Good afternoon everyone. I have a Tesla gen 3 wall charger which requires installation on a single-phase domestic property with a PME (TNCS) supply. The charger has built-in ground fault detection (GFCI), but some sources suggest that a separate PEN fault detection device is also required for the installation. Any thoughts?
Ginnaflys
Hi, you need to contact a qualified EVSE installer to fit it on the correct size RCBO with DC and PEN protection. unless say it is already in the EVSE
From Tesla's Gen 3 wall connector's installation instructions:
Additional requirements apply to UK properties fed from a TN-C-S supply. In most scenarios, these
properties will require an external device which provides PEN fault detection and isolation in accordance
with BS 7671. It is the responsibility of the installer to ensure that the requirements of BS7671 are met -
please refer to Tesla's application note at the end of this manual that discusses this topic in more detail.
So, no, Tesla's kit doesn't do PEN fault detection itself, there would have to be another solution to address the rare cases when the supplier's TN-C-S earth fails. An external box like a Matt-E would work, as should a dedicated local earth rod (but for some reason, Tesla don't think it would, presumably because a local earth rod might not be as easy to install and get a good earth as the installer would hope it to be.)
Any qualified EVSE installer electrician will be able to advise what would suit your installation.
Additional requirements apply to UK properties fed from a TN-C-S supply. In most scenarios, these
properties will require an external device which provides PEN fault detection and isolation in accordance
with BS 7671. It is the responsibility of the installer to ensure that the requirements of BS7671 are met -
please refer to Tesla's application note at the end of this manual that discusses this topic in more detail.
So, no, Tesla's kit doesn't do PEN fault detection itself, there would have to be another solution to address the rare cases when the supplier's TN-C-S earth fails. An external box like a Matt-E would work, as should a dedicated local earth rod (but for some reason, Tesla don't think it would, presumably because a local earth rod might not be as easy to install and get a good earth as the installer would hope it to be.)
Any qualified EVSE installer electrician will be able to advise what would suit your installation.
You missed this bit on the Manual:
Ground Monitor Interrupter: The ground monitor interrupter allows the installer to select different early monitor options. Wall Connector continuously checks for the presence of a safe earth connection and automatically recovers from faults. Earth assurance operates by injecting a small amount of current into the earth conductor in order to measure the impedance between line and earth. If high impedance is detected, the Wall Connector will lock out charging and display a error code of two (2) red blinks. See Error Codes on page 40 for a full list of error codes. For earth assurance to operate on TN grids, one leg of the distribution transformer must be earth-bonded (Neutral). Earth bond should only occur at one location in a site's electrical system. Wall Connector earth assurance may be adjusted in countries with TT or IT grid configurations and can be disabled in the commissioning procedure. The Earth Monitor Interrupter feature monitors the Wall Connector earth connection. Select the correct option based on the installation's earthing system and earth impedance. Depending on country, three options are available: • Enable: Earth connection will be monitored and a high detected earth resistance will disable the Wall Connector. This is the preferred setting to provide protection, and should be selected where earth connection is expected to be strong (as in the case on TN networks and most TT networks), and where required by regulation. • Disabled: Earth connection will not be monitored. This should be selected where the earth connection is not made (as is the case for IT networks), or where the current induced by this check would be problematic (as is the case on some TT networks with sensitive residual-current devices). Temporary problems such as earth faults or utility power surges are resolved automatically.
In essence you select 'Ground Monititoring' Enable when installing on a TN system (USA calls it Earthing a 'Ground')
Ground Monitor Interrupter: The ground monitor interrupter allows the installer to select different early monitor options. Wall Connector continuously checks for the presence of a safe earth connection and automatically recovers from faults. Earth assurance operates by injecting a small amount of current into the earth conductor in order to measure the impedance between line and earth. If high impedance is detected, the Wall Connector will lock out charging and display a error code of two (2) red blinks. See Error Codes on page 40 for a full list of error codes. For earth assurance to operate on TN grids, one leg of the distribution transformer must be earth-bonded (Neutral). Earth bond should only occur at one location in a site's electrical system. Wall Connector earth assurance may be adjusted in countries with TT or IT grid configurations and can be disabled in the commissioning procedure. The Earth Monitor Interrupter feature monitors the Wall Connector earth connection. Select the correct option based on the installation's earthing system and earth impedance. Depending on country, three options are available: • Enable: Earth connection will be monitored and a high detected earth resistance will disable the Wall Connector. This is the preferred setting to provide protection, and should be selected where earth connection is expected to be strong (as in the case on TN networks and most TT networks), and where required by regulation. • Disabled: Earth connection will not be monitored. This should be selected where the earth connection is not made (as is the case for IT networks), or where the current induced by this check would be problematic (as is the case on some TT networks with sensitive residual-current devices). Temporary problems such as earth faults or utility power surges are resolved automatically.
In essence you select 'Ground Monititoring' Enable when installing on a TN system (USA calls it Earthing a 'Ground')
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