RV Pedestal Bonding

[david]

Are you considering a Utility Transformer a "Secondary" distribution Transformer?
JAP>

I may have missed it but I didn't find an NEC definition of a secondary distribution system

From a Google search a 3ph system in RV parks are not that uncommon.

It seems it would look similar to what is discussed in this thread.

The NEC makes the statement that a grounding electrode is not required unless it is service equipment.

Also the equipment ground would originate with the supply conductors in the transformer

The transformer must be grounded

From our prospective it sounds like a feeder. But identified as a secondary distribution system

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[jap]

I may have missed it but I didn't find an NEC definition of a secondary distribution system

From a Google search a 3ph system in RV parks are not that uncommon.

It seems it would look similar to what is discussed in this thread.

The NEC makes the statement that a grounding electrode is not required unless it is service equipment.

Also the equipment ground would originate with the supply conductors in the transformer

The transformer must be grounded

From our prospective it sounds like a feeder. But identified as a secondary distribution system

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It's not a feeder if the pedestals are fed directly from the Utility Transformers since there is no OCPD device between the Utility Transformer and the Pedestal.

Jap>

 

[david]

It's not a feeder if the pedestals are fed directly from the Utility Transformers since there is no OCPD device between the Utility Transformer and the Pedestal.

Jap>

Article 551 amends other articles in the NEC
It allows for a secondary Distribution System
It amends article 250 in stating a grounding electrode is not required at the RV site when a equipment ground originates in the transformer and is run with the secondary distribution conductors
As already pointed out in this thread there was a time when six disconnect rule would have been applied at the RV site

Here only at residential sites does the utility company supply the secondary conductors from utility transformers

In Penn Powers area the electrician supplies the secondary conductors then Penn power connects them
In Duquesne Light's area the electrician supplies the secondary conductors and also make the connections
West Penn Power does the same as PennPpower
Municiple utilities all have their own rules

How would you define a secondary distribution system and what would it looklike at a mobile home park, RV park or perhaps a collage campus?

You would not normally see an equipment ground run with the secondary transformer conductors but if you did what would you call the conductors. We k now unless there is over current protection ahead of the conductors you would not call it a feeder.

so what does the term secondary distribution system mean?

 

[kwired]

Article 551 amends other articles in the NEC
It allows for a secondary Distribution System
It amends article 250 in stating a grounding electrode is not required at the RV site when a equipment ground originates in the transformer and is run with the secondary distribution conductors
As already pointed out in this thread there was a time when six disconnect rule would have been applied at the RV site

Here only at residential sites does the utility company supply the secondary conductors from utility transformers

In Penn Powers area the electrician supplies the secondary conductors then Penn power connects them
In Duquesne Light's area the electrician supplies the secondary conductors and also make the connections
West Penn Power does the same as PennPpower
Municiple utilities all have their own rules

How would you define a secondary distribution system and what would it looklike at a mobile home park, RV park or perhaps a collage campus?

You would not normally see an equipment ground run with the secondary transformer conductors but if you did what would you call the conductors. We k now unless there is over current protection ahead of the conductors you would not call it a feeder.

so what does the term secondary distribution system mean?

I didn't double check but if this so called secondary distribution system I could see allowed for separately derived systems but not from a utility transformer. A service conductor is still a service conductor up to the service disconnecting means regardless if customer or utility supplied/owned. The difference in more recent editions of NEC is utility service conductors are called service drop or lateral where customer service conductors are simply called overhead or underground service conductors. The "service point is where these names change even if said service point is an unbroken point in a conductor.

 

[david]

I didn't double check but if this so called secondary distribution system I could see allowed for separately derived systems but not from a utility transformer.

Perhaps but the only definitions of a secondary Distrubution Systems that I found so far indicate the system is part of the utility network involving network transformers. A description all underground and a lot of times 3 ph

Being defined as the final leg of the utility network

Article 551 indicates that the equipment ground would originate in the transformer and the neutral could not be used as an equipment ground

No grounding electrode required at the RV site

If the NEC means some other type of secondary distribution system than it should be defined in the NEC. it's possible that I missed or have not found the definition


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[kwired]

If you are referring to what is mentioned in 551.76(C)

it about has to be talking about secondary of a customer owned "separately derived system" transformer.

Secondary of utility transformer is considered service conductors up to the service disconnecting means.

With separately derived systems you generally have a choice of grounding at the transformer or at the first disconnecting means. I think all they are saying here is you must ground that system at the transformer. If you have a single overcurrent device after the transformer this section doesn't apply you still can ground at transformer or the first disconnect. After that first disconnect you have ordinary feeders again.