Nilfisk-Advance America GB 1133 - Manual (Page 11)

The works for configuring an extractor (connecting the cable, adjusting
the cutoff point) may only be carried out by a technician or skilled
personnel using suitable tools.
When using the vacuum cleaner outdoors, use only a type H07RN-F
cable.
Connecting the cable must be carried out according to the manual added
to the machine.
Even when the extractor is switched off, the interlock circuit might still
carry external voltage from the dust-producing system.
When the airflow control has cut off the dust-producing system, the main
switch has to be switched off as well in order to prevent an unintentional
start of the dust-producing system (after a malfunction has been
removed).
The recirculating airflow mustn’t exceed the 50 per cent of the incoming
airflow in order to comply with the required limiting values.
In case of variation (when high-quality separators are used or the
incoming air is very clean), the evidence of complying with the limiting
values has to be proved
.