An employer must not use a ladder, or permit it to be used, if it -

- has rungs fastened to the stiles only by means of nails, screws, spikes or in like manner; or
- has rungs which have not been properly let into the stiles: Provided that in the case of welded ladders or ladders of which the rungs are bolted or riveted to the stiles, the rungs need not be let into the stiles; or
- has damaged stiles, or damaged or missing rungs.