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Domestic Installation

04/30/2010 6:29 PM

What does the acronym TPN stand for? In domestic installation which comes first the TPN or the Distribution board?

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#1

Re: Domestic Installation

04/30/2010 9:10 PM

Should be standing for: Triple Pole (or Phase) Neuter (or Neutral) linked Switch.

The main 3 phase switch, mainly for Star (Y) supply.

Where to put it depends on what you have in your Distribution board.

If you want to fuse it too It will be placed between your main disconnect breaker or fuses and your distribution panel.

In high voltage, these fuses are mostly part of the supplier.

A TPN there is your first component, when you don't count the fuses from the supplier.

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#2
In reply to #1

Re: Domestic Installation

04/30/2010 9:54 PM

Type of breakers based on number of pole:

Based on the number of poles, the breakers are classified as

SP – Single Pole

SPN – Single Pole and Neutral

DP – Double pole

TP – Triple Pole

TPN – Triple Pole and Neutral

4P – Four Pole

The difference between TPN and 4P (or SPN and DP):

For TPN, protection applies to the current flow through only 3 poles; there is no protection for the current flow through the neutral pole. For the 4 pole breakers, protection applies to current flow through all poles. However when breaker trips or manually opened, all poles are disconnected.

Same type of difference also applies for SPN and DP.

Usage of TP, TPN and 4P in distribution panel:

For any distribution board, the protection system (either fuse and switch or breaker) must be used in the incomer. For a three phase distribution panel, either TP or TPN or 4P can be used as the incoming protection.

TP: It is most commonly used type in all ordinary cases.

TPN: It is generally used where there are dual sources of incomer to the panel (utility source and emergency generator source).

4P: It is used where is the possibility of high neutral current (due to unbalance loads and /or 3rd and multiple of 3rd harmonics current etc).

- MS

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#3
In reply to #2

Re: Domestic Installation

04/30/2010 10:44 PM

Your explanation is very extended and useful. I used the word switch intentionally, because however they can both disconnect, the function of a breaker is not a switch and a switch is not a (fused) breaker.

Many countries require, besides a main breaker, also a main switch.

TP for delta, TPN for Y (or star) The connection between ground and neutral is in many countries not allowed. Therefore the N is also switched.

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Re: Domestic Installation

02/19/2022 8:25 PM
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