Wiring in Displays

Many folks, even within our industry, look at various lighting technologies and find vast differences. However, in many respects these light sources, per our codes, demand the exact same treatment regarding their wiring methods. Last month, in this column we commenced tracing out our general branch circuit for any type of sign. We had put a lot of emphasis on the system’s ground and how grounded/grounding/bonding, besides being code, could prolong the lifespan and trouble-free operation of all our light systems, especially neon and Light Emitting Diodes (LEDs). Therefore, holding consistent to that train of thought, this month we’ll pick up with the conductors just prior to the sign circuit’s disconnect and trace the route just past that first element in our sign and outline lighting system.


A disconnect is located in a sign’s branch circuit either upon an exterior return/cabinet/raceway or, for remote installs, behind a wall normally within six feet of the first remote transformer, power supply or in the case of a remote LED installation, enclosed driver.

The disconnect principle is used throughout both Canadian and American codes in everything from HVAC (heating, ventilating and air conditioning systems) to hot water heaters and water pumps and includes many other forms of electrical equipment. Signs, electrical displays and outline lighting are all really forms of equipment and therefore the disconnect principle must be closely adhered to. In “remote” sign circuits it seems that many believe a snap switch on the side of a transformer box or a self-contained unit will conform to the code, but that’s not the case.

Unfortunately, I can remember being at a trade show in Atlantic City and listening to one transformer manufacture’s representative telling an attendee that the reason their self-contained transformers had a snap switch on the case was to comply with the code’s disconnect issue.


A remote sign system’s disconnect is an actual standalone box that in most cases contains a lever, which can be pulled up or down and aligns two metal rings through which an actual padlock can be placed—thus the term lockable disconnect. To fit the criteria of the code, this disconnect also has to be able to place the circuit in the open position when locked.

Anyway, since we are still on the supply side of our sign circuit, making sure that the hot, neutral and grounding conductors are sorted out and clean (being shared by no other branch) is of major importance. Plus, just to make sure that we’re all on the same track, remember to check the amperage of, and the sizes for, the incoming branch conductors that will be running our displays. If the conductor sizes are #10s or smaller, we probably will be ringing out a 30-amp circuit, which is the not-to-exceed size for neon. If the conductors are sized for #12s, we’d be looking at an incandescent, fluorescent or LED, etc, type of load. Remember those technologies call for a circuit that does not exceed 20 amps.

This electrical box with a lever on it (the disconnect) is where many of you will pick up the installation process of a sign. In a remote install (where you have letters or outline lighting on one side of a wall and the trannies, drivers, ballast or power supplies on the other or back side), this is in all probability, where your installation work will commence.

Is a disconnect important?

I would say so. It’s the law of the land and its usage can keep you from getting kicked off a ladder by an energized circuit even in the short run. On the other hand I can remember how at one Vermont mall (quite a few years ago) because a remote channel letter sign possessed a disconnect, when its trannie had overheated from improper air circulation and was creating heavy smoke from within the suspended ceiling, it only took one fireman with a ladder a short period of time to de-energize, turn off the entire circuit and thus circumventing the permanent destruction of any signage.

Now, here comes a sad scenario. In all the years that we’ve/I’ve been installing signs and believe me, that’s been a whole bunch, I can only remember a few occasions where a lockable disconnect has been present on a sign installation, even though this has been the law of the land for decades. Now, maybe as a company you may not feel this is necessary because you’re mainly involved with installing remote LED characters.

That’s wrong again!

The same law that governs all signage is in place here and all grounding, disconnects, and wiring must be executed in accordance with the rules set forth in our North American code books (National Electrical Codeand Canadian Electrical Code).

OK so let’s set up a disconnect. The most prudent thing to do is to stock these items on your installation truck(s). What we normally do is stock one 30-amp and one 20-amp pull lever type model. Also, to save money we don’t stock the fusible types because any over current is normally handled at the service panel in a way that is code compliant.

Following another scenario, if you don’t feel confident about putting in the first couple disconnects, make arrangements right when you first get the job to have the on-site electrical contractor handle that part of the install for you or your client. You can go to the site and tell the general contractor what you want and need and where you want it placed. That way you won’t find yourself in the situation that we all have at one time or another—having the disconnect on one side of the transformer’s placement while having the location where you really want all your conductors to tie in, on the other side. The most logical and preferred placements for any disconnect, in a crawl space, is someplace along a line that you would have to pass in order to get to your transformers. That way anyone else servicing or called by security to disable the sign would have to pass and be able to disarm the display before getting to its power supplies. Remember, one of the reasons among many is that the codes (written by the National Fire Protection Association and in Canada, the Canadian Standards Association) are drafted by safety organizations for the protection of life and property.

After the disconnect is installed, which is usually within six feet of where the first transformer, ballast, power supply, or driver box are going to be installed, the normal procedure is to attach the whip. Standard practices usually dictate a six-foot whip be left for any of the following electricians for that is what has always been allowable for grounding/bonding purposes when the conduit alone is utilized as that conductor. Even though, with all of our sign systems, a dedicated grounding conductor is requested by all our power supply manufacturers, and common sense practices within our trade, let’s stay with the six-foot industry standard, which makes the project a lot more professional.

Also, notice I mentioned a whip (metallic in nature) as opposed to EMT or other form of rigid raceway. While EMT (pipe) is what we would probably use if we were installing the disconnect and had the first box set, this is probably not what to call for if you are planning to include this required control for the first time or are having the on-site electrical contractor make it up for you. The big thing with using a whip (Flexible Metal Conduit) is that you have a wide range of adjustments you can use, whereas with pipe, those adjustments are severely limited.

Also, if you are making up this whip for the first time always install 1/2˝ stock. This is called for in the trade and if you have more than one circuit you won’t have to worry about fill capacities. Note: fill capacities are the number of conductors in which size and amount are factored in.

As always, double check all your connectors to assure that they are really tight and that all the paint had been scraped away from where the connector’s shoulder and lock washer will be resting.

Not being new to our industry, I’ve seen many unfortunate instances that could have been avoided by installers just following the Code and administering industry standards regarding this disconnect practice. For example, about two years ago, a friend of mine had serviced a sign and had to leave that sign incomplete while he went for some additional supplies. He had taped off all the controls and had told the owner of the facility not to energize the sign because it still needed additional work. Unfortunately, there was no lockable disconnect and the client, wanting to attract some attention, disregarded the “Do not operate!” warning he had been given and decided to energize his display anyway. That restaurant later had a fire and there was quite a bit of damage.

How uneventful this whole matter would have been if the installation would have been to code, for all my friend would have had to do was to throw the disconnect lever into the open position and slap a lock and tag on it.