400A service w/ two 200A panels

[iwire]

I mean that the NEC does not require the service conductors suppling multiple service disconnects to be rated what the over current protection adds up to.

I do not have my book here but to the best of my recollection this can be found in 230.90(A) Exception.

 

[tryinghard]

I mean that the NEC does not require the service conductors suppling multiple service disconnects to be rated what the over current protection adds up to.

I do not have my book here but to the best of my recollection this can be found in 230.90(A) Exception.

I believe these conductors sized per calc even with one disconnect. (230.42 - if it is service - and 225.5, & 215.2 - feeders.)

 

[iwire]

I believe these conductors sized per calc even with one disconnect. (230.42 - if it is service - and 225.5, & 215.2 - feeders.)

No not the same.

With a feeder or a service with one service disconnecting means no matter the calculated load the rating of the conductors must exceed the rating of the over current protection (other then 240.4(B))

With a service that has multiple service disconnecting means the over current protection can far exceed the rating of the conductors.

 

[augie47]

which takes us back to square 1. If the E/C had calculated the load and presented it both the meter socket and the riser might be compliant....and ivsenroute's day would have gone lot better

 

[tryinghard]

No not the same.

With a feeder or a service with one service disconnecting means no matter the calculated load the rating of the conductors must exceed the rating of the over current protection (other then 240.4(B))

With a service that has multiple service disconnecting means the over current protection can far exceed the rating of the conductors.

So 230.90(A) Exception No. 3 allows the service conductors to be exceeded by the sum of the overcurrent protection as long as the conductor rating is compatible for the calculated load.

 

[iwire]

So 230.90(A) Exception No. 3 allows the service conductors to be exceeded by the sum of the overcurrent protection as long as the conductor rating is compatible for the calculated load.

Exactly and it is quite common.:smile:

I used to work at one factory with a 1200 amp service that was made up of six breakers totaling over 3000 amps. This was how the building was built in the 1990s and is code legal. It is up to future ECs to make sure the 1200 amps of service conductors are not overloaded.

Now as far as the OP, if the EC can show the calculated load is below the rating of the conductors they are good to go ........ as soon as the meter socket is replaced.

 

[tryinghard]

Exactly and it is quite common.:smile:

I used to work at one factory with a 1200 amp service that was made up of six breakers totaling over 3000 amps. This was how the building was built in the 1990s and is code legal. It is up to future ECs to make sure the 1200 amps of service conductors are not overloaded.

Now as far as the OP, if the EC can show the calculated load is below the rating of the conductors they are good to go ........ as soon as the meter socket is replaced.

I have applied this many times myself.

But I thought even with one service disconnect the service conductors are sized by the calc?d load and not the equipment OCPD.

 

[iwire]

But I thought even with one service disconnect the service conductors are sized by the Calv?d load and not the equipment OCPD.

With a single the condutors must meet or excced the OCPD (Other than what 240.4(B) allows)

 

[tryinghard]

With a single the condutors must meet or excced the OCPD (Other than what 240.4(B) allows)

Often I see these smaller? Furnished and installed by utilities.

 

[Pierre C Belarge]

So 230.90(A) Exception No. 3 allows the service conductors to be exceeded by the sum of the overcurrent protection as long as the conductor rating is compatible for the calculated load.

With a single the condutors must meet or excced the OCPD (Other than what 240.4(B) allows)

The conductor for a single service overcurrent means is not calculated by load, it is as per the size of the overcurrent device.

MULTIPLE disconnect provides some relief (as it should), the conductors are sized on the calculated load.

This has been mentioned, yet I see much discrepency with these two code sections in the field. I find that most are not familiar with 230.90 EX#3.


All the contractor needs to do is a calculation, and pray that it is below 200A.

 

[iwire]

Often I see these smaller? Furnished and installed by utilities.

You lost me:-?, "Furnished and installed by utilities" means they are not subject to the NEC.

 

[Dennis Alwon]

You lost me:-?, "Furnished and installed by utilities" means they are not subject to the NEC.

I think he was trying to say that how can the riser or the service later comply with section 230. 90(A) if we have no control over the utility wire. Granted they are not within the confines of the NEC but the section seems to demand it.

 

[iwire]

I think he was trying to say that how can the riser or the service later comply with section 230. 90(A) if we have no control over the utility wire. Granted they are not within the confines of the NEC but the section seems to demand it.

???

Not trying to be jerk here I just have no idea what you are trying to tell me. :smile:

 

[Dennis Alwon]

???

Not trying to be jerk here I just have no idea what you are trying to tell me. :smile:

That's because I don't know what I am talking about.:wink:

The question is where does the service conductors begin? If the utility supplies the wire in the riser is it still service conductors? If it is then 230.90(A) excep. 3 states

Exception No. 3: Two to six circuit breakers or sets of fuses shall be permitted as the overcurrent device to provide the overload protection. The sum of the ratings of the circuit breakers or fuses shall be permitted to exceed the ampacity of the service conductors, provided the calculated load does not exceed the ampacity of the service conductors.

We have no control over that but are we still required to comply if 230.90(A) says so.

Is that clearer?

 

[ivsenroute]

UPDATE:

The owner of the building went to a local supply house and told them what he was doing and this is the result. He went to another supplier to get the correct materials for the job and tried to get a refund but was told no, even though they gave him the wrong materials. Sad part is that he hired a professional electrician to do the install who did not catch these issues.

Anyway, corrections were made, copper and a new meter base by Milbank and all is ok.

 

[tryinghard]

You lost me:-?, "Furnished and installed by utilities" means they are not subject to the NEC.

No in many cases, I mean the utility literally furnishes and installs the service conductors regardless of what they are bound by and these conductors appear smaller than what 310.15 would qualify.