Two business ,side by side with a firewall separation. If there are main disconects located outside, Can a feeder pass through one structure to supply the other. sec #230.6 is about service conductors. what applies to feeder going through one building to serve another ?

There is nothing to prevent such an installation in the NEC.

The only rules I saw here in Mass is they wanted it sleeved and fire caulking applied.

Don't know of the rules where I am, but I know of one buinsess establishment where such a situation apparently is so.

I'm thinking of 230.3 and that is also regarding service conductors. I guess that's because Article 230 is titled "Services".

If there's only one service I don't know of an issue.

there are 2 services, one for each building. feeder is passing through building # 1 to supply building # 2

Again, I don't know of a restriction on feeders, only on service conductors.

Look at Service Conducors and Service Equipment in Article 100. If the conductors are after the service disconnect then they are feeders.

If they're not feeders then look at 230.3.

Wouldn't 225.31 apply as they are by code Two seperate Buildings.
If theres a Fire in one building the main would be shut down, Then firemen thinking there clear would start using water on live circuits.

MJ, very interesting. It seems that a literal interpretation of the Code would allow a building to have one service AND one feeder entering it. I am not sure if this is the intent however, it seems to be something that was overlooked. Article 225-30 limits to 1 feeder with exceptions and Article 230-2 allows only 1 service, again with exceptions.

Yoopersup is on the right track concerning shutting off power to the building. Definite safety considerations there, and not only to firemen, but electricians and maintenance personnel as well.

The 2005 Code allows a building to have extra feeders or services if "enhanced reliability" is a neccesity: 225-30(A)(6) and 230-2(A)(6)

The two mains are located outside, presumedly side by side. Firemen should notice both, and shut off power, then extinguish the fire.
Feeders after the main could run anywhere through the interior. If fire walls are penetrated, then they must be sealed and/or repaired, according to building code (as always).

Does common sense indicate we should maybe run building two's feeder outside the building? Maybe.
Do economic concerns indicate we should run SER, and keep it as short as we can (running through building one)? Maybe.
Either choice meets code.

Building code and the NEC define a building as a structure standing alone or separated by fire walls (not merely fire rated assemblies). Do not confuse the two.

Fire rated assemblies are not necessarily structural (but could be) and can include walls, ceilings, floors, and even roofs. they are intended to delay the spread of fire for a period of time to allow folks to exit the building safely, and the fire folks to extinguish the flames.

Fire walls are special fire rated assemblies that also will structurally support the building on either side of the wall even when there is a fire on the opposite side of the fire wall. An example is a masonry or concrete wall of appropriate thickness, with staggered nitches for the insertion of the beams and girders that hold the floors, ceilings and roof structure elements. If a fire should burn a girder completely through, the girder would fall into the inferno (due to special "fire cut" ends), but the fire wall would remain standing, and the building beyond would remain structurally sound.

Fire walls separate a single structure into buildings. Fire assemblies separate a building into fire or smoke areas.

Speaking as a firefighter I would say that the dangers to firefighters from live medium voltage circuits is often over stated. Test conducted with fire hose streams applied to high voltage lines demonstrated that even at utility distribution voltages the stream has to reach the conductors while it is still a continuous flow of water and before breaking over into spray and the stream must also be within a relatively short throw to be capable of conducting dangerous currents. Remember that the code is intended to provide for the "practical safeguarding of persons and property from hazards arising from the use of electricity." It is not practical to attempt to anticipate any and all abnormal conditions that could lead to additional hazard.
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Tom H