The Electrical Certificate of Compliance explained

**ians** · 27-Jul-17, 09:38 AM

Originally Posted by dav

I have what is probably a dumb question, but what is the difference between an isolator and a disconnecting device?

the other way of looking at it...a circuit breaker for example can be used as a disconnecting device if it has isolating properties for example a geyser combo breaker.

andy i would be a bit cautious including a DOL starter...in some cases i have had been instructed that an emergency stop button connected to a DOL control circuit could not be used to isolate a circuit. I cant say for sure as it was an instruction i received from an electrical engineer...it would be an interesting topic to discuss.

**Justloadit** · 27-Jul-17, 01:51 PM

Originally Posted by ians

the other way of looking at it...a circuit breaker for example can be used as a disconnecting device if it has isolating properties for example a geyser combo breaker.

andy i would be a bit cautious including a DOL starter...in some cases i have had been instructed that an emergency stop button connected to a DOL control circuit could not be used to isolate a circuit. I cant say for sure as it was an instruction i received from an electrical engineer...it would be an interesting topic to discuss.

I suspect that the engineer stated this, as the disconnect, relies on a contactor to open its contacts.
If the contactor housing or coil bobbin is damaged/distorted for what ever reason, it may impede the release of the contacts arm and opening the contacts.
Also if the contacts have been welded due to a fault, then the release spring in the contactor may not have sufficient strength to physically break the electrical contact when the stop button is pressed.

**ians** · 27-Jul-17, 05:00 PM

Originally Posted by Justloadit

I suspect that the engineer stated this, as the disconnect, relies on a contactor to open its contacts.
If the contactor housing or coil bobbin is damaged/distorted for what ever reason, it may impede the release of the contacts arm and opening the contacts.
Also if the contacts have been welded due to a fault, then the release spring in the contactor may not have sufficient strength to physically break the electrical contact when the stop button is pressed.

that makes sense.

**Sparks** · 28-Jul-17, 08:29 AM

Depending on the application I also use a socket outlet as an isolating device which is acceptable.

**Sparks** · 26-Jul-17, 08:05 AM

Yes it may. Any new installation, alteration, extension or repair to an existing installation in some cases must be certified. Provided the rest of the installation is already covered by a valid COC.

**ians** · 27-Jul-17, 09:51 AM

Originally Posted by Sparks

Yes it may. Any new installation, alteration, extension or repair to an existing installation in some cases must be certified. Provided the rest of the installation is already covered by a valid COC.

If the COC was issued less than 2 years ago would you have to re inspect the installation to verify the COC is actually valid or just assume the installation is still reasonable safe and test the part of the installation you have done and attach the original COC

**AndyD** · 27-Jul-17, 08:51 PM

You're right Ian, DOL starter was a bad example, it may or may not qualify as an isolation device depending on its construction. The relevant standards for an isolation device are laid out in IEC 60947-3:2015, the SA standards authority adopted the IEC standard without any additions or alterations.

**Sparks** · 28-Jul-17, 08:26 AM

The chandelier is not a consideration unless there is a bowl over each lamp.

**Leecatt** · 17-Aug-17, 08:59 AM

Originally Posted by ians

If the COC was issued less than 2 years ago would you have to re inspect the installation to verify the COC is actually valid or just assume the installation is still reasonable safe and test the part of the installation you have done and attach the original COC

The only way to prove an existing Coc is valid is to inspect the installation, two years does not come into it.
Theoretically and correctly, one should issue an additional Coc only if the existing Coc has been proven to be valid.

**AndyD** · 15-Sep-17, 01:55 AM

The UK domestic electrical industry falls under Part P legislation, commercial/industrial is different so in a nutshell you'd need to at least partly requalify then join a scheme in order to certify work unless you do so at a higher cost through building control. Have a look on the ELECSA / NAPIT / STROMA / NICEIC websites for more in depth info. http://www.elecsa.co.uk/Contractors/Part-P.aspx