Mattg4321

As above. You need an insulation resistance tester or you’re just guessing really. Then having to ‘bang test’ it. Clamping the earth is the wrong way to use an earth leakage clamp meter (assuming you have one designed for this and not just a standard clamp meter, where the resolution won’t be high enough at low currents to be useful). You need to clamp line and neutral together, mirroring what the RCD is testing.

That works if you have a low resistance fault. A lot, maybe even most, are not. It might be outside the scope of a low reading ohm meter/continuity meter and require an insulation resistance tester. No need to disconnect all the legs at this stage yet either.

That metal capping would barely stop a 5 year old with a sharp crayon. A drill or nail will go straight through it Needs to be steel conduit or 3mm plate or something in front of it.

The first thing to do with a fault like this is always always always insulation resistance testing. It solves 90% of these faults or more. If you haven’t got a tester or don’t know how to use it properly then your going to be flailing around in the dark… possibly literally!

Appleby boxes have always been my choice as they are generally the best. It’s is annoying though trying to use them when it’s double plasterboarded. Also, when using dry liners in general, if you fit them before plaster skim, make them a snug fit or they’ll move and pull a lump of plaster out at second fix. Why they set the locking tabs on the Appleby boxes at roughly 15mm thick, rather than 12.5mm (so they wouldn’t move) I will never know!! If you fit them after skim, then you will have a fairly ugly lip, visible with flat plate sockets etc. Also, if you want to remove one for access, and it’s fitted before the skim, it will make a mess to some extent or other. You also can’t fit them hard up against a stud as no room for the wing. Also, it’ll be an extra visit to the job if fitted before the skim as can’t be done at 1st fix. For all those reasons it’s knockout boxes for me! FYI if you want the Appleby boxes get them very soon. They are already disappearing from the wholesalers in my experience recently. I’ve moved over to the Click essentials ones. Can be used with double board and the lugs don’t flop around like some of the cheap stuff does.

This. Dry lining/plasterboard boxes are not as good as metal knockout boxes and nogs in my opinion. If one side is already boarded it can sometimes make it slightly trickier to wire, so prefer not.

I think you’re not fully understanding how it works. It’s a fairly complex subject though and it’s easy to get slightly confused about what exactly will happen in each scenario. It happens to me sometimes. I’m not entirely sure what you mean by earth loop and it being bad. I always associated earth loops with audio equipment and hum/noise. There is no mention of it in BS7671 as far as I can recall and I don’t see how this could be a safety issue. DNO Earth is the star point (neutral) at the transformer being tied to true Earth. Ie rod etc in the dirt. This will usually be done multiple times en route from transformer to your property - PME. If your property is a TT system - a minority of installations these days, but including caravans and building sites, then you have no DNO Earth connection on site. You whack a rod in the ground and your path to DNO Earth is through your rod and then through the dirt to the DNO Earth. You’re calling this a ground loop?? It’s a normal earthing system. If you’re in islanding mode, then the fault path will be back to the inverter and not back to DNO transformer. So the fact that you have tied your inverter neutral to earth via the neutral/earth bond relay and your own rod, means that is your fault path now. It doesn’t matter if you are still connected to DNO PME/TN-C-S system earth as this is no longer the fault path, as your power is derived from the inverter and not the DNO. You wouldn’t disconnect your bonding from the incoming gas and water supplies when in islanding mode would you. At this point, they are, electrically, just bits of metal in the ground, as is the DNO PME system. They are not part of the fault path.

You won't necessarily have an earth rod anyway as it's not mandatory. Not even for EV chargers now as most have built in PEN fault protection, meaning earth rods are not required as long as you meet other regulations. Neutral - earth bond is necessary for the proper operation of RCD protection. Stopping the voltage going back into the grid is a separate issue. Hybrid inverter can do as many circuits as the power of the inverter will be able to run. Nothing to say it can only operate a single circuit. I wouldn't take what Sunsynk say as gospel. They are certainly not experts when it comes to electrical installation - I've seen that Keith on their videos do some fairly dodgy things! Also, I seem to remember that some of their inverters will require NO and some NC relays!! FYI Sunsynk are rebranded Deye inverters.

The Sunsynk has an iirc 230v output that is triggered when the inverter is in islanding mode. This doesn't serve as the neutral-earth bond. You need to connect the output to the coil on a separate relay that will make the neutral-earth bond. An earth rod will also be needed if this is a grid connected system. Don't expect to find any explicit regulations in BS7671 as to how this should be done exactly, as they don't exist. Any circuits that you want to be able to use in islanding mode/off grid, need to be connected to the load terminals on the inverter. You really need someone who knows what they are doing to connect this up.

CEF can occasionally be good, but you have to negotiate everything. They are unbeatable on some items. Also, unlike TLC, they are a proper wholesaler and will get you anything. TLC are not really too interested if it’s not on their website. I’d never recommend a member of the general public goes to CEF though!

TLC are good if you have one locally. Quite competitive on most things and their pricing is very transparent- all on the website. I don’t get much of a discount even spending 5 figures there per year as their prices are already quite good. CEF on the other hand…

Should the steels be galvanised if outside the thermal envelope?? My SE insisted on it with a couple, but not sure if entirely necessary, but seemed like a sensible idea.

It’s the Vent Axia Sentinel FH. I’m starting to wish I’d gone for the Zehnder Comfoair though, which was also a contender. Size and cost swayed me towards the Vent Axia, which many on here seem to be happy with. Thanks for your help @Mike and everyone else. Looking at the figures, these comfowell manifold attenuators seem to perform significantly better than almost any pipework silencer than I can find, and it should be a relatively straightforward job to swap it out, so that’s what I’ll be doing asap when I’m back. Will update in due course.

Looked into this more thoroughly. I had thought you needed to be buy the manifold and also the attenuator, as well as both end plates (1x160 and 10x75). It appears I’d only need the attenuator and the end plates, which makes the cost slightly more palatable. Looking at the data and particularly at the low frequencies, what I find hard to get my head round is how 2x attenuators stacked, performs worse than only 1x at the low frequencies. Whats also slightly concerning is no 32Hz as part of their test. Would be frustrating to spend 300 odd quid and a few hours and not get a satisfactory result!

That Zehnder manifold looks like it costs over £500 with all the necessary parts!!!! Think I’ll look into a few more options first!