White wire on equipment ground bus UL 508

[xguard]

We had a control panel installed. It's UL 508 Listed by a control panel shop. I asked a question about a white wire being landed on the equipment grounding bus. It wasn't obvious to me what it was for initially. They said it's for a surge arrestor that was kind of hidden. There's also a black wire landed that should probably be taped green.

The arrestor is a LA 303 by Delta. I don't have the wiring diagram but found this on the website. (I should note this arrestor is not being used in service equipment.)




This is the response I received from the panel shop via the contractor “Yes, the white wire acts as a ground because if there is a surge, it shunts to ground relieving the surge. That does not violate NEC, as the panels are inspected for wiring codes before shipment.”

Am I crazy or is this wrong? It looks like they landed it on the grounding bus because there weren't enough spots on the neutral bus. Thoughts? Not trying to be nit picky with them just jumped out at me. Thanks.

 

[Elect117]

Some install instructions call out to put it on the neutral and others say EGC is okay when neutral is not present.

This might be a little nuanced though. Ask them for the SPD's listing code / manufactor and product code. Something so that you can find their install instructions. Or ask them for a copy.

 

[jap]

Well,,,, the instructions do say "connect to the grounded neutral buss", which it's not.

It's connected to the Equipment Grounding buss which must be kept separate from the Neutral Grounded Buss in the control cabinet since its fed from a Feeder.

Now if it's a Delta configured Surge arrestor and the white wire is actually acting as an EGC that's different.

Other than that it just doesn't look right.

Jap>

 

[TwistLock]

Those little external SPD's for HVAC equip etc. sometimes come with a green or white wire. (When Mars split with Intermatic they changed their knock offs to use a green wire). On the Intermatic's (etc.) I just slip on green shrink so I don't confuse any one. They mention this in their instructions. (bothers me too).

 

[jap]

If it's dual function, maybe make that conductor Green with White tracer or vice versa.

Jap>

 

[TwistLock]

Was curious to read article 285.27, that Intermatics instructions reference, and I see it was moved to Article 242 in the 2020.

“ 242.30 Connection Between Conductors. An SPD shall be permitted to be connected between any two conductors — ungrounded conductor(s), grounded conductor, equipment grounding conductor, or grounding electrode conductor. The grounded conductor and the equipment grounding conductor shall be interconnected only by the normal operation of the SPD during a surge “.