ECN Forum Forums Code Related Discussion NEC & other Code issues Location of Disconneting means of sub panel

Can someone help me out and find in the the NEC2005 where it talks about the location of a disconnect for a sub panel.

Its my unerstaning that you must have not more then 6 disconnecting means for a panel. Does this apply to a sub panel? If so its my undertanding its best to back feed the panel with a breaker and label that as the disconnecting means. OR you can install a fused dissconnect as long as it is "with in sight". Either way the disconneting means must be "with in sight".

I have found the following code referances:230.71 max number of disconnects, and also 230.91 location of OCD. Would these be the correct referances for my situation?

Thannk you as always

E

The 'disconnect' for a sub panel is the circuit breaker/fuses at the source of the feeder for said sub panel.

You must not exceed six (6) switches at the service entrance (excluding exemptions)
ie: a 'main' panel with six (6) switches/brkrs for the feeders/circuits sourced within that panel.

Yes, you can have a 'main' within (or adjacent) to the sub panel, but it is not required.

As long as the feeding panel, with the CB, it is with in sight that makes sence. But if the feeding panel is not with in sight. I think you must have a CB on the feeders feeding the sub panel.


E

HotLine1's right

There is no such requirement.

The only things that require a disconnect to be "in sight from " are transformers, motors, fixed heating equipment, storage batteries, tents and concessions, mobile homes, signs, and fixed appliances

i don't recall a definition of subpanel, methinks that's our own jargon.

that aside, there's much ado about where said 'subpanel' may be.

for instance a 'subpanel' can be withing the same structure, or in a satelitte structure

this becomes, imho, the point of definitional confusion

in the latter case,iirc, although it may be referred to as 'the barn subpanel' it will still fall under the auspices of the 'service entrance' doctrine within the nec...

~S~

So it is correct to say, it must have a single or no more then 6 means of disconnect in it. Or it must have a breaker back feeding the panel for a main.

E

If the load side panel is in the same structure it does NOT need a local disconnect. If it is in a separate structure there does need to be a disconnecting means in that second building. The 6 throw rule really only applies to "power panelboards". "Lighting and appliance panelboards" (more than 10% of breakers serving branch circuits) can have no more than 2 main breakers. 408.16(A)

Greg- look at 225.32 & 225.33

Hang on there guys...
The OP didn't say anything re: locations, multi-bldgs, etc.

Soko:
A little more detail/info please!!

unless you're tapping into a set of larger ampacity wires,or bus duct, your sub panel, won't require a breaker. The feeders will be protected by the breaker which feeds them.

naw, that's true Hotone, it's really a mixed code issue (i.e.- many relevant codes & definitional aspects) and we really haven't even muddied it up with the rule of 6 thing yet

iirc, some older handbooks showed 6 meters x 6 drops on a structure

and i'm sure one electrical historian could probably dig up a 6 fingered firechief , or other authority of stature in our murky past suggestive of incest in the nec....

it's not fair to mislead you with a yes/no here sokoservices, check out the relevant codes being forwarded, it's all very situational

safe to say, however, that adding a 'main breaker' to any feeder isn't a code violation (that i'm aware of) , and actually makes it all the more convienet for servicing


~S~

Electure- the only time you need a disconnect within sight of a xformer is when it is in a tunnel. I think.

George, I agree I was assuming ... one sub panel. If you had more panels you could have more disconnects up to six. I guess you could even have 6 "grouped" snap switches disconnecting one branch circuit. I was really just pointing out the "lighting and appliance panel" limit of two.

Sorry for any confusion.

iirc, the lighting & appliance panel codes have a substaintial '08 change

S(more fat for the fire)parky

Sokoservices also keeps referring to "back feed the panel" when I am assuming he means "feeding the sub-panel" since back feeding implies a switch between load side and line side and is generally used in lay context of installing generators and such.

"Back feeding" a breaker is simply when you delover power to the screw terminals, and power exits the breaker at the buss connections. That is, current flow is in the reverse of the usual direction.

This method is commonly used in "all in one" panels, where the 'back fed' breaker is the first, and only, means of service disconnect.

It's also used to provide a local disconnect to a 'sub panel,' or when the panel lacks any sort of lugs on the busses.

Sparky is right. I really haven't spent a lot of time with the 2008, (Fla is still 2005)
It looks like they have removed the whole "lighting and appliance" vs "power" distinction.
I haven't chewed over all the ramifications but it looks like I could have a MLO subpanel in the detached garage with 6 breakers and call that the disconnect.
Sorry for any confusion

One Disconnect is allowed for Each Supply. So 225.30,225.31,,225.32,225.33. All tie together.
So you need a Main for Each Supply.See 225.30 to see what Qualifies as a Supply.
Yoopersup