electric shock from solar panels

[tony sayer]

FFS Den he's spent year and year up on roofs prodding and poking cables thru and around them and aerial mast's thru them etc etc...

There're not rocket science!..

[Vir Campestris]

Trouble is that when it's being cooked, spattered with carbon, and having jets of dirty water all over it it isn't going to work correctly. Can you guarantee it will never go wrong?

I might point out that never is a very very long time.

Andy

[harryagain]

That applies with any electrical equipment. But not work is almost the same as shut down. ie fail safe.

[Chris J Dixon]

Have a look at page 22 (14 of the .pdf), onwards in this document.

"Photovoltaics in Buildings Guide to the installation of PV systems 2nd Edition"

There is a decision chart which I am not going to reproduce, but the key details for average installs are

"...it is the electrical separation of the mains from the d.c. using an isolating transformer that is the key determining factor when assessing the requirement for array frame earthing."

"..freestanding ground mounted, or building roof mounted arrays (away from building metalwork) will normally not be within the equipotential zone."

"Where the incoming supply is PME (the majority of domestic supply arrangements), the PME earth cannot be taken outside the equipotential zone. This is to prevent the potential shock hazard should the supply neutral ever be lost."

" [if no isolating transformer] Install & bond to earth spike (Note: do not take PME out of equipotential Zone) (Note: Use 10 mm2 braid or equiv) "

further, on page 39 (22 of the .pdf)

"3.3.4 Shock hazard (safe working practices) It is important to note that, despite all the above precautions, an installer or service engineer may still encounter an electric shock hazard:

Always test for the presence of voltage of parts before touching any part of the system. Where a residual electric shock hazard is encountered, live working practices must be adopted (see above).

An electric shock may be experienced from a capacitive discharge ? a charge may build up in the PV system due to its distributed capacitance to ground. Such effects are more prevalent in certain types of modules and systems, namely amorphous (thin film) modules with metal frames or steel backing. In such circumstances, appropriate and safe live working practices must be adopted.

An example of where such hazards may be encountered is the case where an installer is seated on earthed metal roof wiring a large PV array. In such circumstances the installer must touch the PV cabling and can get an electric shock to earth. The electric shock voltage will increase with the number of series connected modules. The use of insulated tools and gloves, together with insulating matting to stand or sit on, can mitigate this hazard.

An electric shock may also be experienced due to the PV array developing a ground leakage path. Good wiring practice, double insulation and modules of Class II construction can significantly reduce this problem, but in any installed systems, leakage paths may still occur. Any person working on a PV system must be aware of this and take the necessary precautions."

Chris

[Vir Campestris]

No, it's not the same. In general electrical equipment with the mains disconnected isn't going to give you a shock. Sure there are mains filters but they aren'a major problem, and UPSes whic are, but are rare. But a burning inverter will _prbably_ fail safe. But it might stick all the DC from the panels out on the local mains circuit...

Andy

[Nightjar]

As I said, I would want to see the FMEA for the unit before making any such definite statement and the fire brigade won't have that to hand. They have to assume that it will not fail safe until proven otherwise. Meanwhile, they can't get to the seat of the fire and your house burns down.

Colin Bignell

[dennis]

So what if its wrong?

BTW I doubt if he is silly enough to poke wires and masts thru roofs. He is far more likely to fix a bracket or four to the wall.

[tony sayer]

I don't think thats a silly behaviour at all if done as it should be its fine sticking masts thru roofs as well...