Splicing GEC (NEC 250.64(C)(1))

[solarengr]

Is there a limit to how many splices or taps can be made on one GEC?

Here's what I'm trying to do:

I design solar systems using micro-inverters (every solar panel has its own inverter). A big pain (and high cost) part of this is that each inverter needs to be grounded. This ground not only serves as an equipment ground (EGC) but also as a grounding electrode conductor (GEC) since one of the DC leads from the solar panel is bonded to the metal enclosure of the inverter. What I'd like to do is pre-install a bare copper #6 GEC to the microinverter so that when my subcontractors are on-site, all they need to do is use either a barrel-shaped splice or C-Tap with a compression tool (from Panduit, Thomas and Betts, or whoever) and splice the GEC from two adjacent micro-inverters.

There are 21-24 micro-inverters per circuit so there would be 21-24 splices/connectors per circuit.

Is this code-compliant? Does anyone see a problem with this?

From my understanding of 250.64(C)(1), this is acceptable as no limit is set.

Thanks in advance for any suggestions.

 

[Dennis Alwon]

The main GEC must be continuous but you can split off as often as you like with either a irreversible splice or split bolt without cutting it.

 

[drive1968]

Enphase specifies in its installation instructions to either use a continuous grounding conductor or a grounding washer. If you want to save time, the grounding washer is the way to go. But it seems from the manufacturer instruction that splicing some wire for each microinverter is not allowed.

http://www.enphaseenergy.com/downloads/Enphase_M190_M210_User_Manual.pdf

 

[drive1968]

By the way, which model of Enphase are you using where you are able to get that many microinverters on each circuit? The model I use only allows 13 per 15 amp circuit.

 

[solarengr]

By the way, which model of Enphase are you using where you are able to get that many microinverters on each circuit? The model I use only allows 13 per 15 amp circuit.

I use the M190-208 V.

 

[solarengr]

The main GEC must be continuous but you can split off as often as you like with either a irreversible splice or split bolt without cutting it.

The NEC says (250.64(C)) "GEC's shall be installed in one continuous length without a splice or joint except as permitted in (1) and (2)
(1) Splicing shall be permitted only by irreversible compression-type connectors listed as grounding and bonding equipment or by the exothermic welding process.

The way I read that is that if you have two separate lengths of GEC copper wire, you can use an irreversible compression-type connector to splice the two and, per the section quoted above, this would still be considered one continuous length of GEC.

If someone thinks I am misinterpreting the code, please let me know.

 

[raider1]

The NEC says (250.64(C)) "GEC's shall be installed in one continuous length without a splice or joint except as permitted in (1) and (2)
(1) Splicing shall be permitted only by irreversible compression-type connectors listed as grounding and bonding equipment or by the exothermic welding process.

The way I read that is that if you have two separate lengths of GEC copper wire, you can use an irreversible compression-type connector to splice the two and, per the section quoted above, this would still be considered one continuous length of GEC.

If someone thinks I am misinterpreting the code, please let me know.

I would agree with your interpretation.

Chris

 

[Dennis Alwon]

I thought I said that in a convulted way. Irreversible crimps are allowed- I did say that, continuous length with split bolts off the continuous piece is alowed. This may help a bit

 

[al hildenbrand]

The NEC says (250.64(C)) "GEC's shall be installed in one continuous length without a splice or joint except as permitted in (1) and (2)
(1) Splicing shall be permitted only by irreversible compression-type connectors listed as grounding and bonding equipment. . .

My experience has been with the Burndy HyPress and connectors, but the tool is, to me, very expensive, and really bulky, for the smaller GECs that are my common install.

I'm interested in knowing of lighter tools and connectors, in the #8 to #4 guage range, that meet the standard called for in 250.64(C). Any one got ideas?

 

[solarengr]

Everyone, thanks for your help.

 

[eprice]

The NEC says (250.64(C)) "GEC's shall be installed in one continuous length without a splice or joint except as permitted in (1) and (2)
(1) Splicing shall be permitted only by irreversible compression-type connectors listed as grounding and bonding equipment or by the exothermic welding process.

The way I read that is that if you have two separate lengths of GEC copper wire, you can use an irreversible compression-type connector to splice the two and, per the section quoted above, this would still be considered one continuous length of GEC.

If someone thinks I am misinterpreting the code, please let me know.

I kinda think I disagree, though I'm still thinking out loud here. 250.64 (C) (1) allows splicing of the GEC, but it doesn't allow tapping. What you have described doing is not splicing. It is tapping. The only section within 250.64 that allows tapping is (D). That section doesn't really cover what you are doing, but I would be comfortable with allowing it as an alternate means. (D) requires that the taps be made in such a manner that the common GEC remains without splice or joint.

 

[infinity]

The GEC ends at the tap. The other conductors are bonding jumpers. Here's a graphic from the NECH, not sure if it complies with the OP:

 

[solarengr]

I kinda think I disagree, though I'm still thinking out loud here. 250.64 (C) (1) allows splicing of the GEC, but it doesn't allow tapping. What you have described doing is not splicing. It is tapping. The only section within 250.64 that allows tapping is (D). That section doesn't really cover what you are doing, but I would be comfortable with allowing it as an alternate means. (D) requires that the taps be made in such a manner that the common GEC remains without splice or joint.

Here's how I define splicing and tapping:

Splicing is when you take two pieces of wire and join them into one (i.e. they both terminate in the connector). In the end, you have one ground path. I would consider this a series connection.

Tapping is when you have one conductor pass through a connector and another terminate in the connector and branch off in a different direction. In the end, you have 2 separate paths. I would consider this a parallel connection.

250.64(D) is there to make sure you size that tapped conductor correctly.

 

[tommyrice]

grounding micro-inverters

grounding micro-inverters

I think you could use split bolts because you are tapping off main GEC.My question would be what criteria would you use to size main GEC?

 

[Dennis Alwon]

I think you could use split bolts because you are tapping off main GEC.My question would be what criteria would you use to size main GEC?

The main GEC is sized per T250.66 based on the size of the service entrance conductors. Look at the notes.