what type of switchboard is this?

[Grouch1980]

Hi all,
I'm in the midst of designing a hotel in NYC... I came across the hotel's design standards, which mention this for the main switchboard:

"Main Switchboard: Provide breakers with main disconnect switches with GFI and transient voltage surge suppression (TVSS) protection"

How do you interpret this?...
a) Does the service switch have to be a circuit breaker or a fused disconnect switch?
b) Do the secondary switches (tapping off the service switch, and still part of the main switchboard) have to be circuit breakers or fused disconnects?

Thanks!!

 

[infinity]

I read it several times and like you I have no idea what they're looking for. :roll:

 

[Smart $]

What are the system voltage and ampere rating?

The only one that can really answer this is the party which issued the specifications. All we can do is speculate.

Is "Main" synonymous with "Service"?

Is "Switchboard" synonymous with "Panelboard"?

Is "GFI" synonymous with "GFP"?

 

[Grouch1980]

I was able to take upload a snapshot of the text i'm looking at. Look at 3a. I'm thinking they mean to just use fused disconnect switches at the main switchboard. If you look at 3c, they actually say 'circuit breaker type' for the panelboards... they only said 'breakers' for the main switchboard, which leads me to believe they just want some kind of OCPD at the main switchboard that 'breaks' the current... so fused disconnect switches I believe would suffice (if not they would've said 'circuit breaker type' for the main switchboard). Any thoughts?

The voltage for the building is 120/208 volts, so we wouldn't need GFP devices at the switches. The amperage is 3,000 amps.

 

[infinity]

What is a "main switchboard" in this context is this a service?

 

[Grouch1980]

I'm assuming they mean 'service switchboard'. it is vague.

 

[gadfly56]

I'm assuming they mean 'service switchboard'. it is vague.

Sounds like an RFI to the engineering firm is in order.

 

[charlie b]

I think the person who wrote this is not familiar enough with the language of our profession. Any of us would normally not associate a breaker and the word "switch." But if you start by accepting that the author doesn't understand the terminology, and you look beyond the words as written, you might be able to see a more reasonable intention behind the words. I believe the phrase "main disconnect switches" is intended to mean that the portion of the circuit breaker that performs the disconnecting function needs to include the Ground Fault and the TVSS capabilities. In other words, "switch" refers to a portion of the breaker.

 

[gadfly56]

I think the person who wrote this is not familiar enough with the language of our profession. Any of us would normally not associate a breaker and the word "switch." But if you start by accepting that the author doesn't understand the terminology, and you look beyond the words as written, you might be able to see a more reasonable intention behind the words. I believe the phrase "main disconnect switches" is intended to mean that the portion of the circuit breaker that performs the disconnecting function needs to include the Ground Fault and the TVSS capabilities. In other words, "switch" refers to a portion of the breaker.

At the risk of repeating myself, an RFI is in order. You don't want to order 3,000 amp switch gear without the clearest understanding of what's required.

 

[Smart $]

What are the system voltage and ampere rating?

The only one that can really answer this is the party which issued the specifications. All we can do is speculate.

Is "Main" synonymous with "Service"?

Is "Switchboard" synonymous with "Panelboard"?

Is "GFI" synonymous with "GFP"?

Sounds like an RFI to the engineering firm is in order.

At the risk of repeating myself, an RFI is in order. You don't want to order 3,000 amp switch gear without the clearest understanding of what's required.

I agree No. 2.

 

[Smart $]

...
The voltage for the building is 120/208 volts, so we wouldn't need GFP devices at the switches. The amperage is 3,000 amps.

If the "main" is a service, please refer to 230.95 Ground-Fault Protection of Equipment.

Essentially under 1000 volts, over 1000A-rated service disconnecting means, requires GFP. This is why many designs break the service into several disconnecting means rated under 1000A.

GFI is not an equivalent for GFP

 

[infinity]

If the "main" is a service, please refer to 230.95 Ground-Fault Protection of Equipment.

Essentially under 1000 volts, over 1000A-rated service disconnecting means, requires GFP. This is why many designs break the service into several disconnecting means rated under 1000A.

GFI is not an equivalent for GFP

Wouldn't 208Y/120 would be less than 150 volts to ground?

