I don't see how this would work. Wouldn't all the metal parts that aren't vital act as a ground of sorts?

Would the electricity not have to travel through the mechs internal components (A hit to the center of mass for example ) before reaching the ground?

Also about radiation

Source
Might be hard to control your mech when you are vomiting at the controls.

It really isn't gonna do jack ♥♥♥♥ immediately, they'll be able to fight for I'd say at least a good half an hour, even with a fatal dose. And behind several tons of armored metal, you'll need a hell of a lot of radiation. As for the taser, I doubt it'd be hard to rig up ground wires to the armor around the mech and direct it down to the feet and into the ground.

What about microwave weaponry/electrolasers?

Electrolaser is basically the taser idea.

Taser idea can still work if you catch em by surprise. I still think the radiation weapon is still in the ideas list, with the immediate incineration effect.

...sigh. No. You need to stop coming up with this pseudoscience-y stuff, man. Radiation can't kill you outright. It takes days, weeks, sometimes months to die from exposure to radiation or radiation poisoning. It's not like you can focus so much radiation into a weapon of some sort that it'll cause the enemy pilot's skin to slough off. Secondly, it wouldn't penetrate the mecha, by a longshot. Thirdly, how would you fire radiation? A uranium sprayer? Anything that you use in that sense will affect your mecha more than the enemy's. So, it's either "do nothing" or "kill yourself." Taser is kind of a good idea in theory, but I came up with a version that may be a little more effective below.

If you want to use something cool and science-y, here are some ideas:

• Flechette Cannon - Rip up a mecha by firing a giant load of heavy, razor sharp projectiles that can pierce and get stuck in hulls, potentially severing fuel lines and electrical connections. I imagine to implement this, it'd have to have some kind of delayed release for maximum range- like, say, CC's flak cannon. Otherwise, firing all of that at once is more like using CC's blunderbuss- very little range, very little effectiveness. This would probably have to have some kind of long reload to compensate for its high power.
• Electrolaser - The laser itself doesn't do much damage to the mecha; instead, it ionizes a plasma channel in the air which allows a massive jolt of electricity to travel for miles into a mecha, wreaking all sorts of havoc depending on where it hits. I don't think it would be capable of permanently disabling a mecha, but it might stun one for a bit, mess up some weaponry or sensors, etc. Basically, a support weapon.
• Micro-Rocket Launcher - A heavy weapon that fires hundreds of small explosive rockets. Great for area attacks, suppressive fire, or pummeling the hell out of a single mecha. Due to the fact that they're so small, these rockets aren't strong enough to penetrate heavy armor, so some mecha might be able to resist a full salvo without much effort.

I mentioned the electrolaser aswell, but it simply does not have enough power or stun duration for a 8 legged bot to get across the distance between firer and reciever, as I imagine 8 legged locomotion may prove slow.

The micro-rocket launcher may prove to be a issue with limited ammo, same as the flechette cannon.

Im trying to come up with something good and exotic, not something stupid and bizzare like a stun grappling net or something silly, but something that you are less likely to find on a mech.

EDIT : Heres a idea, Lightning gun. Combining the super heat and electric shock to inflict damage.

Fire folded up mecha spiders. Have them clog gun barrels and tear at armour.

Are you trying to troll? I honestly can't tell. How are you planning on harnessing the power of lightning? Are you only going to do battle during rainy days? Good and exotic is all dandy if you can come up with something that fits. Radiation gun? Silly. Taser? Fairly silly? Lightening gun? Straight up retarded.

Plus, a lightning gun would be more likely to hit you than it would an enemy. If you want a weapon that can deliver a large jolt of electricity accurately, then those are called Electrolasers, and have already been mentioned above.

Rolling.

HighEndNoob
Pierre Berguard [8]: You find your mecha where you would expect it, occupying the last slot in the Repair Bays, being held up while the robotic arms fix its leg joint so that it doesn't fall over. Again. It's coming along well, but it probably won't be ready until tomorrow. Ah well.
Abilities:
Inventory:
- Field Medical Kit
- Field Repair Kit
- 9mm Glock
Conditions:

Tomaster
Vladimír Shurla [4-1=3]: By shuffling your feet, you avoid stepping on a bullet again, and head out into the halls of the ship. Unfortunately, you're so absorbed in your shuffling that you don't notice where you're going, and 10 minutes later you look up and realize that you've no idea where you are.
Abilities:
Inventory:
- Field Medical Kit
- Field Repair Kit
- 9mm Glock
Conditions:
- Bruised Rear (-1 to walking, lasts 2 turns)

Mecha
Name: Goliath Mk.V
Class: Heavy
Weaponry:
- Two Heavy Cannons
-- Empty
- Hellfire FaF Missile Pod
-- Empty
Inventory:
Abilities:
- Heavily Armored (+1 to defense rolls, -1 to dodging attacks)
- Depleted Uranium Slugs (+1 to attacks using the main guns)
- Morale Boost (+1 to all allied rolls at the beginning of the battle, or when the Goliath arrives on the battle scene)
- Ypsilon Strike [SW]
Conditions:
Status:
Arms: OK
Legs: OK
Torso: OK
Etc: OK

