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Posted By Topic: mcb as isolator for outlet

Dec 26 2017 20:42

Hi I am looking to put socket outlets on the side of a generator for ease of use.
was thinking of putting a weatherproof switchboard on the side with 56 series socket outlets and a couple of cee form outlets.

My Question is do the cee form outlets need to have isolators or can the MCB for the circuit act as the isolator or should i put a 56 series isolator for the cee form outlets that don't have isolators?

Thanks in advance.

Dec 26 2017 20:56

also the switchboard will be next to outlets.

Dec 26 2017 21:16

You have not provided sufficent information to give a answer,

Q1 What else is the generating set supplying at the same time aa something plugged into the proposed socket outlets?

Q2 Is the generating set connected to a electrical installation by a detactable connection?

Q3 Is the generating set connected to a electrical installation by a indtalation wiring?

These question all need to be answered to detrimine how the generating set is required to be earthed.

AS/NZS 3010:2017 does NOT currently have an answer to the question you asked, it is to be included in an upcoming amendment.

Dec 26 2017 21:28

Thanks for your reply.

Q1. Generator will only be supply loads pluged into outlets.

Q2 & 3. The generator will not be connected to an electrical installation.

Generator will mostly be used on construction sites as temp mains I have been told.

I will be putting in RCDs and an MEN link on the generator as per the customers request to have RCD protection.


Dec 27 2017 07:01

AS/NZS 3010 issued May 2017 in appendix B has rhew necessary information look for "RCD protected generator set". The information for both single phase and three phase is provided.

As for the distance between the socket oulet and the isolating switch, use as/nzs 3000 clause, but noting it is going to be used on a construction and demolition site, this would indicate that the IP rating needs to be at least IP 34 for the control switch and the socket outlet.

Dec 27 2017 12:07

Pluto's answer covers matters you didn't ask about, but fails to provide the information you wanted.
The answer to control of genset-mounted sockets is in 3010: 2017:

B2.4.2 Socket outlet control switching
The circuit breaker provided for generating set overcurrent protection may be used for the control for a maximum of two adjacent socket outlets.
If three or more socket outlets are provided on the generating set, or, are contained in a switchboard fixed or adjacent to the generating set, the following requirements apply:
(a) All socket outlets should be individually controlled by an adjacent control switch.
(b) All switches or overcurrent devices should operate in all live poles (including the neutral conductor).
(c) The rating of the overcurrent device should not exceed the rating of the smallest rating socket outlet.
(d) The designated earthing terminals of all socket outlets should be connected to the equipotential bonding conductor and the generating set frame to AS/NZS 3000 requirements for a separated (isolated) supply or RCD protected supply.
(e) For an attached switchboard only, the total loading of the input to switchboard should be limited by a switchboard mounted circuit breaker; the maximum current rating should be the lesser of the plug rating or the current rating of the connecting cord to the supply source.

Dec 27 2017 17:39

Thanks for the info guys.
Appreciate it