NEC 2014 230.40 vs 230.71

[hhsting]

I have 8 multi occupancy in single story commercial building. I have incoming service into trough outside wall of the building. The trough has eight service disconnects grouped for eight different occupants in the building. No main breaker.

Based on NEC 2014 Section 230.40 exception number 1: “...If the number of service disconnect locations for any given classification does not exceed six, the requirement of 230.2(E) shall apply at each location. If the number of service disconnect locations exceeds six for any given supply classification, all service disconnect locations for all supply characteristics, together with any branch circuit or feeder supply sources, if applicable, shall be clearly described with suitable graphics or text...” I am allowed to have more than six service disconnects so as long as I can label.

However, NEC 2014 section 230.71(A) says max allowed is six.

1. What is the difference between two and why their is discrepancy?

2. Does this mean I am not allowed more than six service discos or I am allowed so as long as I can label them 230.40 exception 1 for above case?


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[charlie b]

The basic rule starts as, "one building, one service." Then, as an example, it says you can have a 208V service and a 480V service to the same building. Those are two possible "classifications" as used in 230.40. Next, 230.40 says, for example, you can run separate 208V services to Occupants 1 through 4, and you can also run separate 480V services to Occupants 5 through 8. Each of those 8 separate services can have up to six disconnects of its own. In my example, "the number of service disconnect locations for any given classification does not exceed six," because there are 4 such locations for the 208V classification of service, and 4 such locations for the 480V classification of service.

Your description appears to me to be a violation. You have only one classification (you didn't tell us the voltage), and you have one service to one location. That location is limited to six disconnects, unless you add a main breaker (or fused disconnect) upstream of the trough.

 

[hornetd]

The basic rule starts as, "one building, one service." Then, as an example, it says you can have a 208V service and a 480V service to the same building. Those are two possible "classifications" as used in 230.40. Next, 230.40 says, for example, you can run separate 208V services to Occupants 1 through 4, and you can also run separate 480V services to Occupants 5 through 8. Each of those 8 separate services can have up to six disconnects of its own. In my example, "the number of service disconnect locations for any given classification does not exceed six," because there are 4 such locations for the 208V classification of service, and 4 such locations for the 480V classification of service.

Your description appears to me to be a violation. You have only one classification (you didn't tell us the voltage), and you have one service to one location. That location is limited to six disconnects, unless you add a main breaker (or fused disconnect) upstream of the trough.

Please forgive my ignorance. I did a lot of oddball stuff when I was still working in the craft and I loved that it. But I would be the last one to say I've had broad experience in the light commercial market or any experience except for some control work in the industrial market. I did get to do a lot of Fire Alarm work in all sorts of premises though.

Just out of idle curiosity let me ask is there no such thing as unfused disconnect that is listed as SUSE?

--
Tom Horne

 

[charlie b]

Just out of idle curiosity let me ask is there no such thing as unfused disconnect that is listed as SUSE?

The relevant rule is 230.71. Each building must have a way of turning off all power. A building's main disconnecting means does not need to include overcurrent protection. So it is likely that there exists unfused disconnects that are listed as "Suitable for use as Service Entrance."

 

[hornetd]

The relevant rule is 230.71. Each building must have a way of turning off all power. A building's main disconnecting means does not need to include overcurrent protection. So it is likely that there exists unfused disconnects that are listed as "Suitable for use as Service Entrance."

So the remaining question is which one would cost the least. In the absence of available fault current above that of the individual breakers or switches in the six individual disconnects One could use an unfused switch or if there was some reason not to fuse the actual Service Disconnecting Means of the single switch one could resort to listed fuse shunts. As I said I do not have broad experience in this market. Hence my next question. How pricey are fuses in that range of sizes.

 

[packersparky]

I agree with Charlie. I would say it is not compliant as is. To use Exception No. 1 to 230.40, the service entrance conductors must be run to each occupancy. The way it is set up now that is not the case.

 

[electrofelon]

So the remaining question is which one would cost the least. In the absence of available fault current above that of the individual breakers or switches in the six individual disconnects One could use an unfused switch or if there was some reason not to fuse the actual Service Disconnecting Means of the single switch one could resort to listed fuse shunts. As I said I do not have broad experience in this market. Hence my next question. How pricey are fuses in that range of sizes.

I am not quite sure what you are getting at or proposing and how it relates to the OP. Could you elaborate a bit? Note that the over current protection must be "immediately adjacent to" the service disconnect.

 

[don_resqcapt19]

The code language permits each set of service entrance conductors to have up to 6 means of disconnect. There is no requirement to have six or less disconnects that will disconnect the whole building. The only issue is the undefined term of "grouped". How far away does one set of disconnects have to be from another set to not be "grouped"?

