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I have an idea for a safety post but it would be a pointless exercise if 'sparkies' in the US could not learn from it. In the UK all electrical apparatus and electrical tools on a construction site must operate at 110V. They must also utilise a transformer using a center tapped secondary. (55 volts to earth). So the question is..... what are the safety parameters for construction site electrical items in the US? The question applies to earthed ( grounded ) tools and equipment and also all insulated tools and equipment. Respectively called - class 1 and class 2.


Frank
 

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Town Drunk
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The one requirement at the top of the list is GFCI protection for all 15 and 20 amp 120v receptacles. If it plugs in, and especially if it is on an extension cord, use Ground Fault Circuit Interrupter (GFCI)
 

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OSHA is very strict with this subjct.
They also look for grounding pins intact on plugs and damaged cords.
 

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On a large construction site, "spider boxes" are normally rented. They are most often installed, maintained, and moved around by the electrical contractor as part of his contract. They have a 50 amp input, normally, and a feed through receptacle to go to the next spider box in the next work area or on the floor above. They have a series of regular, gfci protected receptacles for the tradesmen working near that spider box to plug their tools into. Many contractors require their men to use a little GFCI pigtail at the head of all their company owned extension cords, regardless whether they believe they're plugging into a GFCI protected circuit or not. Better double safe, than not at all is the theory, I guess.

Spider box:


GFCI pigtail:

 

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DGFVT
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View attachment 113

Use factory-assembled cord sets.
Use only extension cords that are 3-wire type.
Use only extension cords that are marked with a designation code for hard or extra-hard usage.
Use only cords, connection devices, and fittings that are equipped with strain relief.
Remove cords from receptacles by pulling on the plugs, not the cords.
Continually audit cords on-site. Any cords found not to be marked for hard or extra-hard use, or which have been modified, must be taken out of service immediately.
A flexible cord may be damaged by door or window edges, by staples and fastenings, by abrasion from adjacent materials, or simply by aging. If the electrical conductors become exposed, there is a danger of shocks, burns, or fire.
The OSHA construction standard requires flexible cords to be rated for hard or extra-hard usage. These ratings are derived from the National Electrical Code, and are required to be indelibly marked approximately every foot along the length of the cord. Examples of these codes are: S, ST, SO, and STO for hard service, and SJ, SJO, SJT, and SJTO for junior hard service
Extension cords must be 3-wire type so they may be grounded, and to permit grounding of any tools or equipment connected to them.
When a cord connector is wet, electric current can leak to the equipment grounding conductor, and to humans who pick up that connector if they provide a path to ground. Such leakage can occur not just on the face of the connector, but at any wetted portion. Limit exposure of connectors and tools to excessive moisture by using watertight or sealable connectors.
To reduce hazards, flexible cords must connect to devices and to fittings in ways that prevent tension at joints and terminal screws. Flexible cords are finely stranded for flexibility, so straining a cord can cause the strands of one conductor to loosen from under terminal screws and touch another conductor.
 
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