I have changed out a service panel from an old obsolete unit to a newer plug on neutral unit. I also installed a whole house surge protector. I did experience a problem in changing out the panel, the new panel was longer and the breaker locations, grounds and neutral connections further down in the panel than the previous panel so not all of the existing wires were long enough to easily wire up.

I had about 7 grounds that I had to wire nut to my extension wire in order to attach to the grounding bar. (Please don't think extension cord.. its bare copper wire to 10 inch bare copper wire.)

  • Question 1: Should I have scraped the paint under the grounding bar to make sure it was grounded to the panel or just let it be connected via the screws to the panel ? I had to route one set of wires really tightly in order to reach the breaker. I now have one light that the intensity changes when the Air Conditioning unit is running - it changes on a cycle about every 30 seconds or so you can notice the intensity changed and then changes back fairly quickly. I think this is the wire that was really short and I had routed across the main and the AC wires - probably not good but all I could think to do.

  • Question 2: I have this fluctuation in intensity - what should I be looking for to resolve the issue ? .. what can cause this? - my short wire I think is the one circuit - I am wondering if I should wire nut 6 inches of length so I don't have any crossing of wires but instead run parallel.

  • Question 3: In the original panel with 35 year old breakers there were two white wires connected to a breaker. The AC unit had two wires a white on the ganged breaker in slot 4 and a red wire (I think - it may have been black - I will need to double check), the water heater also had a white and a black wire connected to the ganged breaker. We all know white is supposed to be neutral. I am wondering why would any electrician do this ? Is there a valid reason why the Air Conditioning unit and the water heater would have white wires connected to the breaker and be hot wires ? (laziness , lack of wire ??) . I know the units are 230V units - so typically I should see a red wire a black wire, a white wire and a ground (or at least the 3 wires Red, Black and something) . Any ideas as to why and should I be looking deeper into this ?

  • Some 230/240 volt just need two hots plus ground(water heater, welders), so white wire is usually used, but should have black tape/paint on each end(marked hot). Short wires can be placed in junction boxes on side and extended into panel, instead of trying to make them fit.
    – crip659
    Jun 7 '21 at 16:37
  • 1
    You could have (or still could, if desired) connected an additional grounding bar to the panel higher up. My electrician put in 3, one each side and the top (which would be the bottom for most panels, as mine are bottom-fed, main on bottom) all jumpered to each other as well as being connected to the case. But extending the wires is also acceptable, if done properly.
    – Ecnerwal
    Jun 7 '21 at 19:53
  • @Ecnerwal so I can put the grounding bar underneath the incoming service feeds ?
    – Ken
    Jun 8 '21 at 14:52
  • More likely (and easily) off to one side or the other.
    – Ecnerwal
    Jun 8 '21 at 15:18
  • @Ecnerwal I have two of them ; one is off to one side and the other to the other side. The fact the panel has them so far down for the mounting screws is what makes it difficult. They did not put the mounting screws higher. However the fluctuating has stopped after I removed the G/AFCI combo breaker. I removed it and things seem to work.
    – Ken
    Jun 9 '21 at 18:00

As far as question # 3:

There are basically two types of wiring: cables and individual wires.

Generally speaking (there are exceptions at very large sizes), when using individual wires in conduit, the color coding (US/Canada) is:

  • White or Gray = Neutral
  • Green or uninsulated = Ground
  • Anything else - Black, Red, Yellow, Blue, etc. = Hot (including Switched Hot, 3-way Switch Travelers, etc.)

So if you have individual wires, neutral = White (rarely Gray) and non-neutral = non-White.

However, cables are always the same. 2-wire = Black/White. 3-wire = Black/Red/White. So when you are using a cable:

  • If you have a neutral, it must be the white wire.
  • If you do not have a neutral, you can use white as hot.

If white is used as a hot wire, it is supposed to be marked with another color on each end, but that is not always done (and/or not always noticeable, or taped and the tape falls off).

There are some situations (e.g., switch loops) where white is used as hot. But one really common usage is for 240V circuits. A 240V circuit that doesn't use neutral only needs 2 wires (plus ground), so black and white will both be hot. Water heaters and large resistance heaters commonly fall in this category. Dryers typically require neutral and, therefore Red/Black/White with white = neutral. Ovens, cooktops and air conditioners can be 240V (Black/White) or 240V/120V (Black/Red/White) depending on design.

The end result is that Black/White for water heater, and possibly air conditioner, is totally normal when using cables instead of individual wires.

  • 1
    I found no tape around the white wires (which were in jacketed cables), or in the bottom of the panel or any indication tape was used on the wires at any time no residue-mark. I thought Heaters have 120V & 24Vcontrol circuits and require neutral (I know you can get 120V Hot to Ground - but that is not safe/code), Personally 240V residential I think should always be fed with min 4 wires, A & B phase + Neutral and Ground, neutral required or not. I marked this as answer - good enough
    – Ken
    Jun 10 '21 at 13:01
  • As far as 120V and 24V for control circuits: 24V is typically generated via a transformer - and a transformer 240V -> 24V is fundamentally the same (just different ratio) as 120V -> 24V. As far as 120V for control circuits, there really is no need for that. Conventionally, particularly because of the prevalence of incandescent bulbs designed for 120V in the US, ovens have used 240V/120V with 120V for light, clock and (more recently, but decades now) controls. But those controls (and the clock) are now all digital devices running off low voltage DC so again 240V or 120V is a minor design Jul 1 '21 at 14:50
  • decision but not fundamental. Same for dryer light, motor and controls - all could be redesigned easily for 240V but inertia keeps them at 240V/120V combination. As far as "just run neutral everywhere": That is code now (but not for all that long) for light switches and similar. But for bigger stuff not as much of a need, and builders look at the bottom line. To you and me it is $25 extra one time (based on current pricing 10/2 vs 10/3 25' at Home Depot). To a builder it is $25 x 3 per house x 100 houses in a subdivision = $7,500 = a very nice vacation for the owner of the company. Jul 1 '21 at 14:53
  • Yes 24 VAC is from a transformer, just like the power to the house. Now with so many devices it makes sense to have the neutral, the power saver boxes and wall switches with WIFI etc need that neutral. Many years ago they wired switches hot only, we now wire with grounds, no one lost their vacation. That cost is passed on - the cost is relative. Yes I pay for it like 4 wires for my safe dryer/range. 240v Car charging, Generators, Solar Panel Inverters etc..
    – Ken
    Jul 6 '21 at 22:58

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