When to upgrade

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tonype

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Home had Federal Pacific panels - panels were just removed in anticipation to a sale (2 family home) - have yet to be approved by AHJ. New services are 50-amps per dwelling.

The home was built in 1971 and I guess had 50-amp services per dwelling originally (though that even seems to be "light" for that time frame).

Since 100-amps per dwelling is now minimum required (for new), is there a provision that allows lower levels of service to be replaced "in kind"?
 
Not for two family dwellings (230.79(D))

If it is new, it must meet code.
 
Since they've only changed the panels and have not upgraded the service the NJ rehab code would likely allow a 50 amp replacement.
 
infinity said:
Since they've only changed the panels and have not upgraded the service the NJ rehab code would likely allow a 50 amp replacement.
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Interesting subcode... Wish they had something like that a litle farther south..
 
infinity said:
Since they've only changed the panels and have not upgraded the service the NJ rehab code would likely allow a 50 amp replacement.
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Thats what I thought - tough on new buyer, since he wants to put in 3-ton AC units (along with air handlers) for each dwelliing.
 
Hv&Lv said:
Interesting subcode... Wish they had something like that a litle farther south..
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I agree it's actually a good idea on the part of the State to allow some variance from the current code to do things that will enhance safety. Replacing an obsolete FPE panel is a good example.

tonype said:
Thats what I thought - tough on new buyer, since he wants to put in 3-ton AC units (along with air handlers) for each dwelliing.
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The he can pay for a new service.
smile.gif
 
Feeder vs sec

Feeder vs sec

:?Just to continue the discussion.

Is it not the case that although NEC requires a minimum 100 amp service, the main panel need only be sized to accommodate the calculated load if it is not service equipment? So, if the service equipment has a disconnect then the panel inside the house is fed by a feeder.
 
Was just pondering this some more - does anyone know what the minimum requirements for a 2-family home were in 1971? Was it 50-amps per dwelling?; 60? or some other number?
 
This has been more recent topic. I believe the disconnecting means must be 100 amps. Nothing about minimum size of conductors or overcurrent devices. Now if you have a 100 amp breaker as the disconnecting means it is hard not to get away with less than 100 amp conductors.
 
kwired said:
This has been more recent topic. I believe the disconnecting means must be 100 amps. Nothing about minimum size of conductors or overcurrent devices. Now if you have a 100 amp breaker as the disconnecting means it is hard not to get away with less than 100 amp conductors.
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What about this?

230.42 Minimum Size and Rating.
(A) General. The ampacity of the service-entrance conductors before the application of any adjustment or correction factors shall not be less than either (A)(1) or (A)(2). Loads shall be determined in accordance with Part III, IV, or V of Article 220, as applicable. Ampacity shall be determined from 310.15. The maximum allowable current of busways shall be that value for which the busway has been listed or labeled.
(1) The sum of the noncontinuous loads plus 125 percent of continuous loads
(2) The sum of the noncontinuous load plus the continuous load if the service-entrance conductors terminate in an overcurrent device where both the overcurrent device and its assembly are listed for operation at 100 percent of their rating
(B) Specific Installations. In addition to the requirements of 230.42(A), the minimum ampacity for ungrounded conductors for specific installations shall not be less than the rating of the service disconnecting means specified in 230.79(A) through (D).
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Reading 230.80 Comined Rating of disconnects, "the size of the service-entrance conductors is required to be adequate for the computed load,and each individual serice disconnecting means to be large enough fot the individual load it supplies. So as long as the SE conductors are size to handle both dwellings and the conductors to each dwelling is sized right you dont need a 100amps to each.
 
I'm in one of the hottest, most humid parts of the country right now (far from Nevada) .... and the area typically has 1000 sq. ft., 3-bedroom, freestanding homes served by 2-ton air conditioners. Note that this is for homes with poor insulation, old windows, and little shade.

You say a '2-family home.' A duplex- meaning that there is a shared wall. I just can't see the place needing 3 tons of cooling per side. I do see the air conditioning needing some help in winter, if it is also being used as a 'heat pump'.

Likewise, a "3 ton" unit might need anywhere from 25 to 50 amps, depending on just how efficient it is.

Before we worry about what the code 'allows,' why don't we first find out what we really need?
 
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