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I read an interesting article about an invasive ant species the other day and was amazed by the following paragraph:

The ants can bite, but the biggest danger is that they're attracted to circuit boxes. The reason isn't known, but their sheer numbers can create an ant bridge between connections, shorting out entire electrical systems.

The journalist that wrote that probably doesn't know any more about electrical engineering than I do, so I thought I'd ask some of you guys... If this is good reporting, how does this happen?

Related questions:

  • How many ants do you think it would take to create a bridge between connections?

  • What would you do to protect your equipment from these ants?

  • Any theory into why they are so attracted to circuit boxes?

  • Or is this just bad reporting?

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    \$\begingroup\$ I don't think they are "attracted to circuit boxes" as such, it's just that circuit boxes typically have holes where cables enter and exit through walls etc which makes for easy access for the ants. \$\endgroup\$
    – Paul R
    Nov 30, 2011 at 13:54
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    \$\begingroup\$ Even if they did create a bridge, I would bet the resistance of their bodies would be high enough that it wouldn't cause any issues. \$\endgroup\$
    – Kellenjb
    Nov 30, 2011 at 13:56
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    \$\begingroup\$ @Kellenjb a human being can certainly create a short through their body (i.e. become electrocuted) by futzing around in a circuit box - I see no reason why a sufficient density of ants couldn't do the same. \$\endgroup\$
    – vicatcu
    Nov 30, 2011 at 16:13
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    \$\begingroup\$ @vicatcu like what Olin said in his answer "I expect their body impedance to be fairly high, seeing as they have exoskeletons and no sweat glands" \$\endgroup\$
    – Kellenjb
    Nov 30, 2011 at 16:16
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    \$\begingroup\$ @Majenko - I always assumed the moth was physically blocking the relay contacts rather than shorting them, but don't know for sure. The lab notebook page just says it was "in" the relay and one wing is damaged. en.wikipedia.org/wiki/File:H96566k.jpg \$\endgroup\$ Nov 30, 2011 at 17:26

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If the conductors are 1 ants length apart, then one ant is all it takes. If they are 10 ants lengths apart, then 10 ants, if they go top-to-tail.

In reality it will take more as they move around lots. Also, it is probable that it would be a gradual build-up of dead ants. As an ant gets electrocuted it will curl up and/or explode. After a while, the bits of dead ant will eventually bridge the circuit.

As for why... well, who knows what goes through the mind of an ant? (besides 110V)

It is well known and documented that mice chew through cables because of the 50/60Hz buzz they produce. Maybe the ants are attracted by the EMF exciting certain areas of their tiny minds?

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    \$\begingroup\$ +1... I had a LOL over "As for why... well, who knows what goes through the mind of an ant? (besides 110V)" \$\endgroup\$
    – Tevo D
    Nov 30, 2011 at 14:35
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    \$\begingroup\$ Circuits generally produces heat, ants like that temperature. Also it is a protected environment. \$\endgroup\$
    – Gunnish
    Apr 29, 2013 at 9:52
  • \$\begingroup\$ "It is well known and documented that mice chew through cables because of the 50/60Hz buzz they produce." Source? \$\endgroup\$
    – JAB
    Sep 14, 2016 at 18:07
  • \$\begingroup\$ @JAB I can't find it now, but I do remember reading a research paper once that proved mice were attracted more to a powered cable than an unpowered one or something. \$\endgroup\$
    – Majenko
    Sep 14, 2016 at 22:09
  • \$\begingroup\$ @Majenko Darn, I wanted to read more about it but couldn't find anything useful with a Google search. \$\endgroup\$
    – JAB
    Sep 14, 2016 at 22:10
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I had it happen to me :-) !!!
Really.
I may even have photos somewhere.

A junction box in my daughter's room blew a fuse / breaker.
From memory this was within about the last 5 years

Inspection showed that the box was largely filled behind the switch with a vast quantity of ant bodies and that major corrosion had occurred to the switch. I may have had to replace the junction box.

Crushed ants produce Formic Acid and presumably this plus a nice warm dry place + enough bodies is trouble. I don't know if they built a nest in the box proper (I suspect so) or used it as a graveyard.

