ECN Electrical Forum
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Are you allowed to install a sub panel in an attic?

How about a service panel?

As long as you meet space and accessability requirements

I see them all the time around here, especially with multiple HVAC system zones. 100A sub panel to feed two heating sections in heat pump installations is fairly common in larger homes to feed backup heat.

I consider such an installation no different that the requirement to have a disconnect for the equipment anyway. Isn't a disconnect essentially the same thing as a sub-panel for the most part? In the instances that I encounter, this is just a case of these disconnects being contained within a single enclosure.

How do they get around 110.26?

If this is just a disconnect and the overcurrent protection for the branch circuit is in a properly serviceable location it is winked at but if this is the panelboard at the load end of a feeder or a tap I would really have to hear a story if I could not see 110.26(A) (1) through (3) satisfied.

There is always a nagging inconsistency in how we enforce 110.26(A). I have seen inspectors who are pedantic about the outside disconnect clearances for an HVAC condenser and then have no problems with the air handler disco stuffed in the corner of the closet with the air handler. I have seen some that you needed a skinny arm to even reach.

Greg, the ones I have encountered are for air handlers with backup heat are 240V only, so there is no requirement for a neutral. The ones I've seen are 4-circuit panels with 100 amp MLO panels to house two 2-pole breakers. They are all over the place around here. I should have clarified that there are no vacant pole spaces to allow "Harry Homeowner" to add a breaker for a ceiling fan.

Nevertheless, they still are technically sub-panels.

Don't make me go there........

I have see the subpanels in the attic but service panels once a while not very often due the POCO regulations plus local insepctors may have issue with nonOCPD'ed service entrance conductors in the attic space.

BTW Wisconsin say unfused service condutors are limited to 1.5 meter {5 feet} max

France - rather have all it outside much as possible but only allowed indoor short as possible

Unless you have main disconnection outdoor then after that it pretty much unlimited.

Merci,Marc

I would think ambient temps could lead to breakers tripping

Harold:
I've come accross a few recently, only issue I had (As Rewire said) was ambient temps. That was addressed via adequate ventilation, installed by HVAC contractor.

As to a service panel being in the attic, as long as unprotected conductors are addressed, I see no issue.

We put them in unfinished basements so why not an unfinished attic,I think a permenate stair would be required.

I guess I have just never seen an attic with 6'6" of headroom for the required 36x30 working space.
Since NFPA seems OK with a panel stuffed with AFCI/GFCIs in an un-airconditioned garage they must not see heat as being an issue. (in spite of most MCCBs being rated at 40C)