Inverter part of installation or not ?

[Derlyn]

So SANS 10142 covers any electrical installation between the Point of Supply and Point of consumption.

Definition of an installation is, and I quote

Machinery, in or on any premises, that is used for the transmission of electrical energy from a Point of Supply to a Point of Consumption.

COC's are issued for any work carried out on an installation.
For property sale purposes, a valid COC is needed and issued for the whole installation from the Point of Supply to all the Points of Outlet.


Now here is my query.

7.12.7.5

In addition it shall be recognised that the supply from each inverter, battery arrangement and PV panel ( or identified clustered group ), constitutes a Supply, and requires arrangements similar to point of supply, which shall include switch disconnection arrangements and shall comply with 7.12.5

From the above, it would seem that an inverter, together with panels and batteries, do not form part of an installation because, as in 7.12.7.5 above, they constitute a supply. The next question would be, why should they be included in a coc when they are not part of the installation ?

[GCE]

Hi Derlyn

The answer is within the question

COC is point of supply to consumption
Constitutes a Supply

7.12.7.5 is missing the Point of

Also look at the definitions for point of supply to determine if it is a Point of Supply or just a simple Supply

The definitions have changed and COC is from Point of Control to point of consumption - Basically the same just change in words to prevent clever people making the contractor sign a COC from Point of supply through transformers and multiply DB's when all you doing is a shoe shop in the middle of a shopping center with single phase 20 amp supply

[Derlyn]

Good morning GCE

I cocked up my post. Thanks for pointing that out.

I meant to say COC is from Point of Control to Points of Consumption.

Now if the inverter is referred to as a Supply as in 7.12.7.5, is that not before the Point of Control and therefore excluded as far as the COC is concerned ?

In your shoe shop example......... If the shoe shop had an inverter, it would be before the Point of Control of the shoe shop, therefore excluded from a COC that would be issued for the shoe shop.

Am I understanding this correctly, or is there something that I'm missing ?

[GCE]

No - The point of control is the point that can be switched off from point of supply which is a legal entity supplying electricity

Point of supply is supplied from Eskom , municipality or shopping center that becomes a supplier - if you supply yourself with electricity you are still a consumer and therefore it is after the point of control

Have a look at the definitions pasted below and let me know if we agree or if I am reading incorrectly



From SANS 10142-1 - ed3.2
3.56
point of control
point at which a consumer can, on or in any premises, switch off the electrical
installation from the electricity supplied from the point of supply

3.58
point of supply
point at which a supplier supplies electricity to any premises

3.77
supplier
in relation to a particular installation, any local authority (see 3.47), statutory
body or person who supplies, contracts or agrees to supply, electricity to that
electrical installation

3.16
consumer
person who is supplied (or who is to be supplied) with electricity by a supplier
(see 3.77); or a person who supplies his own electricity

[Derlyn]

Re your paragraph

"Point of Supply is supplied from Eskom, Municipality or Shopping Centre that becomes the supplier.
If you supply yourself with electricity you are still a consumer and therefore it is after the point of control"

I disagree.

What if the inverter was installed and owned by The Shopping Centre ? Would the shopping centre then become the consumer ? I think not.

I think that a consumer can also be a supplier. It's not the actual person or entity that's important but the point at which the inverter is connected, either before or after the point of control.

Who owns the inverter is irrelevant.

Added this last sentence in edit.

[GCE]

AT the beginning the shopping centre is the consumer and it is also the supplier further down the line

The shopping centre takes supply from Eskom - there is a point of supply by Eskom and a point of control , shopping centre main switch - The centre is a consumer ( definition 3.16) and it has common areas ( passage way lighting , toilets etc ) and it runs power to shops within/reticulates to a point in a shop ,called it Shop A , which has a tenant and is handed the responsibility under OHSA to be responsible for the electrical installation within the 4 walls it rents - The shopping centre " supplies" shop A with power and shop A has a point of control . Shop A is now the consumer has it has legally contracted to pay for electricity ( 3.16) and the center is now a supplier ( definition 3.77 above)

The section in the shopping centre that is common passages and reticulation to each individual shop ( point of consumption ) is part of shopping centre COC including any inverters/solar systems / alternative supplies that the centre may have. Once point of control is established in shop A that " falls" outside legal responsibility of the centre and becomes the tenants problem .
Think of a checkers/woolworths/pick and pay in a shopping centre who use there own contractors , engineers etc to design and install the electrical installation for there shop.

