Control/Dimming Surge Protection for Dimmers

I'm currently working on an old EDI dimmer pack from the 80s and I started thinking. Whenever I hook something up in my shop or at a venue, it's protected from power surges. I have numerous levels of protection for my sensitive electronic equipment (computers, LEDs, practicals, even my DMX runs are isolated) though not for my dimmer packs. Should a surge blow out a few lamps or power cubes it is not THAT big of a problem. Should it fry my control cards, I'd be SOL. My dimmers are rather old EDI units that could be retrofitted with new controllers, but the cost to do so would be nauseating. It would likely be more worthwhile to just replace the whole pack.

My question here is:
I've found products ranging from $50-$500 that would do the trick. In your professional opinions, is it worth it? For such a sensible price it almost doesn't make sense not to.

I look forward to your input!

Regards,
Kent Zacherl

kentrzacherl said:

I'm currently working on an old EDI dimmer pack from the 80s and I started thinking. Whenever I hook something up in my shop or at a venue, it's protected from power surges. I have numerous levels of protection for my sensitive electronic equipment (computers, LEDs, practicals, even my DMX runs are isolated) though not for my dimmer packs. Should a surge blow out a few lamps or power cubes it is not THAT big of a problem. Should it fry my control cards, I'd be SOL. My dimmers are rather old EDI units that could be retrofitted with new controllers, but the cost to do so would be nauseating. It would likely be more worthwhile to just replace the whole pack.

My question here is:

"Should I put in-line surge protectors before the control board transformers? They are fused, but is that going to help if there is a surge? Would a panel mount surge protector be a better option because it would protect everything?"
​

I've found products ranging from $50-$500 that would do the trick. In your professional opinions, is it worth it? For such a sensible price it almost doesn't make sense not to.

I look forward to your input!

Regards,
Kent Zacherl

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Hello; Many / most economy surge protectors are simply sacrificial MOV's (metal oxide varistors) which clamp spikes a minimal number of times and give up their lives in the process. (sometimes spectacularly so when they blow up) If you want to educate yourself on serious surge protection, read up on a company named Surgex and the research of it's owners and partners. As with so many things in life, better products cost more money but 'buy once - cry once' comes into play here and you get what you're willing to pay for. Educate yourself BEFORE you part with your money.
Toodleoo!
Ron Hebbard.

The question is, what are you protecting if from?
Most dimmers will shrug off an over-current surge such as a blown lamp, and a MOV protector won't help on that anyway.
The other type of surge is an over-voltage surge. There are three principal causes for this, and the protection will vary:
1) Transient surge (HVAC motor starting, etc.) As long as these don't exceed the PIV rating of the dimmer's SSR/SCR, then no problem.
2) Lightning hit. Here, a panel style MOV will work, but may give it's life up.
3) Seriously crossed wires. (Think 13Kv line contacting your 120 feed) MOV will explode and dimmer will be blown anyway.
So, in other words, a lot of money spent to provide a narrow window of protection.
Now, the control board is a different subject. That I would plug into a combo surge suppressor / battery backup. The reason I would add that battery problem has to do with the corruption of data should a brief power interruption occur. (especially true if your board contains a hard drive.)

Surge protection is not fool-proof. Our building recently received a direct hit from lightning that blew a softball-sized chunk of concrete out of a pillar. It destroyed: our network switch, a couple HVAC network units, our fire alarm system, our school-wide intercom, and blew several 7517 chips on our architectural lighting control. I used to work for a business telco installer and we'd sell surge protectors and they failed all the time. But, this company had a warranty and would replace the protector as well as whatever equipment got hit. To me, that's a better guarantee and something I still look for in purchasing surge protection. Not sure about commercial grade protection, but I would guess there's something like that out there.

You need a surge protector that is designed to protect a main or sub panel. Install it at the panel that feeds the dimmer rack. The work needs to be done by a licensed electrician. Have a healthy fear of open panels and arc flash.

In SB's example, the cause of damage was probably current induced into long, low voltage cabling. If it had been on the power distribution, the damage would have been more widespread.

FMEng said:

In SB's example, the cause of damage was probably current induced into long, low voltage cabling. If it had been on the power distribution, the damage would have been more widespread.

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That's what we're thinking. Anything that grounded to conduit was messed with, particularly systems that run through underground conduit. We do have surge suppressors built in at both the lighting and main building transformers. They have 9 green lights that stay lit and when they stop staying lit we're to assume it needs attention.

The funny thing about lightning hits is they come with their own little EMP that can induce voltage in any nearby conductors, conduit, or even the building steal. The result is damage can show up in unrelated systems that were not actually spiked by the direct hit. Basically, anything that conducts becomes a receiving antenna for the magnetic pulse, then much like a secondary on a transformer, develops it's own voltage and (if connected to something completing the circuit) current flow.

JD said:

The funny thing about lightning hits is they come with their own little EMP that can induce voltage in any nearby conductors, conduit, or even the building steal. The result is damage can show up in unrelated systems that were not actually spiked by the direct hit. Basically, anything that conducts becomes a receiving antenna for the magnetic pulse, then much like a secondary on a transformer, develops it's own voltage and (if connected to something completing the circuit) current flow.

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Continuing your same train of thought; You get the same effect in metallic conduit when it runs for hundreds of feet racked up next to its neighbors on Unistrut. In a similar vein, this is another reason not to rack dimmer load circuits and unbalanced comms, balanced or unbalanced mic or line levels on the same unistrut racks. All the way along the run you end up with little conductive loops of metallic conduit with circulating currents between every cross-bracing conductive strut.
BTW; in the post I've just quoted, I noticed you spelled building steel as building steal. Cute! Let me know if you edit / correct your post. If you do, and if you let me know, I'll correct it in my quote and posterity will be none the wiser.
Toodleoo!
Ron Hebbard.

One thing to keep in mind is that the processor in a dimming rack doesn't just passively receive power from the line voltage inputs; it also monitors the zero-crossings in order to determine how to dim--and some even monitor the voltage in order to regulate the output. Anything that goes between the dimming processor and the power line (such as a battery backup mentioned earlier) has the potential to interfere with dimming performance. It would also likely require modifying the dimmer rack in a non-UL approved sort of way.

What you'd want is a Surge Protection Device that connects in parallel with the feed to the dimmer rack. As FMEng suggested, this is something that would require a licensed electrician to install. These devices are completely passive in normal operation and just step in to absorb spikes as they happen.