# Practicality of 400 volt equipment

Discuss Practicality of 400 volt equipment in the Electrical Forum area at ElectriciansForums.net

C

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but if you are going to start using phase to phase voltages, then you must start distributing 3 phase supplies - that's a two fold increase in the amount of copper used, plus all switchgear would be three phase etc.

That is a significant increase in costs - a 1.73 reduction in cable size balancing a 2 fold increase in the number of cables

No necessarily- you could drop two phases and an earth at each property.

100 x 230 =23,000va / 400 volts= 57.5 amps or 63 amp main fuse.

3 phase would give 33 amps per phase or a 35 amp main fuse.

In both cases the main would use thinner copper, and in the 3 phase example the number of wires do not change in that a 4th neutral is provided as is.

J

#### Julie.

Esteemed
Arms
No necessarily- you could drop two phases and an earth at each property.

100 x 230 =23,000va / 400 volts= 57.5 amps or 63 amp main fuse.

3 phase would give 33 amps per phase or a 35 amp main fuse.

In both cases the main would use thinner copper, and in the 3 phase example the number of wires do not change in that a 4th neutral is provided as is.
In which case you cannot use 230V equipment!

it's only 400V in relation to a three phase circuit - each breaker is only operating at 230V if you use a single breaker then it must be 400V

All UK domestic equipment is 230v, switches etc

Yes SOME industrial kit is rated at 660V - but even that isn't sufficient, you would need 800v three phase kit for each breaker to open single phase 400V (700V but that's not standard)

A three phase set of breakers does not mean each is capable of opening 400V

#### Pete999

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Esteemed
Arms
Why - many large industrial sites use 3.3kV motors and so on.

The voltage isn't fixed at 230 (or 110) - that's just the most suitable for most end users taking into account the factors.

Like why we use 3 phase and not 7 phase and so on - it achieves the best balance given the technology we have
Sorry Julie disagree with your reasoning

J

Esteemed
Arms

Esteemed
Arms

Esteemed
Arms

J

#### Julie.

Esteemed
Arms
Your reasoning shows no essence just random wording.
Well I thought it made sense!

It is still possible to use any voltage you want to suit your purpose, yes there are standards such as 230/400, or 380/660, or 1000v as per iec 60038.

However the 230/400 is most common purely because for the most part the current levels are manageable i.e cable sizes, the insulation needs are not onourous and most simple circuit breaker technologies can handle it.

That's why it has become the standard from all the options.

In the same way three phase makes the most sense - its more efficient than single or two phase, but also no less efficient than 4, 5,6,7.... phase.

Does that make it clearer?
Post automatically merged:

There are lots of equipment that is single phase 400v - but its usually just in industrial settings, for example control transformers are usually phase to phase as there often isn't a neutral.

I took the op to mean why don't we use 400v across the board as standard rather than 230v

C

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In which case you cannot use 230V equipment!

it's only 400V in relation to a three phase circuit - each breaker is only operating at 230V if you use a single breaker then it must be 400V

All UK domestic equipment is 230v, switches etc

Yes SOME industrial kit is rated at 660V - but even that isn't sufficient, you would need 800v three phase kit for each breaker to open single phase 400V (700V but that's not standard)

A three phase set of breakers does not mean each is capable of opening 400V
Right.

400 volt rated switches, sockets and light fittings.

Two and 3 pole breakers are already slash rated 230/400Y.

C

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Are the coils 400 volts or just multiple 230 volt coils?

#### westward10

Mod
Your reasoning shows no essence just random wording.
I have absolutely no idea why you disagree with @Julie. and your response is quite frankly ridiculous.

J

#### Julie.

Esteemed
Arms
Right.

400 volt rated switches, sockets and light fittings.

Two and 3 pole breakers are already slash rated 230/400Y.
In terms of iec equipment 230/400 refers to 230v ph - e/n and 400v ph-ph

They are only suitable for 400v if they are multiple pole.

C

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Well I thought it made sense!

It is still possible to use any voltage you want to suit your purpose, yes there are standards such as 230/400, or 380/660, or 1000v as per iec 60038.

However the 230/400 is most common purely because for the most part the current levels are manageable i.e cable sizes, the insulation needs are not onourous and most simple circuit breaker technologies can handle it.

That's why it has become the standard from all the options.

In the same way three phase makes the most sense - its more efficient than single or two phase, but also no less efficient than 4, 5,6,7.... phase.

Does that make it clearer?
Post automatically merged:

There are lots of equipment that is single phase 400v - but its usually just in industrial settings, for example control transformers are usually phase to phase as there often isn't a neutral.

I took the op to mean why don't we use 400v across the board as standard rather than 230v

6 phase is actually more efficent, but I've read that its not worth the extra complexity.

If we were to mass produce 400 volt consumer products, would it be more expensive than 230 volt consumer was my primary questions- though its not really confined to that only. Anything and everything is open to discussion around this subject.

In terms of iec equipment 230/400 refers to 230v ph - e/n and 400v ph-ph

They are only suitable for 400v if they are multiple pole.
True. The only thing that will need to be re-designed are single pole switches.

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