (or higher) and have it feed a small subpanel in which I would
put a double 30A for the dryer and maybe throw in a few others as well. *
That's within the rating of the main panel but not sure about the utility
drop.

Main breaker must match main service drop and meter can and panel.

With such low ratings how is the physical condition of your drop?

I have a friend epoxying his drop to keep the outer jacket together

go with 200 amps its well worth just a few bucks extra

On May 7, 12:37?pm, Meat Plow wrote:
On Mon, 07 May 2007 16:29:22 +0000, Big Giant Head wrote:
The town now mandates 100A and I think homes get inspected when sold.

cha ching

Even if town didnt mandate it buyers get scared off by nearly
everything today.

The DIY people here wouldnt agree, heck I like fixing stuff

90% of home buyers today want a move in condition no work, if you have
issues all thats left is the 10% of buyers looking for a bargain:
( worse most home buyers spend every dime they can having no money for
even necessary repairs

Big Giant Head wrote:
On branch circuits the size of the wire and type of circuit determines the
breaker size but what determines the size of the main or combination of
mains? Can it be as large as the panel is rated for or must it match the
size of the utility's drop?

We have an old panel with two mains, one is a double 50A feeding the rest
of the panel. The other is a double 30A feeding the dryer outlet directly.
The town now mandates 100A and I think homes get inspected when sold.
Rather than replace the whole panel I could replace main #1 with a double
70A (if available) OR maybe better would be to replace main #2 with a
double 50A (or higher) and have it feed a small subpanel in which I would
put a double 30A for the dryer and maybe throw in a few others as well.
That's within the rating of the main panel but not sure about the utility
drop.



The maximum size mains are determined by the box rating, or the size of
the service conductors, or the rating of the meter, whichever of these
is smallest (very rarely is it the meter.)

The 100A minimum requirement shouldn't apply to you *if* an electrician
does a load analysis and your service is large enough (look up the terms
"ex post facto law" and "grandfathered")

Bob

The 100A minimum requirement shouldn't apply to you *if* an electrician
does a load analysis and your service is large enough (look up the terms
"ex post facto law" and "grandfathered")

Bob

In most areas minimum upgrade standards exist. You can live with a 30
amp servicve but change ANYTHING and you must upgrade.

I'll have to check around to see what is actually being enforced. Just
going by what I saw in the paper. No move is in the works yet; just want
get my ducks in a row. For now I'll concentrate on getting rid of other
code violations such as the A/C condensor's cutoff box is connected by a
short conduit run over to the meter box. That's gotta be a major one,
running the wires carrying post-breaker power past the pre-breaker power.

Also our town of maybe 24,000 believes it knows more about these things
than the NEC so it adopts the NEC minus the chapter on NM so better replace
or conceal any Romex or UF.

"Big Giant Head" wrote in message
. 125.201...
On branch circuits the size of the wire and type of circuit determines the
breaker size but what determines the size of the main or combination of
mains? Can it be as large as the panel is rated for or must it match the
size of the utility's drop?

We have an old panel with two mains, one is a double 50A feeding the rest
of the panel. The other is a double 30A feeding the dryer outlet
directly.
The town now mandates 100A and I think homes get inspected when sold.
Rather than replace the whole panel I could replace main #1 with a double
70A (if available) OR maybe better would be to replace main #2 with a
double 50A (or higher) and have it feed a small subpanel in which I would
put a double 30A for the dryer and maybe throw in a few others as well.
That's within the rating of the main panel but not sure about the utility
drop.

It sounds as though you have an old split bus panel. No main was needed for
the entire panel, but only for the lower section due to some archaic six
circuit code exception which saved the original installer the cost of a main
breaker.

It's possible that your service already is 100 amp. You can determine this
by the wire size of the service. Assuming other things are in good
condition you may be able to get away with just replacing the panel. The
grounding electrode system will need to be updated as well.

Do not replace the existing breakers with a larger size. Most likely the
wire will not be rated for the larger size.

On May 7, 4:24�pm, "John Grabowski" wrote:
"Big Giant Head" wrote in messagenews:Xns992974D19E174bigxgiantxheadSPAMBL@2 07.217.125.201...

On branch circuits the size of the wire and type of circuit determines the
breaker size but what determines the size of the main or combination of
mains? *Can it be as large as the panel is rated for or must it match the
size of the utility's drop?

We have an old panel with two mains, one is a double 50A feeding the rest
of the panel. *The other is a double 30A feeding the dryer outlet
directly.
The town now mandates 100A and I think homes get inspected when sold.
Rather than replace the whole panel I could replace main #1 with a double
70A (if available) OR maybe better would be to replace main #2 with a
double 50A (or higher) and have it feed a small subpanel in which I would
put a double 30A for the dryer and maybe throw in a few others as well.
That's within the rating of the main panel but not sure about the utility
drop.

It sounds as though you have an old split bus panel. *No main was needed for
the entire panel, but only for the lower section due to some archaic six
circuit code exception which saved the original installer the cost of a main
breaker.

It's possible that your service already is 100 amp. *You can determine this
by the wire size of the service. *Assuming other things are in good
condition you may be able to get away with just replacing the panel. *The
grounding electrode system will need to be updated as well.

Do not replace the existing breakers with a larger size. *Most likely the
wire will not be rated for the larger size.

what condition is the existing drop and amp capacity of meter can?

The size of your service is determined by the service entrance conductors,
and if you have a single service disconnect, it would correspond to the size
of the entrance conductors as well. The "drop" is generally owned by the
utility company and doesn't conform to NEC standards. When you have multiple
service disconnects, the amperage of the total of the disconnects is not
required to equal the ampacity of the entrance conductors. As John Grabowsky
said, you probably have a 100 amp service already, and may be able to just
replace the panel and update the grounding electrode system




"Big Giant Head" wrote in message
. 125.201...
On branch circuits the size of the wire and type of circuit determines the
breaker size but what determines the size of the main or combination of
mains? Can it be as large as the panel is rated for or must it match the
size of the utility's drop?

We have an old panel with two mains, one is a double 50A feeding the rest
of the panel. The other is a double 30A feeding the dryer outlet
directly.
The town now mandates 100A and I think homes get inspected when sold.
Rather than replace the whole panel I could replace main #1 with a double
70A (if available) OR maybe better would be to replace main #2 with a
double 50A (or higher) and have it feed a small subpanel in which I would
put a double 30A for the dryer and maybe throw in a few others as well.
That's within the rating of the main panel but not sure about the utility
drop.

wrote in message
ups.com...


go with 200 amps its well worth just a few bucks extra


As another poster noted, the main panel breaker is sized to the drop from
the power company. IF the drop supports 200 amps then, yes, you might as
well spring for the larger panel. You never know when circumstances might
cause your unit to draw over 100 amps.

"John Gilmer" wrote in message
...

wrote in message
ups.com...


go with 200 amps its well worth just a few bucks extra


As another poster noted, the main panel breaker is sized to the drop from
the power company. IF the drop supports 200 amps then, yes, you might as
well spring for the larger panel. You never know when circumstances
might
cause your unit to draw over 100 amps.


How would you know if the drop was sized for 200A?

According to Eigenvector :

"John Gilmer" wrote in message
...

As another poster noted, the main panel breaker is sized to the drop from
the power company. IF the drop supports 200 amps then, yes, you might as
well spring for the larger panel. You never know when circumstances
might
cause your unit to draw over 100 amps.

How would you know if the drop was sized for 200A?

Ask the power company. But an electrician can probably give
a reliable answer.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.