Metal Bed Frame - Exposed Conductive Part or Not

[Midwest]

So to try & keep confidentiality, a broad question without specifics;

A manufactured bed, mechanically operated by electrically powered motors. The metal bed frame would raise and lower the bed, and also be able to raise/lower the head of the bed and the foot of the bed. Would the metal bed frame fall into the definition of exposed conductive parts? The electrical wiring, to operate the actuators/motors would be attached to said bed frame.

If the bed frame would be defined as an exposed conductive parts, could it be a Class 2 piece of equipment?

 

[plugsandsparks]

I suppose its possible for it to be class 2. You can imagine how hard that would be to achieve with something as large as a bed with multiple components and wiring, especially motors. It could be ELV, which would make more sense for the remote parts and just have a single connection to a control box which is LV and DI.
Nearest i suppose i have connected is a motorised loft ladder and hatch, it was Class 1............

 

[littlespark]

Be 24v I reckon, with back up battery?? So it can be unplugged from mains and still operate.

Class II to a box/ transformer/ charging unit would be sensible.

What does MI say?

 

[Midwest]

To give a little more detail. Its something I look after, but not given a lot of thought to, until recently. Not sure, but I think the motors are ELV. The supply cable to the control box is the issue. We've started to find it being damaged regularly now, by user misuse.

Its just a standard twin flex, that can leave the metal frame, potentially in fault conditions, live. I suppose, if the motors are ELV, control box Class 2, then the supply box feed cable is just poor design? Not read MI instructions.

 

[Lucien Nunes]

I would be interested to know whether it is all ELV internally, much hunch is that it would be. Then the question would be on the relative risks associated with the frame becoming live if the supply flex is crushed against it, vs. indirect shock though being routinely in contact with an earthed frame. One would hope that they would configure the flex entry so as to make it very unlikely for it to contact the frame, even when the bed is moved. E.g. a transformer box clamped to the frame with the cable exiting through a strain-relief pointing downwards away from it. Not having seen it, I can't tell if there's some layout issue that puts the cable at greater risk. As a separate question, I wonder how often the occupant and/or caregiver actually come into contact with the frame, relative to other common electrical appliances?

 

[plugsandsparks]

Would be interesting to check out the MIs to see if there is any reference to RCD, say 10mA. Trying to account for physical damage to make safe under all possible scenarios would be an interesting thought project..

 

[Midwest]

The cables between control box and actuators/motors are quite short, and unlikely to get damaged. The supply cable/flex on the other hand is simply a cable 'tied' to the scissor part of the frame, the control box situated close behind the bed frame, and in the middle. Its where the cable leaves the apparatus, to connect to the nearby socket outlet, is where it is subject to rough service.

The occupant of the bed could touch the metal frame, and so could the caregiver. There are other electrical appliances, but these are typically Class 2, and no other touchable exposed or extraneous parts, close by. Although, the introduction of Class 1 products could be introduced.