[RE-wrenches] Splices in service panel

Tue Sep 13 10:44:20 PDT 2016

Hi Ray,

I get your take on this. Certainly reviewing what manufacturers are
recommending helps. Generac has a pre-wired transfer switch backup panel,
but it is hard to tell from the literature what they are recommending we do
with neutrals:

http://www.generac.com/all-products/transfer-switches/home-backup

It seems clear to me that 300.3(B) requires all conductors of the same
circuit to be routed together if run in metallic raceway. Perhaps the
exception in 300.3(B)(3) Nonferrous Wiring Methods would allow neutrals to
stay back if you run your conductors in nonmetallic raceway or sheathing.
NEC 210.4 Multiwire Branch Circuits stipulates more requirements relating
to grouping conductors.

Best,

August

*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *Ray Walters
*Sent:* Saturday, September 10, 2016 12:46 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Splices in service panel

Hi August;

I'm glad you brought this up.  When I first saw only the hots being brought
to the Critical Load Panel, I thought it was wrong too, but then I recalled
that this is similar to a switch leg.  Does 300.3 forbid switch legs too?
the exception in 404.2(A)  allows switch legs, but does it apply here?  I
don't have a definitive answer in regard to 300.3, other than to note it
has numerous exceptions.  300.3(B)(4) may also apply, and further, over
current device enclosures and J boxes are not specifically mentioned
either.

To be clear, I am not the originator of this idea;  I just copied this
method from Reliance and Generac's wiring of their UL listed circuit
transfer switches.  I have used it since 2003, and never had an AHJ have an
objection.  I've discussed it with AHJs and electricians that specialize in
generators, and this is common when retrofitting a backup generator.

Also in response to the person that posted about having trouble with the
neutrals: we have no neutrals at all in the CLP, if done this way.  All
neutrals land on the main neutral buss in the main panel.  The CLP only has
hots to the breakers, and the "neutral" bar in the CLP is used only as the
equipment ground for the enclosure by adding the green bonding screw.

To be clear, I would not use this method on new construction where the
branch circuits could be brought straight to the CLP.  This is for *retrofit
only*.  I also would not do this if the CLP and main panel were connected
with a nipple longer than 24".  Further, I over size the nipple and use PVC
to reduce any possible inductive heating issues. For very short nipples, I
have to use RMC, but I would never use EMT.

This method helps keep the space requirements down to comply with 312.8(2),
and keeps the wiring cleaner, fewer splices, and less over all disturbance
to existing wiring in the sometimes aging and crowded main load center.
The trade off is possible inductive heating of a short nipple caused only
by lower current 120 vac circuits (the 240 vac hots cancel each other's
inductance).

 Again, I'm not the AHJ, and I'm not the originator of this method.  I'm
just doing my best to describe a method used in the backup generator world
that I've found helpful.
The NEC and our work essentially is a compromise of numerous competing
safety concerns.  The code describes many wiring methods; its up to us to
optimize each situation for overall safety.

Here's a screen shot from the Reliance manual:

R.Ray Walters

CTO, Solarray, Inc

Nabcep Certified PV Installer,

Licensed Master Electrician

Solar Design Engineer

303 505-8760

On 9/9/2016 12:45 PM, August Goers wrote:

Ray,

I’m intrigued by this. We’ve always gone off NEC 300.3(B):

(B) Conductors of the Same Circuit. All conductors of

the same circuit and, where used, the grounded conductor

and all equipment grounding conductors and bonding conductors

shall be contained within the same raceway, auxiliary

gutter, cable tray, cablebus assembly, trench, cable, or

cord, unless otherwise permitted in accordance with

300.3(B)(1) through (B)(4).

I interpret this to mean that we need to run neutrals along with any branch
circuits we are moving over.

Best,

August

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On
Behalf Of Ray Walters

Sent: Thursday, September 08, 2016 5:44 PM

To: RE-wrenches

Subject: Re: [RE-wrenches] Splices in service panel

Hi Chris;

Its the same as a switch leg for a light.  The neutral stays at the light,
only the hot is run down to the switch and back.

Also, with some critical load panel set ups available (ie Generac), there
is no provision to even run the neutrals to the new CLP.

This is cleaner and involves much less splicing.  Fewer connections is
usually better in my book.

R.Ray Walters

CTO, Solarray, Inc

Nabcep Certified PV Installer,

Licensed Master Electrician

Solar Design Engineer

303 505-8760

On 9/8/2016 6:22 PM, Chris Mason wrote:

I disagree with the response that you do not need to move the neutrals. You
should never have the load's phase wiring in one panel and the neutral in
another.

Chris Mason

NABCEP Certified Solar PV Installer™

Solar Design Engineer

Generac Generators Industrial technician

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