230.95 Ground-Fault Protection of Equipment. Groundfault protection of equipment shall be provided for solidly
grounded wye electric services of more than 150 volts to ground but not exceeding 600 volts phase-to-phase for each
service disconnect rated 1000 amperes or more. The grounded conductor for the solidly grounded wye system
shall be connected directly to ground through a grounding electrode system, as specified in 250.50, without inserting
any resistor or impedance device.

 

[Smart $]

Wouldn't 208Y/120 would be less than 150 volts to ground?

Ahhh, yes. My bad. Yesterday was just not my day. :ashamed1:

 

[ron]

I would suggest that if you are getting a 120/208V service from Con Ed at 3000A, depending on the neighborhood, you will be getting it off of the low voltage network grid of transformers, which means that your AIC will need to be 200kA.

Bolted pressure switches with fuses will be the most economical way of reaching 200kA. You can also locate them in a SWBD configuration.

 

[Grouch1980]

I would suggest that if you are getting a 120/208V service from Con Ed at 3000A, depending on the neighborhood, you will be getting it off of the low voltage network grid of transformers, which means that your AIC will need to be 200kA.

Bolted pressure switches with fuses will be the most economical way of reaching 200kA. You can also locate them in a SWBD configuration.

Thank you all for the responses. It was mentioned here sending an RFI on this, which is the route I may take. I showed the text to my supervisor, his response was that it was written by someone who has no clue what they're talking about :happyno::happyno:

I agree Ron, using fuses are the way to go if the available short circuit current is that high. Honestly, I think I only once remember seeing a circuit breaker as the main service switch for a building... you typically always see fuses.

 

[AZJeff2013]

Hotel Service Entrances

Hotel Service Entrances

Hi all,
I'm in the midst of designing a hotel in NYC... I came across the hotel's design standards, which mention this for the main switchboard:

"Main Switchboard: Provide breakers with main disconnect switches with GFI and transient voltage surge suppression (TVSS) protection"

How do you interpret this?...
a) Does the service switch have to be a circuit breaker or a fused disconnect switch?
b) Do the secondary switches (tapping off the service switch, and still part of the main switchboard) have to be circuit breakers or fused disconnects?

Thanks!!

90% of the design work I do is hotel work. That looks like the spec from either the Marriott or IHG design guidelines. You will be fine with a main circuit breaker (with GFP) and distribution circuit breakers for your panelboards and any other feeds to equipment. I have yet to design a service for a hotel with fused switches.

 

[Grouch1980]

90% of the design work I do is hotel work. That looks like the spec from either the Marriott or IHG design guidelines. You will be fine with a main circuit breaker (with GFP) and distribution circuit breakers for your panelboards and any other feeds to equipment. I have yet to design a service for a hotel with fused switches.

Sorry for the late reply!.... my supervisor still prefers to use a service switchboard with fused switches. i'm actually curious... if i ever walk into a hotel, i'll be on the lookout to see what they installed at the service switchboard.

 

[Fulthrotl]

I would suggest that if you are getting a 120/208V service from Con Ed at 3000A, depending on the neighborhood, you will be getting it off of the low voltage network grid of transformers, which means that your AIC will need to be 200kA.

Bolted pressure switches with fuses will be the most economical way of reaching 200kA. You can also locate them in a SWBD configuration.

i've no experience with NYC, is the grid there that robust that 200k is commonly needed on a service there?

 

[iwire]

Sorry for the late reply!.... my supervisor still prefers to use a service switchboard with fused switches. i'm actually curious... if i ever walk into a hotel, i'll be on the lookout to see what they installed at the service switchboard.

The company I work for installs many services from 800 amps to 4000 amps and the vast majority are all breaker switchgears. Very rare for us to used fused switchboards.

Once in a while bolted pressure switch mains with GFP feeding breaker switchgear sections.

 

[kwired]

Sorry for the late reply!.... my supervisor still prefers to use a service switchboard with fused switches. i'm actually curious... if i ever walk into a hotel, i'll be on the lookout to see what they installed at the service switchboard.

How often would that be something you could look at without permission to go into an area where guests typically aren't allowed?