heater attic

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jeffhood

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An existing home has an electric heating unit in the attic,with one 2 pole 100 amp breaker
integral to the unit.This unit must be replaced . The new unit has two 2 - pole 60 amp breakers integral to the unit.The existing wire type feeding the old heater was xhhw size # 4.Can a breaker box be set in the attic and the two 60 amp subdivided loads be fed from this wire or must the new unit be fed from main panel with individual branch circuits?
 
Re: heater attic

You can use the conductors from the main panel to the attic as a feeder to a new breaker panel for the two 60 amp breakers. But that feeder (#4 XHHW) is only good for 85 amps. What is the load from the new heater? If the load is over 85 amps, then you need a new feeder that is sized for the load.
 
Re: heater attic

In response to the heater the loads are divided into two 48 loads.Also i was told from another electrician that an inspector told him that he could not put a panel in the attic.Does 422.11-f1 apply or 422-12?
 
Re: heater attic

Because this unit will be installed in an attic, shouldn't the feeder have the correction factors on table 310.16 applied also? Even with the load subdivided at 48 amps, shouldn't we need to know the total KW ratting of the unit and size the feeder using that? I have never installed anything like this so be easy on my apprentice questions :D :D :D

[ December 08, 2005, 03:01 PM: Message edited by: kevinware ]
 
Re: heater attic

1st look at the manufacturers data plate min. ampacity and max breaker size,That will tell you if the proper wire is installed and what size ocpd must be used.With #4 you should be ok.
Now I have never heard a job fail for using a sub panel in an attic as a serv disc..As long as all #`s work what is the violation ?
 
Re: heater attic

i agree with the panel not being an issue as far as the code is concerned, however reputable source said that a particular city would not allow it seems odd? :eek:
 
Re: heater attic

I was looking for a reason to fail it, but then stumbled across this:

240.24(A)(4) For overcurrent devices adjacent to utilization equipment that they supply, access shall be permitted to be by portable means.
Click to expand...
240.24(D) may be an issue, however. What about the insulation in the attic? Also, do you have working space about the panel? (Then again, it could be argued that the panel is solely for one piece of utilization equipment, so there's not much call for working on it energized.)

What are the nameplate ratings on the unit you're installing?
 
Re: heater attic

Can the unit be set up for one circuit alot of the units I do with 2 60amp breakers have the brakers tide together with one set of lugs. the lugs can be removed for 2 circuit feed. the unit shuld list that it can be 1 or 2 circuit feed.
 
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