Roast Veg
Aark-han [9]: "Mech needs an open station, I could do with some food and then a nap."
"Aye, well dere iddn't much I cahn do fer yer bot nao, seein as we're full oop erselfs. Food and shooteye tho', tha's easy. Lemme seh, where's a paper... Ah, heer, lemme draw ya a mahp."
The large man scribbles out a rough map of the ship, with three spots of interest. One is BOTS, another is FOOD, and the third is SLEEP... It's kinda atrocious. Well, the directions are clear enough, and you think you can find your way. You guess that's all that really matters.
Abilities:
Inventory:
- Field Medical Kit
- Field Repair Kit
- 9mm Glock
- Rough Map of the Exoneration
Conditions:

Mecha
Name: The Han Van
Class: Light
Weaponry:
- Innnardsplatter
-- Set to Long Range
-- 2/5 Rounds Loaded
---Reloading (-2 to firing next turn)
- "Le Big Tweezers"
- Some Kinda Acid Sprayer [SW]
Inventory:
- 15 AP Grenades
Abilities:
- Scream Siren
Conditions:
Status:
Arms: DANGER
-- Left Shoulder Damaged, armor at 23%, motor function at 50%
Legs: DANGER
-- Left Foot Damaged, armor at 0%, motor function at 0%, structural integrity compromised
Torso: OK
Etc: OK

Amazigh
"Amazigh" [9]: Satisfied with the night's lack of work, you flop down onto your bunk, put in earbuds to block out the sounds of the ship, and any possible idiocy that may occur in the room, and go back to sleep.
Abilities:
- Cyborg Enhancements
Inventory:
- Field Medical Kit
- Field Repair Kit
- 9mm Glock
Conditions:
- Asleep

JJA79
James Argus [6]: You walk up to a friendly looking mechanic lounging around.
"Hey, I was wondering, do you think you could train me in making mechanical things?"
She just stares at you with a funny look. Eventually, she realizes that there's no punchline.
"Oh wow, you're serious. Uh, it's really not as simple as 'learn to machine'. To work on mech like these, you need quite a lot of prior mechanical and electronic knowledge. If you don't know anything, then uh, well... I mean, I suppose that you could start reading up on basic electrical and mechanical engineering and ♥♥♥♥..."
"What? It's not THAT difficult, is it?"
She gives you a bemused smile.
"If it weren't THAT difficult, then you wouldn't need a college degree and 3 years of experience to do this for a living. Maybe fixing a car isn't too hard, but mecha are a hell of a lot more complex than cars.
Pilot
Abilities:
- Sniper expert (+1 when shooting from long range)
Inventory:
- Field Medical Kit
- Field Repair Kit
- 9mm Glock
Conditions:
- Panic (-1 to actions when in close combat)

Mecha
Name: Stinger
Class: Medium
Weaponry:
- Machine Gun
- Light Rail Sniper
Inventory:
- 8 LRS Slugs
- 550 .50 rounds
Abilities:
- Energy Blast [SW]
Conditions:
Status:
Arms: DANGER
-- Left Elbow Joint Damaged, Motor Function 0%
Legs: OK
Torso: OK
Etc: PROBLEM
-- Error in Primary Computer, Secondary Computer functioning

Tokochiro
John Kosloswa [10]: You don't know where such a silly thought about just asking for upgrades came from, but you dismiss it and head back to your room. You notice that your cigarette has burned down to a butt, so you discard it in the next trash you pass by. A few minutes of walking, and you've reached the room.
You head in and see Amazigh asleep on his bunk. You go over to JJ and your bunk, and start looking through your footlocker. Hmm... Aside from a few photographs you may or may not have gotten in a particularly lucrative game of strip poker, there's nothing interesting in here.
Abilities:
Inventory:
- Field Medical Kit
- Field Repair Kit
- 9mm Glock
- Cigarette
Conditions:

Game Events: 5 Rolls Left in the night. At the end of the night, everyone still awake will be forced back to their beds to go to sleep for a few hours before morning arrives.

By the way, if you want exposition, then just ask. You don't need to put it in an action or anything, just say "Hey HK, can you tell us how exactly the ship is laid out." or "Hey HK, how do we upgrade our mechs?". I'm benevolent, I enjoy writing up backstory/explanations, and I am okay with drawing up maps. Not necessarily competent at it, but I will for my players.

Alright, then.

• Why are we on a stolen ship? What faction are we fighting for? What factions are there?
• Can I get a rough map of the ship?
• What process is required to upgrade mechas? Will we have opportunities to periodically change out installed weaponry?
• What state is the world in?

"...sunnuvabitch!"
Go find Erroni and ask her if I can get the Heavy Cannon installed onto my Mecha.

Thats actually a good idea. I might use it. Seems exotic while fitting the spider mech design.

@Tomaster, the idea is feasible, but that link shows they are heading to production.

Persistence bordering stubbornness go!

>Ask where i may find these mechanical books then read them.

Just speed read it or something.