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Ants are probably not much of a issue for low voltage circuits. I expect their body impedance to be fairly high, seeing as they have exoskeletons and no sweat glands. However at high enough voltage it could be a problem. I don't think a individual ant getting fried by 220V is much of a issue to the circuit itself. The current draw should be minimal, and the ant should burn up quicky enough.

There are two real dangers: First as Majenko said, dead ant bodies could build up eventually making a more permanent connection that could be a significant fire hazard. Second, a ant burning up could possibly catch something else on fire.

As to why ants are attracted to eletrical boxes, I don't know. I'm not sure they are in the first place. I certainly haven't seen any evidence of that in my house, but I don't store my sugar in the electrical boxes. Some animals can sense electric fields, although those are usually aquatic. For example, this has been shown in sharks and platypuses. I have no idea whether is true for ants. Again, I would check the original assumption that ants are attracted to electricity in the first place.

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  • \$\begingroup\$ I think I remember hearing that the hammerhead shark is particularly sensitive to electro-magnetic fields, as in orders of magnitude more sensitive than any instrument that has been created by man. \$\endgroup\$
    – vicatcu
    Nov 30, 2011 at 16:17
  • \$\begingroup\$ As mentioned in @Oli Glaser's answer, if the ants are wet or excreting liquid/laying eggs (all things they are prone to do), their impedence would be lower. \$\endgroup\$
    – mskfisher
    Nov 30, 2011 at 16:34
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    \$\begingroup\$ Humans can sense electric fields, too. At least the ones with hair can. \$\endgroup\$
    – endolith
    Dec 2, 2011 at 19:03
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How many ants would depend on various factors like:

Impedance of ant - not sure on this one as I have never managed to test one (it wouldn't stay still), but I would expect it to be normally pretty high (Megaohms) However it's possible if they were excreting some liquid, laying eggs, etc that it could be a lot lower.
I agree with the others that if many dead ants (>50?) build up between two points with a high voltage difference then at this point it may cause a possible fire hazard. This could be from the lowered impedance or even from them stopping heat being dissipated safely.

No idea why they might be attracted to the electricity specifically, I'd be wary of believing that without solid proof. It's possible they just like the convenience of a ready built and warm nest.

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They are, probably, other factors. Ants can be attracted by box temperature or other animals ants eat, that like boxes. Some animals use IR light or magnetic field to navigate. It is also possible, that boxes are installed at the places ants like to be or between those places and ants just "go through" it. Isolation is a quite tasty bit too.

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It's interesting that I happened upon this forum since I've been researching ant activity where electromotive force is concerned. It has been documented that ants are, for some reason, attracted to the energy that produces electromagnetic waves and because of that, they are often drawn to breaker boxes and power transformers. In fact, when large transformers are in operation, there are usually considerable numbers of colonies of ants that often invade the transformers. While ants have little water in their bodies, except for what they may be taking back to the colony, that gives them a certain amount of resistance to the flow of electrical current, thus making them impervious to electrocution. So you may wonder, if ants aren’t apt to be destroyed by electricity, what is the problem with them living in circuit breaker boxes and power transformers? The problem is this; when there are enough of them to substantially fill the container and the humidity is above 90%, they can act as a conductor and short out the circuitry. When conditions are just right, the short circuit can actually cause a transformer to explode. Because of that, an exploding transformer will blow the ants out of the container and when the cause of the explosion is investigated, there often is no sign of any ants. While circuit breaker boxes don’t explode, they do burn up, sometimes burning the house down, and thus destroy the evidence of what caused the damage.
Incidentally, sugar ants are the worst contributor to damage from fire since the ants may be carrying sugar and that, as you know, is an excellent source of carbon. It’s hard to believe that such small insects can cause so much damage, but now you know so be wary of ants… they can kill you.

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  • \$\begingroup\$ How about a reference to such documentation? \$\endgroup\$
    – DoxyLover
    Jul 12, 2014 at 4:49
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As answered earlier ants can contain formic acid , which is similar to the light acid in electric capacitors. If you could actually see a fractured ant it would probably also oxidize like an apple or lettuce. This oxidation could probably cause copper corrosion at the terminals which could cause a cold connection ( no current ) or a short. Capacitors can store electric energy, or reduce the amount of energy going through them. Ants in electrical components would be a bad thing. As to why they do this ? Because they can.

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