1000 volts

[mbrooke]

I see under the 2014 600 volts is being boosted to 1000 volts in some places (wording wise).


My question is this. If one had has say a motor rated above 600 volts but under 1000 volts or has a 480/830 volt grY distribution system, can one treat this installation as an LV? Have LV standards apply rather than MV?



The way Im reading the prior code is once one goes over 600 volts like in a 480/830 volt system you have to use MV rated cables along with MV switchgear?

Thanks!

 

[don_resqcapt19]

I see under the 2014 600 volts is being boosted to 1000 volts in some places (wording wise).


My question is this. If one had has say a motor rated above 600 volts but under 1000 volts or has a 480/830 volt grY distribution system, can one treat this installation as an LV? Have LV standards apply rather than MV?



The way Im reading the prior code is once one goes over 600 volts like in a 480/830 volt system you have to use MV rated cables along with MV switchgear?

Thanks!

As far as the rating of the equipment and the conductors there is no change. In both the 2011 and 2014 codes, those items have to be rated for the voltage. There are some other changes because the installation is no longer covered by the "high" voltage rules, but not a lot.

 

[Jraef]

I see under the 2014 600 volts is being boosted to 1000 volts in some places (wording wise).


My question is this. If one had has say a motor rated above 600 volts but under 1000 volts or has a 480/830 volt grY distribution system, can one treat this installation as an LV? Have LV standards apply rather than MV?



The way Im reading the prior code is once one goes over 600 volts like in a 480/830 volt system you have to use MV rated cables along with MV switchgear?

Thanks!

Not sure where you are seeing this reference to 1000V, but I don't have a 2014 yet. I can only imagine though that you might be seeing it in reference to solar PV systems, because a lot of them are moving to 1000VDC on the PV side to keep costs down on transmission conductors back to combiner boxes etc. But regardless, UL still classifies anything over 600VAC RMS as Medium Voltage regardless of the wording in the NEC, so unless that changes, it's a moot point. You will have to use MV gear on anything over 600V.

It might be about to change however. I recently read an article about how UL is beginning a process of "harmonizing" it's standards to equivalent IEC standards. One of the IEC standards is that LV is defined as 1000V and under, because they have a lot of 690V systems in use for certain industries and in underground mining trailing equipment, 1000VAC is used quite a bit. So if it is true that UL will harmonize, then we might be there in a few years. It will likely take equipment mfrs and wire insulation systems a while to change though even after that.

 

[don_resqcapt19]

Not sure where you are seeing this reference to 1000V, but I don't have a 2014 yet. I can only imagine though that you might be seeing it in reference to solar PV systems, because a lot of them are moving to 1000VDC on the PV side to keep costs down on transmission conductors back to combiner boxes etc. But regardless, UL still classifies anything over 600VAC RMS as Medium Voltage regardless of the wording in the NEC, so unless that changes, it's a moot point. You will have to use MV gear on anything over 600V.

It might be about to change however. I recently read an article about how UL is beginning a process of "harmonizing" it's standards to equivalent IEC standards. One of the IEC standards is that LV is defined as 1000V and under, because they have a lot of 690V systems in use for certain industries and in underground mining trailing equipment, 1000VAC is used quite a bit. So if it is true that UL will harmonize, then we might be there in a few years. It will likely take equipment mfrs and wire insulation systems a while to change though even after that.

Jeff, in the 2014 the reference to "over 600 volts" was changed to "over 1,000 volts" though out the code, except for the code articles that are under the control of Code Making Panels, 1 and 8.

 

[Jraef]

Jeff, in the 2014 the reference to "over 600 volts" was changed to "over 1,000 volts" though out the code, except for the code articles that are under the control of Code Making Panels, 1 and 8.

Ah, sounds like maybe the process has begun then. I've been noticing a number of wire suppliers offering 1000V rated insulation on XLPE insulation (RHHW) as well, but I thought maybe that was just for VFD cable. Maybe not, maybe it's because the future is already upon us.

 

[mbrooke]

Not sure where you are seeing this reference to 1000V, but I don't have a 2014 yet. I can only imagine though that you might be seeing it in reference to solar PV systems, because a lot of them are moving to 1000VDC on the PV side to keep costs down on transmission conductors back to combiner boxes etc. But regardless, UL still classifies anything over 600VAC RMS as Medium Voltage regardless of the wording in the NEC, so unless that changes, it's a moot point. You will have to use MV gear on anything over 600V.

It might be about to change however. I recently read an article about how UL is beginning a process of "harmonizing" it's standards to equivalent IEC standards. One of the IEC standards is that LV is defined as 1000V and under, because they have a lot of 690V systems in use for certain industries and in underground mining trailing equipment, 1000VAC is used quite a bit. So if it is true that UL will harmonize, then we might be there in a few years. It will likely take equipment mfrs and wire insulation systems a while to change though even after that.

Is there any way out of useing MV gear in something over 600 volts but under 1000? The IEC makes an exception like you said, but any North American gear?

 

[kingpb]

I would suspect, that with the rest of the world following IEC, that ANSI/IEEE is starting to align themselves in many instances with IEC where possible. In IEC, LV is 1000V and below. Cable is already available, albeit in sizes designated as mm², not KCMIL or AWG.

 

[Jraef]

I was just involved in a discussion about UL listing of some of our equipment and changes that sales people want to see. In the explanation from management as to why it is not going to happen, they said point blank "Because UL508C will become invalid in 2018 anyway and replaced by a new standard that is aligned with IEC requirements. So until we see exactly what those will be we are not going to pursue changes to our UL508C listings." I bring it up because that's the first I have heard that there is an actual date set.

 

[kwired]

Probably is mostly (the beginning stages of) an alignment with the rest of the world and seeing 1000 volts as the division between low and medium voltages.

Conductors are kind of a base, next we may very well see more equipment rated 1000 volts. Things like switchboards and panelboards are either 600 volts (or less) or next step up is likely at least 2500 or even 5000 I would guess - I don't work with those voltages so I really don't know.