Most homeowners on discovering rats in the ceiling would generally distribute Ratsak 100g Fast Action Throw Packs 5 x 20g Packs and call it a job done. You could go the more humane route and set a The Big Cheese Rat Cage Trap and relocate the pests elsewhere.
If you were looking to enlist a professional I would suggest someone from a pest control service. Although they won't be able to give you a specific assurance on questions like whether the rats have made wiring unsafe by chewing it, they should be able to let you know if they believe you'll need an electrician. Whilst the pest controller is there they can seal up any entrance holes and remove the rats from the ceiling. - MitchellMc
Baits are great but if you do have any animals that are likely to eat the dead mice then this is not desirable. One or two won't hurt them but if there are large numbers regularly - then I think a trap is better. You can get humane ones now. You should also seal the gaps in the shed where you can but you will struggle to seal them all and they will only go elsewhere looking for food. - robchin
The only thing that worked for us was to get in professionals who set up pet-friendly traps for us. They were gone almost immediately. - KingStreetReno
Make sure to remove any potential food sources for the rodents and make sure your property is generally clean and tidy. If food source is easier somewhere else they'll move. Also, if you're that type of person, invest in a cat. It's amazing how much of a deterrent just having a cat in the house is. Pets also come with other benefits. Be careful with baits and traps. Make sure you remove any captured rodents or you'll end up bringing in bigger pests like possums. - Dale
I was told that if the rodents have already set up a nest at your place then the noise of an electric repeller is unlikely to drive them away. However, if they haven't yet established themselves and are just looking for food the noise might be enough to drive them away.
With traps, you need to always wear gloves. Rats in particular are smart and if they can smell us on the trap they are unlikely to go near it. - Kermit
I read about someone who had great success at repelling mice by threading cotton balls onto a wire and dripping some peppermint oil onto the cotton balls. They placed the unit where mice were getting in. In my case mice were getting in through the doggie door, so I placed the cotton balls there at the bottom of the door. I have not seen a mouse in the house since! I was amazed that such a simple device could repel mice! - Prof
We started with basic rat traps, putting them almost everywhere, including the house roof as they had started to migrate. I also removed all sources of food by putting the chicken, duck and dog food in metal barrels instead of plastic. I then did a bombing round of poison in the roof of the house as the dogs tend to wander the shed and I didn't want them eating the pellets. That worked really well as we haven't had any in the roof since.
Our issue then lay with insulation in our shed. They had tunnelled in it so the only reason they were staying was for the nice home. At the moment we are getting rid of the insulation and we are planning to replace it. My issue now is how to stop them from getting back in. I've done a lot of research and some people swear by steel wool, while others swear by different caulking. - MonkeyLearn
It won’t stop them getting in but we poison them outside. We use lengths of stormwater pipe, cap it at both ends, then drill a hole in the middle of the caps big enough for rats. Baits go inside. - JDE
We are constantly battling mice in the yard (thankfully not inside) and because we have 2 dogs as well as free roaming chickens, we put square baits in sealed containers or a capped poly pipe with a hole just big enough for them to squeeze in. Works a treat! - rattle
Careful if your mice get into the bait station then die outside the bait station where a free roaming chook might wander. Just as a friendly heads up my chooks absolutely love eating mice they find (dead or alive, they catch their own as well). - Prawns