 

[hornetd]

I am not quite sure what you are getting at or proposing and how it relates to the OP. Could you elaborate a bit? Note that the over current protection must be "immediately adjacent to" the service disconnect.

I'm sorry if I was unclear. I was just trying to visualize how one could make up one of these multi-switch services for say a 14 unit garden apartment house and still have a single Service Disconnecting Means. I was trying to get an idea of how to avoid the cost of the large fuses which I remember from a decade ago as being dammed pricey. If I ended up using a fused switch because it costs less than an unfused switch because of the amount of demand for each type I opined that I could use fuse shunts.

What you have now done is to blow that hole idea out of the water by saying that the overcurrent protection has to be immediately adjacent to the Service Disconnecting Means. I take it by "immediately adjacent" that you mean the fuse holders would have to come off of the load terminals of the switch itself rather than in an adjacent meter stack with 9 meter mains in it.

How do those of you who have done a few of these actually build them. Is the only compliant approach to have a single breaker or fuse set ahead of the whole Meter Stack? Just for aiding my education let me ask if I installed 20 space Main Lug Only panel right off the bottom of the Unfused or shunted fused switch? Do you think that a competent inspector would accept that as having the Over Current Protection "immediately adjacent?" If you don't want to speculate on the decision of some unknown inspector would you yourself accept it if you were the inspector? I'm retired so if you are wrong it is only theoretical anyway. I'm done working several stories in the air on open decks in February thank God.

I can honestly say that I have attended more second alarm fires in those 14 unit garden apartments than I have wired. I can only remember having been on the crew for 2 of them and in both case I was functioning as a Journeyman and not the Foreman. Back in the day; say 30 years ago; this corner of the county was it's "Fire Alley." We would attend a second alarm fire a month in one of those 14 unit garden apartments and a well developed room and contents fire nearly weekly. Now that I'm aged out of the active Fire Service the serious fires have spread out across the county. I don't think we are having a lot less of them they are just further apart.

--
Tom Horne

 

[hhsting]

I agree with Charlie. I would say it is not compliant as is. To use Exception No. 1 to 230.40, the service entrance conductors must be run to each occupancy. The way it is set up now that is not the case.

Each set of service entrance conductors do run to each occupancy. See attached sketch

 

[hhsting]

The basic rule starts as, "one building, one service." Then, as an example, it says you can have a 208V service and a 480V service to the same building. Those are two possible "classifications" as used in 230.40. Next, 230.40 says, for example, you can run separate 208V services to Occupants 1 through 4, and you can also run separate 480V services to Occupants 5 through 8. Each of those 8 separate services can have up to six disconnects of its own. In my example, "the number of service disconnect locations for any given classification does not exceed six," because there are 4 such locations for the 208V classification of service, and 4 such locations for the 480V classification of service.

Your description appears to me to be a violation. You have only one classification (you didn't tell us the voltage), and you have one service to one location. That location is limited to six disconnects, unless you add a main breaker (or fused disconnect) upstream of the trough.

I must not be getting something. 230.40 exception no. 1 says for any given classification of service. Furthermore handbook 2014 230.40 exception no. 1 explains about 208/120V single service with 8 sets of service entrance conductors one set going to each occupancy and apparently says labeling is okay does not mention main breaker blue commentary.

How can you say for different classification of services code only says any classification of service singular meaning I can have one service voltage phase, do 8 sets of service entrance conductors each one set going to 8 tenants without having providing main disconnect and just label them per 240.30 exception no. 1 no?

 

[electrofelon]

Each set of service entrance conductors do run to each occupancy. See attached sketch

No false. You have service disconnects all grouped together and FEEDERS running to each occupancy.

 

[electrofelon]

I'm sorry if I was unclear. I was just trying to visualize how one could make up one of these multi-switch services for say a 14 unit garden apartment house and still have a single Service Disconnecting Means. I was trying to get an idea of how to avoid the cost of the large fuses which I remember from a decade ago as being dammed pricey. If I ended up using a fused switch because it costs less than an unfused switch because of the amount of demand for each type I opined that I could use fuse shunts.

What you have now done is to blow that hole idea out of the water by saying that the overcurrent protection has to be immediately adjacent to the Service Disconnecting Means. I take it by "immediately adjacent" that you mean the fuse holders would have to come off of the load terminals of the switch itself rather than in an adjacent meter stack with 9 meter mains in it.

