We have an older church building that we would like to put our parking lot lights on a timer. We purchased digital timers only to find out that there is not a neutral wire within the switch boxes. We would like to run a neutral wire from the breaker box to the switches, does the neutral wire have to continue out to the lights? The switches only have 2 wires into and out of them, no ground.

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    Can you post photos of the insides of the switch boxes in question please? Nov 7, 2020 at 20:30
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    That's really unusual unless the light switches are out in the parking lot. Where are the switches? Are you sure you're telling us about every single wire in the box, including ones that do not go to the switch? Getting us photos as ThreePhaseEel advises would be VERY helpful, edit your answer to include them. If you take your pix from a different device than you posted the question from, then register your account to an email/password or Google/Facebook ID so you can log back in from any device. Nov 7, 2020 at 21:55
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    Without knowing the scale of the parking lot lighting, I wonder if the switches are controlling relays that control the light circuits. Other than that, seems like a normal switch loop setup, rather than "really unusual" - but rather than running from "power at the overhead light" to the switch location, running from a junction box on the way from the electric panel to the parking lot, branching the switch loop off to the switch location.
    – Ecnerwal
    Nov 7, 2020 at 22:32

3 Answers 3


A church is a commercial facility so use caution on advice received on this site most are not familiar with the unique requirements to commercial construction. Could you provide a photo of the wires entering the box? Also how many lights and the type?

there may be a contactor controlling multiple runs I use 3 phase contactors to control 3ea 20 amp strings on 120/240v services.

there are timers that need no neutral check out an intermatic STO1 they run in the mid 30$ range and the timer is battery powered so no neutral is needed and power bumps don’t affect it. The battery last about 2 years.

The nice thing about this timer is it is astrometric or you can turn on a feature to turn on at sunset and off at sun rise it updates itself based on your location. I use them at my plant to turn the yard lights on at 3am then off at sunset, on again at sun set then off at 1030 pm or the time they shut down for that day then they don’t turn on for a day that we never work would be great for a church where scheduled services and weekly Bible studies or choir practices. If you need it on when it’s not programmed tap it and it will stay on until tapped again or the next scheduled off time. I drive small (15 & 20 amp circuits) with this timer and if the loads are larger drive contactors (power relays).

Depending on the area and construction type you may have conduit that’s why I asked for a photo and a neutral could be pulled in conduit in commercial facilities. buildings with occupancy requirements are normally wired with conduit.


Retrofitting a cable with a neutral wire may be far more expensive than a different solution that does not require rewiring the building - unless by chance you have conduit for the wiring? If you do have conduit, it's a simple retrofit and you'd only need to get the neutral to the switch location - the lights already connect to neutral somewhere else. The neutral to the switch location would need to be the same neutral that the lights are using. That neutral should be present where the switch loop branches off from the light circuit. And it has to be a whole new cable with neutral if it is a cable rather than conduit setup.

NEW installations are required to provide neutrals (and grounds) at switch locations.

Different options would include putting the timers in a different location in the circuit where neutral is already available. While not as convenient as having the switches and timers at the same location, you might not need to use the switches so much (or at all?) with the timers in play.

  • Wiring in a commercial facility usually requires conduit. Thinking NMB ? It’s only appropriate for residential 1-2 family (class 3,4,5 ).
    – Ed Beal
    Nov 7, 2020 at 23:53
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    Kinda depends how old the wiring in the church is; I'm hopeful that it's conduit because it is an occupancy that should be (and it makes the fix easy), but most of the churches I know were electrified a LONG time in the past, as they were around for a good while before electricity came out. How much they got updated after that tends to be limited, as there's always something else (like the roof) that needs funds.
    – Ecnerwal
    Nov 8, 2020 at 0:06

You can't run a neutral from the panel to the switch; code requires that the conductors of the circuit all must run together. So if you're going to run a neutral, you'll want to run it from the light to the switch.

Some electronic switches, like timers, operate without a neutral, using the safety ground for the return current for the electronic controls. If there's a safety ground present, that's probably the easiest solution. Note that this only works if the device is specifically designed to operate that way - it's not OK to substitute the safety ground where the instructions tell you to use a neutral.

So if there's a green ground wire present, that's probably the easiest solution. If the wiring is run in conduit, the conduit can serve as the safety ground; but if there's conduit, you could just run a neutral wire to the light in the conduit.

It is probably possible to install the timer (or a photocell) in a location upstream from the lights. The switch could still be used to override the timer to turn the lights off.

There are also smart switches / wireless automation products that would allow you to install the control in that upstream location and program the lights for a schedule.

Note that a church is what the National Electrical Code considers an "Assembly Occupancy" and there are a few special rules that apply - see NEC article 518. In particular, it adds restrictions on the wiring methods permitted. Depending on the fire rating requirements of the building, NM cable (Romex) might not be permitted.

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    Wiring in a commercial facility usually requires conduit. Thinking NMB ? It’s only appropriate for residential 1-2 family (class 3,4,5 ).
    – Ed Beal
    Nov 7, 2020 at 23:51
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    @Ed Beal - A lot of churches around here are old, not always GEC, BX cable, a lot are wiremold - some were gas lit when built and had electric lights added later (later being 1920's haha) But you see a little bit of everything in churches, volunteer work, etc. Nov 8, 2020 at 0:01

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