Main Service Switch

[Alwayslearningelec]

So the main service is in building 280. They are running feeders to building 101. Is the xfrmr and switch is building 101 considered another service?

I ask because they are asking me to power the fire alarm FACP from line side of MAIN SERVICE switch. If that MIAN SERVICE SWITCH is considered the one in building 280 and not 101 that is a HUGE difference. Thanks

 

[infinity]

I don't see a service anywhere on your drawing.

 

[Alwayslearningelec]

It not showing but it's in building 280

 

[infinity]

It not showing but it's in building 280

Correct, so it's not relevant to building 101 because building 101 is fed by a feeder.

 

[Alwayslearningelec]

But if fire alarm FACP in building 101 is saying to feed from main service switch it might have to be fed all the way from building 280?

 

[Strathead]

That is a stupid statement and a stupid requirement. You need to RFI it more respectfully than I just put it. It is technically impossible to put it on the line side of the main service switch. You would have to have a service disconnect for the fire alarm branch circuit regardless of the voltage so it would NEVER be on the line side of the service switch.

To answer your specific question, building 101 is fed from a separately derived system, not a service.

 

[infinity]

But if fire alarm FACP in building 101 is saying to feed from main service switch it might have to be fed all the way from building 280?

Is there any code requirement to supply the FA ahead of a service located in a different building? I doubt it, in fact there's probably some code that prohibits it. As Strat stated ask the person who said "they are asking me to power the fire alarm FACP from line side of MAIN SERVICE switch." My guess is that they didn't realize that this building is fed by a feeder.

 

[jim dungar]

Sounds like industry slang again.
Someone is calling the "main" for Bldg 101 a Service even though us electricical people know better.

Just RFI itx as as

 

[infinity]

Sounds like industry slang again.
Someone is calling the "main" for Bldg 101 a Service even though us electricical people know better.

Just RFI itx as as

I agree nothing a quick RFI cannot fix. While he's at it the secondary conductors from the transformer in building 280 are too small for 400 amps.

 

[Alwayslearningelec]

Is there any code requirement to supply the FA ahead of a service located in a different building? I doubt it, in fact there's probably some code that prohibits it. As Strat stated ask the person who said "they are asking me to power the fire alarm FACP from line side of MAIN SERVICE switch." My guess is that they didn't realize that this building is fed by a feeder.

Thanks. You say by a "feeder". Do you use that term specifically when covo is about service because of the "wires" and what they are referred to?

 

[Alwayslearningelec]

I agree nothing a quick RFI cannot fix. While he's at it the secondary conductors from the transformer in building 280 are too small for 400 amps.

Why are two sets 400A too small?

 

[don_resqcapt19]

Thanks. You say by a "feeder". Do you use that term specifically when covo is about service because of the "wires" and what they are referred to?

The wires from the service point to the service disconnect are service conductors. All conductors on the load side of the service disconnect are feeders or branch circuit conductors.

 

[infinity]

Thanks. You say by a "feeder". Do you use that term specifically when covo is about service because of the "wires" and what they are referred to?

That's the actual definition of the conductors feeding building 101. By definition there are no service conductors and there is no service.

Why are two sets 400A too small?

Between the XFMR and the disconnect in building 280.

 

[don_resqcapt19]

Why are two sets 400A too small?

There is only one set of 500 kcmil rated at 380 amps between the transformer secondary and the line side of the 400 amp OCPD. They are too small because the "round-up" rule in 240.4(B) does not apply. The are too small because the text in 240.21(C) says: "Section 240.4(B) shall not be permitted for transformer secondary conductors." That language requires 600 kcmil copper between the transformer and line side of the OCPD.

 

[EngineeredElectric]

Step up transformer has 300KVA written on it but the note says it's 225KVA. Which one is it? Sloppy.
I hope those existing 4" underground conduits aren't full of mud. If this was around here it is safe to assume that they are.
That 480v feeder circuit might be better off if it was 600v. Not sure what the distances are, but I assume they want 2 sets of 400mcm for voltage drop reasons. 600v will handle the voltage drop better and require less base ampacity.
Likewise using aluminum instead of copper for the 480v feeders would probably saves tens of thousands of dollars in material depending on the distance, but many smart people are very anti AL conductors for various reasons. Maybe they already are aluminum and that's why they are so big.

Everyone else already covered the important points. Most notably that, no, the xfrmr and switch is building 101 in NOT considered another service. If the architect is referring to the switch on building 101 as a "Main service switch" then yeah... even more sloppy.

Good job involving more brains in the planning process. It will pay dividends.