Service Entrance Condutors and number of ing meansdiscon

[Dvigeant]

My college and I are having a discussion about Articles 230.71 and 230.40 of NEC and their interpretation.

We have one utility meter on the mounted on an H-frame next to a three phase utility owned transformer. From the transformer secondary taps there are 16 sets of conductors connecting to two bus duct (8 conductors each). The bus duct goes through a wall into two separate 3,000A switchboards (one bus duct each). Each switchboard has 6 main circuit breakers. The switchboards are mounted end to end in the same room. My questions are as follows:

1. Do we have one or two sets of service entrance conductors per article 230.40?
2. Is this set-up a violation of Article 230.71, A? i.e. More than 6 service disconnecting means.
3. What is meant by ?separate loads? in Exception No. 2 of Article 230.40? Does this mean separate occupancies?

 

[Dvigeant]

Re: Service Entrance Condutors and number of ing meansdiscon

I have reread the code for a forth time and I just noticed the Exception No. 2 in 230.40 was not included in 230.71. However I will still be interested in your replys

 

[ron]

Re: Service Entrance Condutors and number of ing meansdiscon

230.40 ex 2 would indicate that you have two sets of service entrance conductors (one for each service equipment enclosure).
Seems that they are in violation of 230.71.
230.40 ex 2 the term "separate loads" IMO just means separate stuff, not separate occupancies.

[ March 25, 2005, 09:17 AM: Message edited by: ron ]

 

[charlie]

Re: Service Entrance Condutors and number of ing meansdiscon

230.2(C)(1) grants the second service drop and you have one set of service entrance conductors for each service which makes you in compliance with 230.40 without the use of any exceptions. Additionally, you have only six service disconnecting means per service grouped in any one location so you are square with 230.71(A).

Other than "it seems to be wrong", there are no problems with the installation.

 

[mc5w]

Re: Service Entrance Condutors and number of ing meansdiscon

If your capacity need is more than 2,000 amps then you are allowed to have 2 or more services to reach the aggragate capacity. One of the telephone central offices near the former World Trade Center in New York City has close to a DOZEN 4,000 amp 480 volt services! Makes the meter spin really good.

 

[Dvigeant]

Re: Service Entrance Condutors and number of ing meansdiscon

[230.2(C)(1) grants the second service drop and you have one set of service entrance conductors for each service which makes you in compliance with 230.40 without the use of any exceptions. Additionally, you have only six service disconnecting means per service grouped in any one location so you are square with 230.71(A).] [/QUOTE]

To give you a better view, this building has multiple transformer locations (services) per Article 230.2(C)(1). They have a 750KVA transformer feeding a 4000A switchboard, Three single phase 500KVA transformer feeding a 3000A switchboard, three single phase transformers feeding two electrical fire pumps and (the one in question) a 3750KVA transformer feeding two 3000A switchbaords.

Based on your comments you believe that this facility has five services. based on my interpretation of the code I believe this facility has four services.

The service in question, I interpret that it is one service with two sets of service entrance conductors which would fall under exception No. 2 of 230.40. However the installation is in violation with 230.71(A).

If we go by your interpretation, would be still in violation in which we have more then six service disconnecting means in one location? Per Article 230.71(A)

 

[Dvigeant]

Re: Service Entrance Condutors and number of ing meansdiscon

On a side note. The conductors from the 3750KVA transformer and the bus are approximately 10' long. The bus duct is approximately 10' long. the transformer is approxiamtely 12' from the outside of the building.