What does S/N stand for in these pictures?

[leeradney]

These pictures are from a Refrigeration and AC textbook. Can you tell me what the S/N stands for?

 

[ggunn]

These pictures are from a Refrigeration and AC textbook. Can you tell me what the S/N stands for?

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S/N usually means serial number.

 

[zbang]

In context it looks like it could be "service neutral". Serial number doesn't make sense there.

 

[ggunn]

In context it looks like it could be "service neutral". Serial number doesn't make sense there.

Agreed; I hadn't looked at the drawings. Is there an abbreviations page in the first few pages of the drawing set? It's not fair to use an abbreviation and not explicitly define it somewhere.

 

[david luchini]

S/N means "solid neutral" in your pictures.

Here's a panelboard example...

http://static.schneider-electric.us...r Distribution Panelboard/80043-268-06_en.pdf

 

[texie]

These pictures are from a Refrigeration and AC textbook. Can you tell me what the S/N stands for?

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S/N stands for Solid Neutral. This is a standard way of delineating a neutral connection that is not switched, as is the case for most panels except in very rare cases where the neutral is switched.

 

[Harley_Squires]

Takeing things off subject

Takeing things off subject

In what sort of application would the neutral be switched? Just curious.

 

[GoldDigger]

In what sort of application would the neutral be switched? Just curious.

Technically, a neutral does not have to be a grounded conductor, although with very few exceptions the NEC requires the neutral of a system that has one to be grounded.

So if the neutral is not grounded, it must be switched both by disconnect switches and by OCPDs that are required to open all ungrounded conductors.

The most common case in which a neutral is switched, however, is when an automatic or manual transfer switch replaces the service as a power source with a supply that is considered an SDS. Since the SDS will have its own ground-neutral bond, the TS must disconnect the load neutral from the ground-neutral bond which is located on the service side.

 

[Dennis Alwon]

In what sort of application would the neutral be switched? Just curious.

When you have a generator and you want a separately derived system then the neutral is switched in the transfer switch. Not sure when else it would happen for a service

 

[Harley_Squires]

Thanks.