Isolators

[Gavin A]

I thought I'd check the guidance in the 3rd edition of the guide to see if they were planning to clarify this situation. It seems the guide authors agree with my position on this

An a.c. switch or combination of switches must be provided for isolation and maintenance in the installation.


A switch for mechanical maintenance shall be provided in close proximity to the Inverter and shall fulfil the following conditions:
 switch all live and neutral conductors
 be securable in the OFF position only
 clearly show the ON and OFF positions and be labelled as ‘PV system – main a.c. isolator’


An accessible means of isolation shall be provided to isolate the a.c. circuit. MCB’s, RCD’s and main switches installed in accordance with BS7671 and in an accessible location can be used to fulfil the requirements for an accessible mea ns of isolation.

This is precisely the method we've been using, and while this new guidance is still only in draft form, I'll take it as sufficient evidence that our interpretation and application of the guidance is valid and safe.

 

[The Solar King]

Draft of DTI Guide third edition no longer mentions need for padlock.

[FONT=Helvetica, sans-serif]A.C. Switching Device[/FONT]


[FONT=Helvetica, sans-serif]Switching of the a.c. side of the installation shall comply with the requirements of BS7671,[/FONT]


[FONT=Helvetica, sans-serif]An a.c. switch or combination of switches must be provided for isolation and maintenance in the installation.[/FONT]


[FONT=Helvetica, sans-serif]A switch for mechanical maintenance shall be provided in close proximity to the Inverter and shall fulfil the following conditions: [/FONT]


[FONT=Helvetica, sans-serif]Switch all live and neutral conductors [/FONT]
[FONT=Helvetica, sans-serif]Be securable in the OFF position only[/FONT]
[FONT=Helvetica, sans-serif]Clearly show the ON and OFF positions and be labelled as 'PV system - main a.c. isolator'[/FONT]


[FONT=Helvetica, sans-serif]An accessible means of isolation shall be provided to isolate the a.c. circuit . MCBs, RCDs and main switches installed in accordance with BS7671 and in an accessible location can be used to fulfil the requirements for an accessible means of isolation. [/FONT]


[FONT=Helvetica, sans-serif]Note: At the point of installation of any a.c. switch-‐disconnector, the public supply should be considered the source and the PV installation the load.[/FONT]

 

[moggy1968]

you have to install to current regs (guidence if you like) not what is projected or in draft for the future. wether you think it makes sense or not thats the way it is.
I don't agree with paying tax, but I still have to!
I did say I wasn't absolutely sure of the situation with 2 isolators. It doesn't crop up with us as we would fit 2 rotary isolators if the inverter is away from the DB but I am more than happy to be wrong about this.

 

[Gavin A]

you have to install to current regs (guidence if you like)

do you actually appreciate that the 2 are different things?

not what is projected or in draft for the future.

As far as I'm concerned we have been complying anyway, it's just that our interpretation of the existing regulations and guidance obviously differs from yours.

In terms of working out who's interpretation is correct however, it's perfectly valid to point to the latest revised guidance even if it's in draft form to support the interpretation that matches the new guidance, as it clearly shows that the experts employed by the government to write the new guidance have taken the same view as us.

Bottom line on this stuff would be if a reasonable person would consider this to be safe and compliant with the regulations. I'm confident they would.

 

[moggy1968]

I do appreciate the difference thanks (did that on my business degree).
regrettably too much in this work is open to interpretation. Is it reasonable to ommit a £20 device in a £8000 installation, well, that depends I guess!!
I would certainly agree with the sentiments of your last post, especially the last paragraph. Most of this ultimately comes down to can you stand up in court and justify what you have done in the face of evidence from an 'expert' witness who will use the CURRENT regulations and guidence notes in their evidence. If you can, then happy days.

 

[mdovey]

I looked at this just before Christmas due to concerns over my own installation and concluded that the current regulations weren't clear, but that the new draft regulations clarified things.

As I recall (and this is a laymans view), the current regulations seem to be that if the inverter and CU are in different locations you need some form of isolator at both and that there should be a lockable isolator should "in an accessible location, e.g. the by the CU"

i.e. near the CU is an example of a suitable location for a lockable isolator but not the only option. It seemed therefore to depend whether a lockable isolator next to an inverter in say a loft was "an accessible location".

 

[Gavin A]

I'm confident I could if required, hence my comment in post 38 that you took exception to.

Anyway, I think we've covered this point now.

 

[SolarCity]

To be fair, I agree with Gavin's view on this.

In a related point, I have installed a couple of systems where the consumer unit was in the hallway of a home. To install a lockable AC isolator would have looked awful. I sourced a lock for the circuit breaker and decided that was fine. The isolator next to the inverter is lockable in the off position only.

You don't have to abide by regulations nor guidance anyway - you just need to be installing safely.

 

[moggy1968]

I'm confident I could if required, hence my comment in post 38 that you took exception to.

Anyway, I think we've covered this point now.

Don't worry Gavin, I don't take exception to an reasonable exchange of views:teeth_smile:
I've been proved wrong too often for that!

 

[BruceB]

You don't have to abide by regulations nor guidance anyway - you just need to be installing safely.

....... unless you are being assessed on it in which case abide by every whim of the rules and guidance.

 

[Gavin A]

....... unless you are being assessed on it in which case abide by every whim of the rules and guidance.

and don't forget to take photographs of everything at every stage just in case they need you to prove you've not used chewing gum to attach the brackets to the roof... and no they're not allowed to go up a ladder to check it themselves.

 

[duggy1979]

im now looking to use a modular generation meter which is approved) which can be installed within the garage unit so if you was going to work on the system for any reason then you would isolate the supply and lock off the rotary isolator adjacent to the inverter, so i think installing the system this way is a good arguement for not installing a lockable rotary isolator at the mains. Does anyone agree?

 

[The Solar King]

With you on this one. Am looking for well priced unit to take isolator, rcd, mcb & meter. Neat and hopefully cost effective.

 

[duggy1979]

ABB do a neat little meter which is MID approved, its twice the price of an elster but if space is an issue its ideal. Im trying to get my installs nice and neat myself, it will mount on the din-rail so could also be installed into various enclosures. once i have sourced my bits and pieces i will let you know

 

[Gavin A]

With you on this one. Am looking for well priced unit to take isolator, rcd, mcb & meter. Neat and hopefully cost effective.

we get ours from CEF. Haven't entirely worked out is it's cost effective or not, but it does the job. Inepro pro75D meter with an 8way box, RCD & MCB.

eta we buy them 10 at a time to get some discount on them. Really ought to check out exactly how much it all adds up to and how it compares to the alternatives.

 

[duggy1979]

we get ours from CEF. Haven't entirely worked out is it's cost effective or not, but it does the job. Inepro pro75D meter with an 8way box, RCD & MCB.

eta we buy them 10 at a time to get some discount on them. Really ought to check out exactly how much it all adds up to and how it compares to the alternatives.

thanks, i will have a look

 

[moggy1968]

wylex do a unit as well

 

[duggy1979]

wylex do a unit as well

thanks, i have just seen that one, im trying to keep it as compact as possible so just looking to see if i can source the bits and build my own unit