If we do a shopping centre the responsibility has to stop somewhere which is normally point of consumption , in this circumstance the main switch of the shop which is now point of control

[Derlyn]

Everything perfectly understood 100%.

2 further questions that might help me in understanding the inverter issue are;

1) What is the purpose of a Point of Control ?

2) What are the maximum number of Points of Control that an installation may have ?

[GCE]

Everything perfectly understood 100%.

2 further questions that might help me in understanding the inverter issue are;

1) What is the purpose of a Point of Control ?

To allow the tenant/occupier to isolate supply from the " Supplier" - If you referring to 7.12.7.5 , it states similar to point of supply

2) What are the maximum number of Points of Control that an installation may have

Basically 1 point of Control per Occupier/tenant - Shopping centre has one point of control associate with the point of supply , the point of control could be an MV point - The tenants have point of control to enable there area to be isolated

Generally in a domestic installation there will be one point of control as there is only one point of supply from Eskom - With an inverter/generator in the installation there will be alternate supplies within the installation but they are part of the consumers installation

[Derlyn]

If a house is supplied by an inverter only ( no municipal or eskom supply ) , would the inverter then still be included in the coc or will it be excluded being before the point of control ?

The same question can be asked about a house supplied by a generator only ( no municipal or eskom supply )

[GCE]

If a house is supplied by an inverter only ( no municipal or eskom supply ) , would the inverter then still be included in the coc or will it be excluded being before the point of control ?

The same question can be asked about a house supplied by a generator only ( no municipal or eskom supply )

When in doubt read definitions - I read that to have a point of control I need a point of supply which by definition means a contracted agreement with a utility

If it is the house owners inverter/alternative supply then it is just a supply and according to 7.12.7.5 needs to be treated similar to a point of supply with regards to isolation but it would form part of the electrical installation

I back that statement up with OHSA


OHSA EIR 2009
"electrical installation" means any machinery, in or on any premises, used for the transmission of electricity from a point of control to a point of consumption anywhere on the premises, including any article forming part of such an electrical installation irrespective of whether or not it is part of the electrical circuit, but excluding
(a)
any machinery of the supplier related to the supply of electricity on the premises;
(b)
any machinery which transmits electrical energy in communication, control circuits, television or radio circuits;

[Derlyn]

It's going to take me a while to wrap my head around this one.

Trying to put my mind in the same place as those who wrote the regulations.

Al I can say is one cannot really blame electricians for not interpreting the regulations correctly.

A point of control to turn off the power to an installation is sometimes a point of control, other times not, and when it's not, it is similar to one, but not one.

All somewhat confusing and I'll need a lot more time to try and understand it all.

[GCE]

An easy way is to think of it from an access point to isolate supply

If you receive power from Eskom you don't have access/ shouldn't have access to the sub station or kiosk as it is locked and so you need a point to be able to isolate ( control) so you can work on the installation safely

Like wise in shopping centers the tenant does not have access to the main D/Boards and so need that point to control the supply

If you have your own generator you have access to switch off and work safely .

From a responsibility point of view it is basically the same , or writing a COC for a tenant in a shopping centre - The sparky cannot be expected to start testing back in the sub station to get readings - He needs a point where he can start from and everybody knows where that point was that he tested at ( Point of Control)
In a installation with genset and no Eskom supply - you can start testing at the genset as you have access

[Thys LOW Elektries]

Also, look at the definition: "3.9 Certificate of Compliance Coc certificate that is issued by a registered person in respect of an electrical installation or part of an electrical installation". Here the definition doesn't mention from the point of control or point of consumption. So I guess if it transfers electricity or generates electricity and it is permanently connected to the installation it must be included in the CoC?
I see generators and inverters as a second and third supply to the electrical installation after Eskom. They must go through a point of control so that you can isolate them when needed and also too protect the installation if something goes BOEM!

[Thys LOW Elektries]

3.58 defines the point of supply and a supply is only a supply when it has a supplier per point of definition
Now if an inverter is connected to Eskom is the inverter a supply, since it is connected to a supplier, or a generator?

[Derlyn]

Is a supply but is not supplied by the supplier.