Reading HVAC schematic

j144441 · Oct 3, 2020

Just want to know what the spikes highlighted in red circles mean on the schematic attached?
Help would be much appreciated

Darkwood · Oct 3, 2020

I do my own schematics and I can honestly say I haven't seen that before nor can I find any such info, I thus can only assume it reflects on the DC negative as been grounded given it appears only on that line and it is strapped down to earth at the top of the schematic, it may be a custom designed addition to their own schematics for their own engineers to follow like a reference for testing purposes as these inhouse few day course engineers need all the help they can get from what I have experienced of them.
It may also mean it carries noise given it is strapped to earth and many electronics do dump their noise to ground.

I would be interested myself as to what it symbolises if any other members know.

Avo Mk8 · Oct 3, 2020

Sorry I don't have an authoritative answer, but my guess is it's to do with the physicality of the wiring. Is it that the conductor with the spike is a twisted pair with, or the shield of, the conductor touching the point of the spike. Each spike seems to be in a N or earthy wire and reaching over the 'hot' wire that pairs with it.
It's not the traditional/ IEC symbol for the above (as far as I'm aware), but might be the manufacturers simplified CAD version for clarity!

Can you see inside the unit if this hunch might explain it?

Otherwise I'm really interested to hear the answer!

Darkwood, you beat me to it - similar thinking!

snowhead · Oct 3, 2020

Looking at the the "Spike" it seems to indicate to me that the EE wire is looped around the 11v DC, although as above it may indicate the complete cable is screened.

Is this a real situation or an exercise drawing?
What environment is the HVAC unit in and what country was it made in?