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Standby Generator Wiring

Question asked by garrys917 on Oct 7, 2019
Latest reply on Oct 26, 2019 by brianbaughman

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This is in reference to NFPA 110 Emergency and Standby Power Systems. 7.12.3 states:

If the conduit's point of attachment to the EPS in on the forcing function side of the EPS vibration isolation system, a flexible conduit section(s) shall be installed between the EPS unit(s) and any of the following so installed:

(1) The transfer switch)

That is all I'm interested in. Could anyone PLEASE translate "forcing function side" into English? LOL

We recently had a whole house 22KW Standby Generator put in and I would feel a whole lt better had they ran the sealtite from the generator all the to the transfer switch, which is located in the basement adjacent to the panelboard instead of cutting it off just after it entered the house. Just SE cable and a small control cable from there

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chiefns830 Oct 8, 2019 10:38 AM

Don't have time to research, but - you mention "whole house generator."

NEC is the standard that most AHJs adopt, and would cover a residential generator installation, not NFPA-110.

When you say SE cable, I'm hoping that it has four (4) conductors in the cable [SER]. This type cable can be used as exterior wiring.

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markselectric @ chiefns830 on Oct 22, 2019 11:33 AM

Garry,

I believe what they are referencing is, any flexible fittings attached to a genset are to be installed parallel to the engine crankshaft and rotor shaft. This is to allow for torque and vibration harmonics and or movement of the unit, as an example if a flexible fitting was run in a straight line to the unit, perpendicular to the crankshaft or rotor it puts excessive strain on the fittings.

In your case, it probably doesn't apply as most installs of a residential standby genset, it would or should be using a 90 degree fitting at the unit. If you look in the instruction/installation manual they show pictures as to how the flexible fittings are to arranged. This is really critical for fuel lines too, and I see it violated all the time on residential generators for the fuel line.

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markselectric Oct 22, 2019 11:41 AM

Changing over to cable inside a building is a very common practice, especially when using NMLT. Running NMLT inside a building in my opinion makes a lousy looking install, but that is JMO.

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chiefns830 Oct 22, 2019 4:42 PM

What is NMLT?

What is JMO?

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markselectric @ chiefns830 on Oct 22, 2019 6:49 PM

Non-Metallic Liquid-Tite

Just my Opinion.

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chiefns830 Oct 23, 2019 3:38 PM

Got it. I'm used to saying LFNC (Article 356), and IMHO. It threw me. Thanks.

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brianbaughman Oct 26, 2019 12:52 PM

First point, NFPA 110 does not apply to optional standby generators. NFPA 110 applies to Level 1 (NEC Art. 700) and Level 2 (NEC Art. 701) generators. Optional Standby is covered by Chapters 1-4 and Article 702 in the NEC.

Please read the Generac Installation Manual for your 22 kW generator. I am concerned over the type of "control cable" that was installed. The control circuits for that generator are Class 1 Remote-Control and Signaling Circuits, and REQUIRE a Chapter 3 wiring method to be installed.

I have lots of pictures with T-stat cable, speaker wire, Cat 5, and sprinkler control wiring being used for the control circuits. Type TC-ER-JP cable can be used, but that cable is a listed single cable assembly that contains the power and Class 1 control conductors.

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chiefns830 Oct 8, 2019 10:38 AM
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Don't have time to research, but - you mention "whole house generator."

NEC is the standard that most AHJs adopt, and would cover a residential generator installation, not NFPA-110.

When you say SE cable, I'm hoping that it has four (4) conductors in the cable [SER]. This type cable can be used as exterior wiring.
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- markselectric @ chiefns830 on Oct 22, 2019 11:33 AM
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  Garry,
  I believe what they are referencing is, any flexible fittings attached to a genset are to be installed parallel to the engine crankshaft and rotor shaft. This is to allow for torque and vibration harmonics and or movement of the unit, as an example if a flexible fitting was run in a straight line to the unit, perpendicular to the crankshaft or rotor it puts excessive strain on the fittings.
  In your case, it probably doesn't apply as most installs of a residential standby genset, it would or should be using a 90 degree fitting at the unit. If you look in the instruction/installation manual they show pictures as to how the flexible fittings are to arranged. This is really critical for fuel lines too, and I see it violated all the time on residential generators for the fuel line.
  Like • Show 0 Likes0
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markselectric Oct 22, 2019 11:41 AM
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Changing over to cable inside a building is a very common practice, especially when using NMLT. Running NMLT inside a building in my opinion makes a lousy looking install, but that is JMO.
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chiefns830 Oct 22, 2019 4:42 PM
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What is NMLT?
What is JMO?
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- markselectric @ chiefns830 on Oct 22, 2019 6:49 PM
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  Non-Metallic Liquid-Tite
  Just my Opinion.
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chiefns830 Oct 23, 2019 3:38 PM
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Got it. I'm used to saying LFNC (Article 356), and IMHO. It threw me. Thanks.
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brianbaughman Oct 26, 2019 12:52 PM
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First point, NFPA 110 does not apply to optional standby generators. NFPA 110 applies to Level 1 (NEC Art. 700) and Level 2 (NEC Art. 701) generators. Optional Standby is covered by Chapters 1-4 and Article 702 in the NEC.

Please read the Generac Installation Manual for your 22 kW generator. I am concerned over the type of "control cable" that was installed. The control circuits for that generator are Class 1 Remote-Control and Signaling Circuits, and REQUIRE a Chapter 3 wiring method to be installed.

I have lots of pictures with T-stat cable, speaker wire, Cat 5, and sprinkler control wiring being used for the control circuits. Type TC-ER-JP cable can be used, but that cable is a listed single cable assembly that contains the power and Class 1 control conductors.
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