How do those of you who have done a few of these actually build them. Is the only compliant approach to have a single breaker or fuse set ahead of the whole Meter Stack? Just for aiding my education let me ask if I installed 20 space Main Lug Only panel right off the bottom of the Unfused or shunted fused switch? Do you think that a competent inspector would accept that as having the Over Current Protection "immediately adjacent?" If you don't want to speculate on the decision of some unknown inspector would you yourself accept it if you were the inspector? I'm retired so if you are wrong it is only theoretical anyway. I'm done working several stories in the air on open decks in February thank God.

I can honestly say that I have attended more second alarm fires in those 14 unit garden apartments than I have wired. I can only remember having been on the crew for 2 of them and in both case I was functioning as a Journeyman and not the Foreman. Back in the day; say 30 years ago; this corner of the county was it's "Fire Alley." We would attend a second alarm fire a month in one of those 14 unit garden apartments and a well developed room and contents fire nearly weekly. Now that I'm aged out of the active Fire Service the serious fires have spread out across the county. I don't think we are having a lot less of them they are just further apart.

--
Tom Horne

Tom,

It has been a while since I compared the price of a larger sized fused safety switch vs a circuit breaker + enclosure, but I do not recall there being a drastic difference in price. I think the safety switches are physically larger which may or not be an issue. I installed a 1000A fused safety switch once and it is definitely a big boy.

IMO "immediately adjacent thereto" means within a foot or two with no other equipment in between. BTW 230.91 is where that wording can be found.

I would just buy the meter stacks and service disconnect as one assembly (it would be modular of course).

What are "fuse shunts" and could you explain a little more how they would be used?

 

[hhsting]

No false. You have service disconnects all grouped together and FEEDERS running to each occupancy.

Electrofelon my buddy thank you for your help.

Also thanks to for everyone else here for helping me as well and responding so far.


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[hornetd]

Tom,

It has been a while since I compared the price of a larger sized fused safety switch vs a circuit breaker + enclosure, but I do not recall there being a drastic difference in price. I think the safety switches are physically larger which may or not be an issue. I installed a 1000A fused safety switch once and it is definitely a big boy.

IMO "immediately adjacent thereto" means within a foot or two with no other equipment in between. BTW 230.91 is where that wording can be found.

I would just buy the meter stacks and service disconnect as one assembly (it would be modular of course).

What are "fuse shunts" and could you explain a little more how they would be used?

Fuse shunts are brass or copper tubes; like the short pieces of scrap copper pipe some of us may have used at one time or another in the new meter socket while you are waiting for the Power Utility to deign to put in an appearance and cut your new service over to your new Service Entry Conductors; that have laboratory listing labels on them to show that they can carry the maximum current that would have gone through the largest fuse that would have fit in that size fuse holder. They are used to convert a Fused Disconnect to a unfused one. Back in the day they were often used to make a disconnecting means for a load by using a fused pull out and fuse shunts. That was done because you needed a servicing disconnect at the equipment but you didn't want the machine to be automatically shut down by an OCPD located there.

One example was the servicing cut outs for the pump motors which had been converted to automatic control. The condition of the load side of the OCPD in a panel was now to be monitored at the panel in which it is installed because they was more practically monitored at that one location. Individual branch circuits had been run to the motors and the fused pullouts that were previously tapped off a large feeder were now to remain as servicing switches. Pull the old fuses, install listed fuse shunts, and call it a day.

Second example. Called in to add a circuit to an existing panel and find on arrival that the panel cabinet was built from scratch by the original electrician at the dawn of the electrical era. Since the initial power supply to that building had been from 600 volt trolley traction power Double Pole porcelain base Knife Switches are the switches for each branch circuit. They are installed so that the knives will always be hot and there are fuses in both of the conductors of each branch circuit. The fuse holders are Edison sockets. Be careful with the carefully cut to fit asbestos board with rather ragged cut edges which line the cabinet. The panel is built onto the back wall of the cabinet with porcelain based switches, sockets and so fourth. Equipment Grounding Conductors? No way! The supplied circuits are all knob and tube with the thickest walled porcelain tube and the largest insulator knobs I've ever seen used for that work.

Step one; get enough 30 ampere Edison base fuses for all of the neutrals from the truck and install them in all of the neutral fuse holders. In spite of the oversized wires; #10 AWG; fuse all of the energized conductors at 15 amperes.
Step two; overnight order listed Edison socket fuse shunts. [You new they had to be in here someplace]
Step Three; Pitch a new panel located at the newer service equipment in the basement to the buildings owners and offer to give $100 dollars off for the old panel.
Step four; Install listed fuse shunts in neutral fuse sockets and await directors decision on the replacement panel.
Step five; Install the new copier circuit that they had originally called me for by fishing MC cable from the somewhat newer service equipment in the basement.

--
Tom Horne