OK to run the Neutral wire thru a Disconnect?

skyfox

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Is it OK to run the Neutral wire thru a disconnect switch for a electrical control panel as shown below? If not, can someone elaborate as to why it shouldn't be done?


Thanks

Disconnect.png
 
I have some 'jogging tables' where the hot and neutral are
opened by the On / Off switch so I am curious about this.

Poet.
 
The neutral wire can be broken by a circuit breaker or switch (including disconnect) ONLY if it is broken with the hot lead.



It is not allowed to break the neutral and potentially have the hot lead live. So your drawing is allowed.
 
The neutral must always be disconnect through a multi pole circuit breaker that also cuts the all live phase(s) at the same time.

This is even more important for three-phase systems since a fortuitous disconnection of the neutral can have serious consequences.
 
Tel me about it, one of our engineers removed a neutral link as well as disconnect the 3 phases with the isolator but forgot to put the link in before switching on, PLC & 4 inverters + PSU lit up like a Christmas tree as these were all single phase devices split between phases. Tip never install removable neutral links and if required, use 4 pole isolators if neutral needs to be disconnected. The neutral should be at the same potential as the earth (usually tied at source), however this cannot be guaranteed due to resistance of cables so disconnecting neutral with the phases is not a bad idea.
 
I have said it many times and will repeat: a neutral is something that MAY be grounded while GND/PE is something that always IS.

Although neutrals are grounded probably 99.5% of the time, assuming it to be 100% is not safe. Therefore - yes, break the neutral and the phase/hot lines together.
 
I don't know about in the UK, but here it's the earth ground that has to be made first and disconnected last. The neutral can be switched simultaneously with the hot lead(s).
 
You've got two different questions here; cord-connected equipment and a single-phase disconnect switch.

While you're only required to break the non-grounded conductors with a disconnect, there is a nonzero chance that you will connect to a source with a floating neutral, or that somebody will substitute a non-polarized plug or adapter.

When I have a single-phase disconnect like the one shown, I always break both the L1 and the N conductors.

The Ground either always stays connected (as shown) or is part of a "make first, break last" mechanism. That's why the ground pin on a power cord is longer than the power blades.
 
I may be wrong, but isn't there a requirement for 4 pole breakers to open the Neutral last or to connect Neutral first with a couple of ms interval?

You are & no there isn't.

In the UK / EU, the Neutral is classed as a live conductor, it should be treated exactly the same as P1, 2 or 3
 
From another angle, why do you need a disconnect anyway when the thing can be unplugged. You don't have a disconnect on your washer or dryer, if you want to work on it you just unplug. But to argue with myself I always use switched sockets, so what do I know.
 
Why disconnect it at all? Seems like there are fewer rules to worry about if you do not disconnect it, at least in most USA areas.
 
Why disconnect it at all? Seems like there are fewer rules to worry about if you do not disconnect it, at least in most USA areas.

Because there is no 100% guarantee that the neutral of the customer's supply does not have some voltage with respect to ground.

And because there should be some way to completely isolate the equipment from the supply.
 

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