AC Isolators

SRE · Jan 19, 2011

Could someone help me clear something up please? On the NICEIC training - don't groan, I know it was rubbish - we were told to use to ac isolators one either side of the generation meter but when I look at kits they always have just one isolator in them. So should it be one or two?????

High Tower · Jan 19, 2011

If your talking pv then it's a dc isolator pre inverter and a ac isolator post inverter

edexlab · Jan 20, 2011

( 1 DC isolator per string DC side)

1 Main AC isolator at origin of Ac circuit

DTI guide says;
If the ac switch disconnector and the inverter(s) are not in the same room
a local isolator should be installed adjacent to the inverter(s)
This is to facillitate maintenance of the ac cable run and inverter(s)

goodwilld · Jan 20, 2011

If you have system where the inverter is near the mains board and meters, you only need one. If the inverter is in the roof you need 1 x AC Isolator in the loft space and one at the mains board, this is a safety measure so no one can turn the power on by mistake, they have to be lockable too.
Hope this helps!!!!

jerriais · Jan 20, 2011

Thanks, I was wondering about this too.

GLES · Jan 20, 2011

The system I've just done has two AC Isolators. One just after the inverter, in the loft, and the second one by the consumer unit downstairs. Obviously there is a DC Isolator just before the Inverter too.

AC/PV · Jan 20, 2011

Has anyone found a suitable alternative to replace the rotary AC isolator by the consumer unit? I have no problems installing one in the loft, garage etc, but quite a few customers I've encountered find them a little to industrial looking when their consumer unit is situated in their hallway, living room kitchen for example and I can't say I blame them!
Any suggestions?

JulianC · Jan 20, 2011

I have fitted a couple of Santon units like this. Still not pretty but a bit better than most:

Quite expensive and a bit cramped inside to work with, so I'll use something bigger and cheaper if possible!

High Tower · Jan 20, 2011

Do they have to be rotary isolators??

edexlab · Jan 20, 2011

Rotary switches are used as they can only be locked off, in the off position, ie can't use DP main switch for this reason .Also i can't think of another option ,there's probably several but why look when rotary's are stocked everywhere and they're cheap.
On our MCS inspection he said we could use 20A DP switch next to inverter but main ac isolator must be DP and lockable as above ie rotary

AC/PV · Jan 24, 2011

Thanks for the opinions people and thanks JCDC, I've looked at that isolator and as you mentioned it doesn't give you much room to work in! I think the problem is that this required degree of protection is not normally found within the domestic sector and we are therefore forced to use what is available currently on the market, namely big bright isolators designed to be easily identifiable in a factory! Not something that is adequate and will look nice on mrs Jones's wall! The search continues...

Mark.W · Jan 24, 2011

I put AC isolator in the loft with inverter and DC isolator. The circuit can always be isolated at the board via the MCB.

Mark

Worcester · Mar 15, 2011

We have an installtion to do where the inverter will be in the loft space just above the utility box and the only sensible thing to do is to install henly blocks, a garage consumer unit, the total generation meter and an isolator in the utility box - see photo below.

My Sparks has said that

it will be tight to get all this equipment in here, but we won’t know for sure until we try.

Just have a back up plan in case it doesn’t all fit in. may not require an isolator as the mcb in the garage unit would act as that, you would need to buy an mcb locking device and padlock

Has anyone used lockable MCB's yet? Why wouldn't it comply?

edexlab · Mar 15, 2011

Before you go ahead with this idea you need to check with the DNO as I'm fairly sure you are'nt supposed to put any equipment other than switch fuses in there although I have seen consumer units in them worth checking though as they all have different policies
I have done this and got the ok to do so ,and managed to fit in an AC isolator /meter and 3 mod CU in similar space to the picture, he'll have to lower the meter to make it easier

As for lockable Mcb's they should'nt be used as they can be locked in the on position

JulianC · Mar 15, 2011

edexlab said:
As for lockable Mcb's they should'nt be used as they can be locked in the on position

Correct, and method of locking must be a standard padlock, not a special tool/key etc. See DTI guide pg.26

AC Isolators

SRE

High Tower

-

edexlab

-

goodwilld

jerriais

GLES

AC/PV

JulianC

High Tower

-

edexlab

-

AC/PV

Mark.W

-

Worcester

-

edexlab

-

JulianC

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