OT: 2-pole Circuit Breaker in Single Phase Supply

bkottaras · Jan 28, 2019

Just buy what they recommend.
Cables (twists/meter), plugs, the analogue volt meter used to set to desired temperature and read it for the "push" to calibrate setup.
We do use an enclosure to mount the hardware near your heater assembly, makes life easier if you can manage that.

Jonnie_R · Jan 29, 2019

kamenges said:
Follow-up question. I assume the neutral conductor will no longer be blue after the circuit breaker since you can no longer say that wire is definitely a grounded conductor. Correct assumption?

Keith

They recommend light blue for the neutral if it has no other identifying marks. To be fair though people tend to stick to what they've used for years.

I have a copy of the guidance regs from 2006 if you'd like a copy to help. It should still be fairly current, as there was an addendum in 2009 and a new version only last year.

kamenges · Jan 29, 2019

Jonnie_R, if you could just pass on the document number of the guidance regs that would be much appreciated. That is something we should have around here anyway.

It surprises me some that they recommend sticking with blue on the load side of the breaker. But if that's what they want, who am I to say differently from 4000 miles away?

Keith

rscott9399 · Jan 29, 2019

We always switch the neutral in single phase applications.

I am assuming you are going line to line for your 230 VAC

But yes this may include a color change because technically the neutral is not really neutral its another line.

Jonnie_R · Jan 30, 2019

kamenges said:
Jonnie_R, if you could just pass on the document number of the guidance regs that would be much appreciated. That is something we should have around here anyway.

It surprises me some that they recommend sticking with blue on the load side of the breaker. But if that's what they want, who am I to say differently from 4000 miles away?

Keith

Keith,

I've sent you a message.

Jon

tragically1969 · Jan 30, 2019

kamenges said:
Jonnie_R, if you could just pass on the document number of the guidance regs that would be much appreciated. That is something we should have around here anyway.

It surprises me some that they recommend sticking with blue on the load side of the breaker. But if that's what they want, who am I to say differently from 4000 miles away?

Keith

I have never seen the neutral conductor change colour through a breaker or protective device.

Aabeck · Jan 30, 2019

tragically1969 said:
I have never seen the neutral conductor change colour through a breaker or protective device.

It should have the color changed, if the device opens it is no longer neutral.

tragically1969 · Jan 30, 2019

Aabeck said:
It should have the color changed, if the device opens it is no longer neutral.

And if it's closed what is it then?

kamenges · Jan 30, 2019

Originally posted by tragically1969:

And if it's closed what is it then?

Soooo....I should tell them to never open the breaker?

Aabeck's point about the common conductor switched by a motor overload seems the closest to this situation. I'm not sure what is done with this conductor in EU countries but in the US this conductor is not the neutral color since you can't unconditionally say this conductor will be at ground potential.

The whole use of color to identify a grounded neutral conductor for safety reasons is a flawed concept to begin with, but I digress. As I said above, who am I to tell people what to do from 4000 miles ( 6400 km) away? I do silly things every day just because code says we have to. I'm really interested in just doing what is done in the region so the system fits in.

Keith

tragically1969 · Jan 30, 2019

kamenges said:
Soooo....I should tell them to never open the breaker?

Aabeck's point about the common conductor switched by a motor overload seems the closest to this situation. I'm not sure what is done with this conductor in EU countries but in the US this conductor is not the neutral color since you can't unconditionally say this conductor will be at ground potential.

The whole use of color to identify a grounded neutral conductor for safety reasons is a flawed concept to begin with, but I digress. As I said above, who am I to tell people what to do from 4000 miles ( 6400 km) away? I do silly things every day just because code says we have to. I'm really interested in just doing what is done in the region so the system fits in.

Keith

My point is when it's closed it's a Neutral when its Open its still a Neutral.

I'm not really following the thread that closely to be honest or quite understand your exact arrangement but in the UK the Neutral conductor doesn't change colour through a Fuse or MCB

Aabeck · Jan 30, 2019

tragically1969 said:
My point is when it's closed it's a Neutral when its Open its still a Neutral.

When it is open it is no longer a neutral. In the example of a motor over-load controlling the neutral to a contactor, when the over-load relay opens the wire to the neutral side of the coil has the potential of the coil power if the control still energizes it (PLC not looking at overload signal, simple on/off switch, etc.)

In that circumstance if the wire to the contactor was still neutral color, and someone expected it to have a 0 volt to ground potential they could get zapped if it was a 120VAC or 220VAC coil.



                        Charged 'Neutral'          Open OLR               

120VAC>---||-------()-----------------------------|/| |OPEN| |/|----<N

Jonnie_R · Jan 30, 2019

With a 2P MCB the poles are not independent of each other. If one pole trips they both trip, therefore there would be no voltage at the device. Double pole isolation is a fairly standard thing in Europe.

JesperMP · Jan 30, 2019

As long as we are talking about a control voltage inside a control cabinet, then the neutral is not interrupted by the circuit breaker for the live phase.
It is common to have several single phase potentials for various functions, each with its own circuit breaker. But the neutral is common for all single phases and not interrupted. Because of that it is always tied to the supply voltage neutral. If there is a step-down transformer for the control voltage (there almost always is), then the neutral is tied to the ground at the output of the transformer.
Because of the above, in the scenario that Aabeck pointed out, the voltage in the neutral coming the "wrong way" will be neutralized.

If there is a single phase supply going out of the control cabinet (very rare nowadays), then both phase and neutral are interrupted by the circuit breaker.

This is how we do it, and I am pretty sure it is the correct way. But I cannot on the spot point to where in EN60204-1 it says so.

tragically1969 · Jan 30, 2019

Aabeck said:
When it is open it is no longer a neutral. In the example of a motor over-load controlling the neutral to a contactor, when the over-load relay opens the wire to the neutral side of the coil has the potential of the coil power if the control still energizes it (PLC not looking at overload signal, simple on/off switch, etc.)

In that circumstance if the wire to the contactor was still neutral color, and someone expected it to have a 0 volt to ground potential they could get zapped if it was a 120VAC or 220VAC coil.

Charged 'Neutral' Open OLR
120VAC>---||-------()-----------------------------|/| |OPEN| |/|----<N

Not quite sure your example is relevent.

We are talking about a 230VAC Live and Neutral supply to a controller, protected by a DP MCB and specifically in the EU zone are we not ?

In the UK lets assume that would be off L1 and N, so Brown and Blue (using the harmonized standards for phase colouring) you wouldn't change the colour of the neutral conductor thorugh the device, neither would you in mainland EU to my knowledge.

kallileo · Jan 30, 2019

tragically1969 said:
Not quite sure your example is relevent.

We are talking about a 230VAC Live and Neutral supply to a controller, protected by a DP MCB and specifically in the EU zone are we not ?

In the UK lets assume that would be off L1 and N, so Brown and Blue (using the harmonized standards for phase colouring) you wouldn't change the colour of the neutral conductor thorugh the device, neither would you in mainland EU to my knowledge.

We don't do it as well and never seen anyone else changing colors.
Normally we are using single pole MCB's with exception on machines that are plugged directly into socket where the phase and the neutral can be swapped.

OT: 2-pole Circuit Breaker in Single Phase Supply

bkottaras

Member

Jonnie_R

Member

kamenges

Member

rscott9399

Member

Jonnie_R

Member

tragically1969

Member

Aabeck

Member

tragically1969

Member

kamenges

Member

tragically1969

Member

Aabeck

Member

Jonnie_R

Member

JesperMP

Lifetime Supporting Member + Moderator

tragically1969

Member

kallileo

Lifetime Supporting Member

Similar Topics