Technical information

1.7.4 Internal Wiring

Approved conductors of Low-Voltage Limited Energy circuits should be separated

or isolated from conductors of the other circuits unless they are insulated f or the

maxim

um v oltag e present.

It should be noted that (as for Class 2 circuits) if internal non approved

conductors are used for example N07V-K or H05V-K, what has been said above is

no longer applicable and it is necessary to separate or isolate these conductors.

1.7.5 Circuits and components excluded from class 2 and

Low-voltage limited-energy circuits

Attention to the product:

–Safety devices like immaterial safety barriers, safety limit switches, sensitive

edges etc.

–motors & power loads, inverters, 24v step motors, etc.

Even if inserted and connected to power sources in class 2 and/or Low-

voltage limited Energy sources they should always be approved by an

NRTL laboratory.

1.8 Transformer and self transformer protection

NEC, CEC and UL508A do not really make distinctions between transformers and

self transformer,limiting themselves to preventing the use of the self transformer

in some civil systems.There is no limitation placed on its use for adapting the

input voltage to the electrical equipment panel.

Transformer protection follows in precise rules in the NEC and the CEC

egardless of whether the use is power or control, while the UL508A makes a few

distinctions.

The NEC and CEC are how e v er diff erent: the difference cannot be neglected

because it is often the cause of non conformities in Canada, where stricter rules

are applied.

CONTROL CIRCUITS