Low Voltage EGC requirements
- Thread starter Stonewall
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Buck Parrish
Senior Member
- Location
- NC & IN
I'm pretty sure that it is 24 volts.
- Location
- Illinois
- Occupation
- retired electrician
This depends on what the 24 volts is used for. There is no lower limit on the rules in Article 250, but there are rules in some Chapter 7 Articles that say you don't need the EGC.
- Location
- Illinois
- Occupation
- retired electrician
Stonewall said:
If there is no mention, then the rules in Article 250 apply since the rules in Chapters 5-7 supplement or modify the rules in Chapters 1-4.
I have never seen an EGC on a 24Vdc control circuit, but I cannot find an exemption anywhere in the NEC
The 120 volts feeding the 24vdc power supply is already grounded.
See this paper from Mike Ode of ul labs it might help
http://www.ul.com/regulators/ode/0100.pdf
The 120 volts feeding the 24vdc power supply is already grounded.
See this paper from Mike Ode of ul labs it might help
http://www.ul.com/regulators/ode/0100.pdf
Although I couln't find any mention of an EGC in chapter 7, someone pointed out to me that 725.3 completely exempts class 1/2/3 circuits from having to comply with article 250; therefore circuits at 30V and lower do not require an EGC.
I think the article in the previous post's link comes to the same conclusion for almost the same reason.
I think the article in the previous post's link comes to the same conclusion for almost the same reason.
- Location
- Illinois
- Occupation
- retired electrician
I don't see anything in 725.3 that says Article 250 does not apply.
(edit)Nevermind...I see it now, but Class 1 systems can be 120 volts or more...why don't they require an EGC?
(edit)Nevermind...I see it now, but Class 1 systems can be 120 volts or more...why don't they require an EGC?
Last edited:
- Location
- Illinois
- Occupation
- retired electrician
Maybe I don't see it. The wording is not completely clear. It does not say that Article 725 systems are only required to comply with the listed sections, it just says you have to comply with the listed sections. However, it specifically says you are only required to comply with the sections of Article 300 that are referenced in Article 725. If both parts of 725.3 really mean the same, then why the different wording.
- Location
- Massachusetts
don_resqcapt19 said:
That was a question that kind of stumped me as well.
Your right. We aren't limited to 30V. See 725.41b. As long as the circuit is used for remote-control or signaling and does not exceed 600V, then it can be considered a Class 1 circuit. Since 725.3 doesn't specify that arcticle 250 applies, then Class 1 circuits do not have to comply with arcticle 250.
So the way I read this; the following circuits do not require an EGC:
120Vac start/stop motor controls
120Vac pressure switch signal
125Vdc switchgear close and trip controls
125Vdc door alarm signal
24Vdc level alarm signal
24Vdc analog (4-20ma) control
24Vdc analog (4-20ma) signal
Anyone disagree?
So the way I read this; the following circuits do not require an EGC:
120Vac start/stop motor controls
120Vac pressure switch signal
125Vdc switchgear close and trip controls
125Vdc door alarm signal
24Vdc level alarm signal
24Vdc analog (4-20ma) control
24Vdc analog (4-20ma) signal
Anyone disagree?
BTW; Chris Kennedy in the low voltage forum is the person that pointed out 725.3 to me.
http://forums.mikeholt.com/showthread.php?t=102842
http://forums.mikeholt.com/showthread.php?t=102842
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